From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id 3BD4413832E for ; Wed, 27 Jul 2016 23:52:16 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id DB515E0979; Wed, 27 Jul 2016 23:52:12 +0000 (UTC) Received: from smtp.gentoo.org (smtp.gentoo.org [140.211.166.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id A8E23E0979 for ; Wed, 27 Jul 2016 23:52:11 +0000 (UTC) Received: from oystercatcher.gentoo.org (unknown [IPv6:2a01:4f8:202:4333:225:90ff:fed9:fc84]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.gentoo.org (Postfix) with ESMTPS id BE711340D06 for ; Wed, 27 Jul 2016 23:52:09 +0000 (UTC) Received: from localhost.localdomain (localhost [127.0.0.1]) by oystercatcher.gentoo.org (Postfix) with ESMTP id D910A78D for ; Wed, 27 Jul 2016 23:52:06 +0000 (UTC) From: "Mike Pagano" To: gentoo-commits@lists.gentoo.org Content-Transfer-Encoding: 8bit Content-type: text/plain; charset=UTF-8 Reply-To: gentoo-dev@lists.gentoo.org, "Mike Pagano" Message-ID: <1469663516.c8839f5a116f5e0d27d587a09b40e1cc668c9885.mpagano@gentoo> Subject: [gentoo-commits] proj/linux-patches:4.6 commit in: / X-VCS-Repository: proj/linux-patches X-VCS-Files: 0000_README 5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.6.patch 5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.6.patch1 5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.6.patch 5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch2 X-VCS-Directories: / X-VCS-Committer: mpagano X-VCS-Committer-Name: Mike Pagano X-VCS-Revision: c8839f5a116f5e0d27d587a09b40e1cc668c9885 X-VCS-Branch: 4.6 Date: Wed, 27 Jul 2016 23:52:06 +0000 (UTC) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-commits@lists.gentoo.org X-Archives-Salt: 3fbd8370-6f01-46d1-9b2f-aef76c48049f X-Archives-Hash: 2998ef02e3434a15035c6106a418cd02 commit: c8839f5a116f5e0d27d587a09b40e1cc668c9885 Author: Mike Pagano gentoo org> AuthorDate: Wed Jul 27 23:51:56 2016 +0000 Commit: Mike Pagano gentoo org> CommitDate: Wed Jul 27 23:51:56 2016 +0000 URL: https://gitweb.gentoo.org/proj/linux-patches.git/commit/?id=c8839f5a Add BFQ patches for 4.6.X: http://algogroup.unimore.it/people/paolo/disk_sched/patches/4.6.0-v8/ 0000_README | 16 + ...oups-kconfig-build-bits-for-BFQ-v7r11-4.6.patch | 103 + ...ntroduce-the-BFQ-v7r11-I-O-sched-for-4.6.patch1 | 7097 ++++++++++++++++++++ ...arly-Queue-Merge-EQM-to-BFQ-v7r11-for-4.6.patch | 1101 +++ ...rn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch2 | 6361 ++++++++++++++++++ 5 files changed, 14678 insertions(+) diff --git a/0000_README b/0000_README index 67da565..9e42d11 100644 --- a/0000_README +++ b/0000_README @@ -91,6 +91,22 @@ Patch: 5000_enable-additional-cpu-optimizations-for-gcc.patch From: https://github.com/graysky2/kernel_gcc_patch/ Desc: Kernel patch enables gcc < v4.9 optimizations for additional CPUs. +Patch: 5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.6.patch +From: http://algo.ing.unimo.it/people/paolo/disk_sched/ +Desc: BFQ v7r11 patch 1 for 4.6: Build, cgroups and kconfig bits + +Patch: 5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.6.patch1 +From: http://algo.ing.unimo.it/people/paolo/disk_sched/ +Desc: BFQ v7r11 patch 2 for 4.6: BFQ Scheduler + +Patch: 5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.6.patch +From: http://algo.ing.unimo.it/people/paolo/disk_sched/ +Desc: BFQ v7r11 patch 3 for 4.6: Early Queue Merge (EQM) + +Patch: 5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch2 +From: http://algo.ing.unimo.it/people/paolo/disk_sched/ +Desc: BFQ v7r11 patch 4 for 4.7: Early Queue Merge (EQM) + Patch: 5010_enable-additional-cpu-optimizations-for-gcc-4.9.patch From: https://github.com/graysky2/kernel_gcc_patch/ Desc: Kernel patch enables gcc >= v4.9 optimizations for additional CPUs. diff --git a/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.6.patch b/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.6.patch new file mode 100644 index 0000000..ee3934f --- /dev/null +++ b/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.6.patch @@ -0,0 +1,103 @@ +From 4cf5d043709bfe73b4553272706cb5beb8072301 Mon Sep 17 00:00:00 2001 +From: Paolo Valente +Date: Tue, 7 Apr 2015 13:39:12 +0200 +Subject: [PATCH 1/4] block: cgroups, kconfig, build bits for BFQ-v7r11-4.6.0 + +Update Kconfig.iosched and do the related Makefile changes to include +kernel configuration options for BFQ. Also increase the number of +policies supported by the blkio controller so that BFQ can add its +own. + +Signed-off-by: Paolo Valente +Signed-off-by: Arianna Avanzini +--- + block/Kconfig.iosched | 32 ++++++++++++++++++++++++++++++++ + block/Makefile | 1 + + include/linux/blkdev.h | 2 +- + 3 files changed, 34 insertions(+), 1 deletion(-) + +diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched +index 421bef9..0ee5f0f 100644 +--- a/block/Kconfig.iosched ++++ b/block/Kconfig.iosched +@@ -39,6 +39,27 @@ config CFQ_GROUP_IOSCHED + ---help--- + Enable group IO scheduling in CFQ. + ++config IOSCHED_BFQ ++ tristate "BFQ I/O scheduler" ++ default n ++ ---help--- ++ The BFQ I/O scheduler tries to distribute bandwidth among ++ all processes according to their weights. ++ It aims at distributing the bandwidth as desired, independently of ++ the disk parameters and with any workload. It also tries to ++ guarantee low latency to interactive and soft real-time ++ applications. If compiled built-in (saying Y here), BFQ can ++ be configured to support hierarchical scheduling. ++ ++config CGROUP_BFQIO ++ bool "BFQ hierarchical scheduling support" ++ depends on CGROUPS && IOSCHED_BFQ=y ++ default n ++ ---help--- ++ Enable hierarchical scheduling in BFQ, using the cgroups ++ filesystem interface. The name of the subsystem will be ++ bfqio. ++ + choice + prompt "Default I/O scheduler" + default DEFAULT_CFQ +@@ -52,6 +73,16 @@ choice + config DEFAULT_CFQ + bool "CFQ" if IOSCHED_CFQ=y + ++ config DEFAULT_BFQ ++ bool "BFQ" if IOSCHED_BFQ=y ++ help ++ Selects BFQ as the default I/O scheduler which will be ++ used by default for all block devices. ++ The BFQ I/O scheduler aims at distributing the bandwidth ++ as desired, independently of the disk parameters and with ++ any workload. It also tries to guarantee low latency to ++ interactive and soft real-time applications. ++ + config DEFAULT_NOOP + bool "No-op" + +@@ -61,6 +92,7 @@ config DEFAULT_IOSCHED + string + default "deadline" if DEFAULT_DEADLINE + default "cfq" if DEFAULT_CFQ ++ default "bfq" if DEFAULT_BFQ + default "noop" if DEFAULT_NOOP + + endmenu +diff --git a/block/Makefile b/block/Makefile +index 9eda232..4a36683 100644 +--- a/block/Makefile ++++ b/block/Makefile +@@ -18,6 +18,7 @@ obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o + obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o + obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o + obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o ++obj-$(CONFIG_IOSCHED_BFQ) += bfq-iosched.o + + obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o + obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o +diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h +index 669e419..119be87 100644 +--- a/include/linux/blkdev.h ++++ b/include/linux/blkdev.h +@@ -45,7 +45,7 @@ struct pr_ops; + * Maximum number of blkcg policies allowed to be registered concurrently. + * Defined here to simplify include dependency. + */ +-#define BLKCG_MAX_POLS 2 ++#define BLKCG_MAX_POLS 3 + + struct request; + typedef void (rq_end_io_fn)(struct request *, int); +-- +1.9.1 + diff --git a/5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.6.patch1 b/5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.6.patch1 new file mode 100644 index 0000000..c232a83 --- /dev/null +++ b/5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.6.patch1 @@ -0,0 +1,7097 @@ +From 75c0230fa4f82fb77e41cf60c06e22b5e07f7f97 Mon Sep 17 00:00:00 2001 +From: Paolo Valente +Date: Thu, 9 May 2013 19:10:02 +0200 +Subject: [PATCH 2/4] block: introduce the BFQ-v7r11 I/O sched for 4.6.0 + +The general structure is borrowed from CFQ, as much of the code for +handling I/O contexts. Over time, several useful features have been +ported from CFQ as well (details in the changelog in README.BFQ). A +(bfq_)queue is associated to each task doing I/O on a device, and each +time a scheduling decision has to be made a queue is selected and served +until it expires. + + - Slices are given in the service domain: tasks are assigned + budgets, measured in number of sectors. Once got the disk, a task + must however consume its assigned budget within a configurable + maximum time (by default, the maximum possible value of the + budgets is automatically computed to comply with this timeout). + This allows the desired latency vs "throughput boosting" tradeoff + to be set. + + - Budgets are scheduled according to a variant of WF2Q+, implemented + using an augmented rb-tree to take eligibility into account while + preserving an O(log N) overall complexity. + + - A low-latency tunable is provided; if enabled, both interactive + and soft real-time applications are guaranteed a very low latency. + + - Latency guarantees are preserved also in the presence of NCQ. + + - Also with flash-based devices, a high throughput is achieved + while still preserving latency guarantees. + + - BFQ features Early Queue Merge (EQM), a sort of fusion of the + cooperating-queue-merging and the preemption mechanisms present + in CFQ. EQM is in fact a unified mechanism that tries to get a + sequential read pattern, and hence a high throughput, with any + set of processes performing interleaved I/O over a contiguous + sequence of sectors. + + - BFQ supports full hierarchical scheduling, exporting a cgroups + interface. Since each node has a full scheduler, each group can + be assigned its own weight. + + - If the cgroups interface is not used, only I/O priorities can be + assigned to processes, with ioprio values mapped to weights + with the relation weight = IOPRIO_BE_NR - ioprio. + + - ioprio classes are served in strict priority order, i.e., lower + priority queues are not served as long as there are higher + priority queues. Among queues in the same class the bandwidth is + distributed in proportion to the weight of each queue. A very + thin extra bandwidth is however guaranteed to the Idle class, to + prevent it from starving. + +Signed-off-by: Paolo Valente +Signed-off-by: Arianna Avanzini +--- + block/Kconfig.iosched | 6 +- + block/bfq-cgroup.c | 1182 ++++++++++++++++ + block/bfq-ioc.c | 36 + + block/bfq-iosched.c | 3754 +++++++++++++++++++++++++++++++++++++++++++++++++ + block/bfq-sched.c | 1200 ++++++++++++++++ + block/bfq.h | 801 +++++++++++ + 6 files changed, 6975 insertions(+), 4 deletions(-) + create mode 100644 block/bfq-cgroup.c + create mode 100644 block/bfq-ioc.c + create mode 100644 block/bfq-iosched.c + create mode 100644 block/bfq-sched.c + create mode 100644 block/bfq.h + +diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched +index 0ee5f0f..f78cd1a 100644 +--- a/block/Kconfig.iosched ++++ b/block/Kconfig.iosched +@@ -51,14 +51,12 @@ config IOSCHED_BFQ + applications. If compiled built-in (saying Y here), BFQ can + be configured to support hierarchical scheduling. + +-config CGROUP_BFQIO ++config BFQ_GROUP_IOSCHED + bool "BFQ hierarchical scheduling support" + depends on CGROUPS && IOSCHED_BFQ=y + default n + ---help--- +- Enable hierarchical scheduling in BFQ, using the cgroups +- filesystem interface. The name of the subsystem will be +- bfqio. ++ Enable hierarchical scheduling in BFQ, using the blkio controller. + + choice + prompt "Default I/O scheduler" +diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c +new file mode 100644 +index 0000000..8610cd6 +--- /dev/null ++++ b/block/bfq-cgroup.c +@@ -0,0 +1,1182 @@ ++/* ++ * BFQ: CGROUPS support. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ * ++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ ++ * file. ++ */ ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ ++/* bfqg stats flags */ ++enum bfqg_stats_flags { ++ BFQG_stats_waiting = 0, ++ BFQG_stats_idling, ++ BFQG_stats_empty, ++}; ++ ++#define BFQG_FLAG_FNS(name) \ ++static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \ ++{ \ ++ stats->flags |= (1 << BFQG_stats_##name); \ ++} \ ++static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \ ++{ \ ++ stats->flags &= ~(1 << BFQG_stats_##name); \ ++} \ ++static int bfqg_stats_##name(struct bfqg_stats *stats) \ ++{ \ ++ return (stats->flags & (1 << BFQG_stats_##name)) != 0; \ ++} \ ++ ++BFQG_FLAG_FNS(waiting) ++BFQG_FLAG_FNS(idling) ++BFQG_FLAG_FNS(empty) ++#undef BFQG_FLAG_FNS ++ ++/* This should be called with the queue_lock held. */ ++static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats) ++{ ++ unsigned long long now; ++ ++ if (!bfqg_stats_waiting(stats)) ++ return; ++ ++ now = sched_clock(); ++ if (time_after64(now, stats->start_group_wait_time)) ++ blkg_stat_add(&stats->group_wait_time, ++ now - stats->start_group_wait_time); ++ bfqg_stats_clear_waiting(stats); ++} ++ ++/* This should be called with the queue_lock held. */ ++static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, ++ struct bfq_group *curr_bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ if (bfqg_stats_waiting(stats)) ++ return; ++ if (bfqg == curr_bfqg) ++ return; ++ stats->start_group_wait_time = sched_clock(); ++ bfqg_stats_mark_waiting(stats); ++} ++ ++/* This should be called with the queue_lock held. */ ++static void bfqg_stats_end_empty_time(struct bfqg_stats *stats) ++{ ++ unsigned long long now; ++ ++ if (!bfqg_stats_empty(stats)) ++ return; ++ ++ now = sched_clock(); ++ if (time_after64(now, stats->start_empty_time)) ++ blkg_stat_add(&stats->empty_time, ++ now - stats->start_empty_time); ++ bfqg_stats_clear_empty(stats); ++} ++ ++static void bfqg_stats_update_dequeue(struct bfq_group *bfqg) ++{ ++ blkg_stat_add(&bfqg->stats.dequeue, 1); ++} ++ ++static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ if (blkg_rwstat_total(&stats->queued)) ++ return; ++ ++ /* ++ * group is already marked empty. This can happen if bfqq got new ++ * request in parent group and moved to this group while being added ++ * to service tree. Just ignore the event and move on. ++ */ ++ if (bfqg_stats_empty(stats)) ++ return; ++ ++ stats->start_empty_time = sched_clock(); ++ bfqg_stats_mark_empty(stats); ++} ++ ++static void bfqg_stats_update_idle_time(struct bfq_group *bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ if (bfqg_stats_idling(stats)) { ++ unsigned long long now = sched_clock(); ++ ++ if (time_after64(now, stats->start_idle_time)) ++ blkg_stat_add(&stats->idle_time, ++ now - stats->start_idle_time); ++ bfqg_stats_clear_idling(stats); ++ } ++} ++ ++static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ stats->start_idle_time = sched_clock(); ++ bfqg_stats_mark_idling(stats); ++} ++ ++static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ ++ blkg_stat_add(&stats->avg_queue_size_sum, ++ blkg_rwstat_total(&stats->queued)); ++ blkg_stat_add(&stats->avg_queue_size_samples, 1); ++ bfqg_stats_update_group_wait_time(stats); ++} ++ ++static struct blkcg_policy blkcg_policy_bfq; ++ ++/* ++ * blk-cgroup policy-related handlers ++ * The following functions help in converting between blk-cgroup ++ * internal structures and BFQ-specific structures. ++ */ ++ ++static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd) ++{ ++ return pd ? container_of(pd, struct bfq_group, pd) : NULL; ++} ++ ++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg) ++{ ++ return pd_to_blkg(&bfqg->pd); ++} ++ ++static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg) ++{ ++ struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq); ++ BUG_ON(!pd); ++ return pd_to_bfqg(pd); ++} ++ ++/* ++ * bfq_group handlers ++ * The following functions help in navigating the bfq_group hierarchy ++ * by allowing to find the parent of a bfq_group or the bfq_group ++ * associated to a bfq_queue. ++ */ ++ ++static struct bfq_group *bfqg_parent(struct bfq_group *bfqg) ++{ ++ struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent; ++ ++ return pblkg ? blkg_to_bfqg(pblkg) : NULL; ++} ++ ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *group_entity = bfqq->entity.parent; ++ ++ return group_entity ? container_of(group_entity, struct bfq_group, ++ entity) : ++ bfqq->bfqd->root_group; ++} ++ ++/* ++ * The following two functions handle get and put of a bfq_group by ++ * wrapping the related blk-cgroup hooks. ++ */ ++ ++static void bfqg_get(struct bfq_group *bfqg) ++{ ++ return blkg_get(bfqg_to_blkg(bfqg)); ++} ++ ++static void bfqg_put(struct bfq_group *bfqg) ++{ ++ return blkg_put(bfqg_to_blkg(bfqg)); ++} ++ ++static void bfqg_stats_update_io_add(struct bfq_group *bfqg, ++ struct bfq_queue *bfqq, ++ int rw) ++{ ++ blkg_rwstat_add(&bfqg->stats.queued, rw, 1); ++ bfqg_stats_end_empty_time(&bfqg->stats); ++ if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue)) ++ bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq)); ++} ++ ++static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, int rw) ++{ ++ blkg_rwstat_add(&bfqg->stats.queued, rw, -1); ++} ++ ++static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, int rw) ++{ ++ blkg_rwstat_add(&bfqg->stats.merged, rw, 1); ++} ++ ++static void bfqg_stats_update_dispatch(struct bfq_group *bfqg, ++ uint64_t bytes, int rw) ++{ ++ blkg_stat_add(&bfqg->stats.sectors, bytes >> 9); ++ blkg_rwstat_add(&bfqg->stats.serviced, rw, 1); ++ blkg_rwstat_add(&bfqg->stats.service_bytes, rw, bytes); ++} ++ ++static void bfqg_stats_update_completion(struct bfq_group *bfqg, ++ uint64_t start_time, uint64_t io_start_time, int rw) ++{ ++ struct bfqg_stats *stats = &bfqg->stats; ++ unsigned long long now = sched_clock(); ++ ++ if (time_after64(now, io_start_time)) ++ blkg_rwstat_add(&stats->service_time, rw, now - io_start_time); ++ if (time_after64(io_start_time, start_time)) ++ blkg_rwstat_add(&stats->wait_time, rw, ++ io_start_time - start_time); ++} ++ ++/* @stats = 0 */ ++static void bfqg_stats_reset(struct bfqg_stats *stats) ++{ ++ if (!stats) ++ return; ++ ++ /* queued stats shouldn't be cleared */ ++ blkg_rwstat_reset(&stats->service_bytes); ++ blkg_rwstat_reset(&stats->serviced); ++ blkg_rwstat_reset(&stats->merged); ++ blkg_rwstat_reset(&stats->service_time); ++ blkg_rwstat_reset(&stats->wait_time); ++ blkg_stat_reset(&stats->time); ++ blkg_stat_reset(&stats->unaccounted_time); ++ blkg_stat_reset(&stats->avg_queue_size_sum); ++ blkg_stat_reset(&stats->avg_queue_size_samples); ++ blkg_stat_reset(&stats->dequeue); ++ blkg_stat_reset(&stats->group_wait_time); ++ blkg_stat_reset(&stats->idle_time); ++ blkg_stat_reset(&stats->empty_time); ++} ++ ++/* @to += @from */ ++static void bfqg_stats_merge(struct bfqg_stats *to, struct bfqg_stats *from) ++{ ++ if (!to || !from) ++ return; ++ ++ /* queued stats shouldn't be cleared */ ++ blkg_rwstat_add_aux(&to->service_bytes, &from->service_bytes); ++ blkg_rwstat_add_aux(&to->serviced, &from->serviced); ++ blkg_rwstat_add_aux(&to->merged, &from->merged); ++ blkg_rwstat_add_aux(&to->service_time, &from->service_time); ++ blkg_rwstat_add_aux(&to->wait_time, &from->wait_time); ++ blkg_stat_add_aux(&from->time, &from->time); ++ blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time); ++ blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum); ++ blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples); ++ blkg_stat_add_aux(&to->dequeue, &from->dequeue); ++ blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time); ++ blkg_stat_add_aux(&to->idle_time, &from->idle_time); ++ blkg_stat_add_aux(&to->empty_time, &from->empty_time); ++} ++ ++/* ++ * Transfer @bfqg's stats to its parent's dead_stats so that the ancestors' ++ * recursive stats can still account for the amount used by this bfqg after ++ * it's gone. ++ */ ++static void bfqg_stats_xfer_dead(struct bfq_group *bfqg) ++{ ++ struct bfq_group *parent; ++ ++ if (!bfqg) /* root_group */ ++ return; ++ ++ parent = bfqg_parent(bfqg); ++ ++ lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock); ++ ++ if (unlikely(!parent)) ++ return; ++ ++ bfqg_stats_merge(&parent->dead_stats, &bfqg->stats); ++ bfqg_stats_merge(&parent->dead_stats, &bfqg->dead_stats); ++ bfqg_stats_reset(&bfqg->stats); ++ bfqg_stats_reset(&bfqg->dead_stats); ++} ++ ++static void bfq_init_entity(struct bfq_entity *entity, ++ struct bfq_group *bfqg) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ entity->weight = entity->new_weight; ++ entity->orig_weight = entity->new_weight; ++ if (bfqq) { ++ bfqq->ioprio = bfqq->new_ioprio; ++ bfqq->ioprio_class = bfqq->new_ioprio_class; ++ bfqg_get(bfqg); ++ } ++ entity->parent = bfqg->my_entity; ++ entity->sched_data = &bfqg->sched_data; ++} ++ ++static void bfqg_stats_exit(struct bfqg_stats *stats) ++{ ++ blkg_rwstat_exit(&stats->service_bytes); ++ blkg_rwstat_exit(&stats->serviced); ++ blkg_rwstat_exit(&stats->merged); ++ blkg_rwstat_exit(&stats->service_time); ++ blkg_rwstat_exit(&stats->wait_time); ++ blkg_rwstat_exit(&stats->queued); ++ blkg_stat_exit(&stats->sectors); ++ blkg_stat_exit(&stats->time); ++ blkg_stat_exit(&stats->unaccounted_time); ++ blkg_stat_exit(&stats->avg_queue_size_sum); ++ blkg_stat_exit(&stats->avg_queue_size_samples); ++ blkg_stat_exit(&stats->dequeue); ++ blkg_stat_exit(&stats->group_wait_time); ++ blkg_stat_exit(&stats->idle_time); ++ blkg_stat_exit(&stats->empty_time); ++} ++ ++static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) ++{ ++ if (blkg_rwstat_init(&stats->service_bytes, gfp) || ++ blkg_rwstat_init(&stats->serviced, gfp) || ++ blkg_rwstat_init(&stats->merged, gfp) || ++ blkg_rwstat_init(&stats->service_time, gfp) || ++ blkg_rwstat_init(&stats->wait_time, gfp) || ++ blkg_rwstat_init(&stats->queued, gfp) || ++ blkg_stat_init(&stats->sectors, gfp) || ++ blkg_stat_init(&stats->time, gfp) || ++ blkg_stat_init(&stats->unaccounted_time, gfp) || ++ blkg_stat_init(&stats->avg_queue_size_sum, gfp) || ++ blkg_stat_init(&stats->avg_queue_size_samples, gfp) || ++ blkg_stat_init(&stats->dequeue, gfp) || ++ blkg_stat_init(&stats->group_wait_time, gfp) || ++ blkg_stat_init(&stats->idle_time, gfp) || ++ blkg_stat_init(&stats->empty_time, gfp)) { ++ bfqg_stats_exit(stats); ++ return -ENOMEM; ++ } ++ ++ return 0; ++} ++ ++static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd) ++ { ++ return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL; ++ } ++ ++static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg) ++{ ++ return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq)); ++} ++ ++static void bfq_cpd_init(struct blkcg_policy_data *cpd) ++{ ++ struct bfq_group_data *d = cpd_to_bfqgd(cpd); ++ ++ d->weight = BFQ_DEFAULT_GRP_WEIGHT; ++} ++ ++static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) ++{ ++ struct bfq_group *bfqg; ++ ++ bfqg = kzalloc_node(sizeof(*bfqg), gfp, node); ++ if (!bfqg) ++ return NULL; ++ ++ if (bfqg_stats_init(&bfqg->stats, gfp) || ++ bfqg_stats_init(&bfqg->dead_stats, gfp)) { ++ kfree(bfqg); ++ return NULL; ++ } ++ ++ return &bfqg->pd; ++} ++ ++static void bfq_group_set_parent(struct bfq_group *bfqg, ++ struct bfq_group *parent) ++{ ++ struct bfq_entity *entity; ++ ++ BUG_ON(!parent); ++ BUG_ON(!bfqg); ++ BUG_ON(bfqg == parent); ++ ++ entity = &bfqg->entity; ++ entity->parent = parent->my_entity; ++ entity->sched_data = &parent->sched_data; ++} ++ ++static void bfq_pd_init(struct blkg_policy_data *pd) ++{ ++ struct blkcg_gq *blkg = pd_to_blkg(pd); ++ struct bfq_group *bfqg = blkg_to_bfqg(blkg); ++ struct bfq_data *bfqd = blkg->q->elevator->elevator_data; ++ struct bfq_entity *entity = &bfqg->entity; ++ struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg); ++ ++ entity->orig_weight = entity->weight = entity->new_weight = d->weight; ++ entity->my_sched_data = &bfqg->sched_data; ++ bfqg->my_entity = entity; /* ++ * the root_group's will be set to NULL ++ * in bfq_init_queue() ++ */ ++ bfqg->bfqd = bfqd; ++ bfqg->active_entities = 0; ++} ++ ++static void bfq_pd_free(struct blkg_policy_data *pd) ++{ ++ struct bfq_group *bfqg = pd_to_bfqg(pd); ++ ++ bfqg_stats_exit(&bfqg->stats); ++ bfqg_stats_exit(&bfqg->dead_stats); ++ ++ return kfree(bfqg); ++} ++ ++/* offset delta from bfqg->stats to bfqg->dead_stats */ ++static const int dead_stats_off_delta = offsetof(struct bfq_group, dead_stats) - ++ offsetof(struct bfq_group, stats); ++ ++/* to be used by recursive prfill, sums live and dead stats recursively */ ++static u64 bfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off) ++{ ++ u64 sum = 0; ++ ++ sum += blkg_stat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off); ++ sum += blkg_stat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, ++ off + dead_stats_off_delta); ++ return sum; ++} ++ ++/* to be used by recursive prfill, sums live and dead rwstats recursively */ ++static struct blkg_rwstat bfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd, ++ int off) ++{ ++ struct blkg_rwstat a, b; ++ ++ a = blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off); ++ b = blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, ++ off + dead_stats_off_delta); ++ blkg_rwstat_add_aux(&a, &b); ++ return a; ++} ++ ++static void bfq_pd_reset_stats(struct blkg_policy_data *pd) ++{ ++ struct bfq_group *bfqg = pd_to_bfqg(pd); ++ ++ bfqg_stats_reset(&bfqg->stats); ++ bfqg_stats_reset(&bfqg->dead_stats); ++} ++ ++static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd, ++ struct blkcg *blkcg) ++{ ++ struct request_queue *q = bfqd->queue; ++ struct bfq_group *bfqg = NULL, *parent; ++ struct bfq_entity *entity = NULL; ++ ++ assert_spin_locked(bfqd->queue->queue_lock); ++ ++ /* avoid lookup for the common case where there's no blkcg */ ++ if (blkcg == &blkcg_root) { ++ bfqg = bfqd->root_group; ++ } else { ++ struct blkcg_gq *blkg; ++ ++ blkg = blkg_lookup_create(blkcg, q); ++ if (!IS_ERR(blkg)) ++ bfqg = blkg_to_bfqg(blkg); ++ else /* fallback to root_group */ ++ bfqg = bfqd->root_group; ++ } ++ ++ BUG_ON(!bfqg); ++ ++ /* ++ * Update chain of bfq_groups as we might be handling a leaf group ++ * which, along with some of its relatives, has not been hooked yet ++ * to the private hierarchy of BFQ. ++ */ ++ entity = &bfqg->entity; ++ for_each_entity(entity) { ++ bfqg = container_of(entity, struct bfq_group, entity); ++ BUG_ON(!bfqg); ++ if (bfqg != bfqd->root_group) { ++ parent = bfqg_parent(bfqg); ++ if (!parent) ++ parent = bfqd->root_group; ++ BUG_ON(!parent); ++ bfq_group_set_parent(bfqg, parent); ++ } ++ } ++ ++ return bfqg; ++} ++ ++/** ++ * bfq_bfqq_move - migrate @bfqq to @bfqg. ++ * @bfqd: queue descriptor. ++ * @bfqq: the queue to move. ++ * @entity: @bfqq's entity. ++ * @bfqg: the group to move to. ++ * ++ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating ++ * it on the new one. Avoid putting the entity on the old group idle tree. ++ * ++ * Must be called under the queue lock; the cgroup owning @bfqg must ++ * not disappear (by now this just means that we are called under ++ * rcu_read_lock()). ++ */ ++static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct bfq_entity *entity, struct bfq_group *bfqg) ++{ ++ int busy, resume; ++ ++ busy = bfq_bfqq_busy(bfqq); ++ resume = !RB_EMPTY_ROOT(&bfqq->sort_list); ++ ++ BUG_ON(resume && !entity->on_st); ++ BUG_ON(busy && !resume && entity->on_st && ++ bfqq != bfqd->in_service_queue); ++ ++ if (busy) { ++ BUG_ON(atomic_read(&bfqq->ref) < 2); ++ ++ if (!resume) ++ bfq_del_bfqq_busy(bfqd, bfqq, 0); ++ else ++ bfq_deactivate_bfqq(bfqd, bfqq, 0); ++ } else if (entity->on_st) ++ bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); ++ bfqg_put(bfqq_group(bfqq)); ++ ++ /* ++ * Here we use a reference to bfqg. We don't need a refcounter ++ * as the cgroup reference will not be dropped, so that its ++ * destroy() callback will not be invoked. ++ */ ++ entity->parent = bfqg->my_entity; ++ entity->sched_data = &bfqg->sched_data; ++ bfqg_get(bfqg); ++ ++ if (busy) { ++ if (resume) ++ bfq_activate_bfqq(bfqd, bfqq); ++ } ++ ++ if (!bfqd->in_service_queue && !bfqd->rq_in_driver) ++ bfq_schedule_dispatch(bfqd); ++} ++ ++/** ++ * __bfq_bic_change_cgroup - move @bic to @cgroup. ++ * @bfqd: the queue descriptor. ++ * @bic: the bic to move. ++ * @blkcg: the blk-cgroup to move to. ++ * ++ * Move bic to blkcg, assuming that bfqd->queue is locked; the caller ++ * has to make sure that the reference to cgroup is valid across the call. ++ * ++ * NOTE: an alternative approach might have been to store the current ++ * cgroup in bfqq and getting a reference to it, reducing the lookup ++ * time here, at the price of slightly more complex code. ++ */ ++static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, ++ struct bfq_io_cq *bic, ++ struct blkcg *blkcg) ++{ ++ struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0); ++ struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1); ++ struct bfq_group *bfqg; ++ struct bfq_entity *entity; ++ ++ lockdep_assert_held(bfqd->queue->queue_lock); ++ ++ bfqg = bfq_find_alloc_group(bfqd, blkcg); ++ if (async_bfqq) { ++ entity = &async_bfqq->entity; ++ ++ if (entity->sched_data != &bfqg->sched_data) { ++ bic_set_bfqq(bic, NULL, 0); ++ bfq_log_bfqq(bfqd, async_bfqq, ++ "bic_change_group: %p %d", ++ async_bfqq, atomic_read(&async_bfqq->ref)); ++ bfq_put_queue(async_bfqq); ++ } ++ } ++ ++ if (sync_bfqq) { ++ entity = &sync_bfqq->entity; ++ if (entity->sched_data != &bfqg->sched_data) ++ bfq_bfqq_move(bfqd, sync_bfqq, entity, bfqg); ++ } ++ ++ return bfqg; ++} ++ ++static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) ++{ ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ struct blkcg *blkcg; ++ struct bfq_group *bfqg = NULL; ++ uint64_t id; ++ ++ rcu_read_lock(); ++ blkcg = bio_blkcg(bio); ++ id = blkcg->css.serial_nr; ++ rcu_read_unlock(); ++ ++ /* ++ * Check whether blkcg has changed. The condition may trigger ++ * spuriously on a newly created cic but there's no harm. ++ */ ++ if (unlikely(!bfqd) || likely(bic->blkcg_id == id)) ++ return; ++ ++ bfqg = __bfq_bic_change_cgroup(bfqd, bic, blkcg); ++ BUG_ON(!bfqg); ++ bic->blkcg_id = id; ++} ++ ++/** ++ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st. ++ * @st: the service tree being flushed. ++ */ ++static void bfq_flush_idle_tree(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *entity = st->first_idle; ++ ++ for (; entity ; entity = st->first_idle) ++ __bfq_deactivate_entity(entity, 0); ++} ++ ++/** ++ * bfq_reparent_leaf_entity - move leaf entity to the root_group. ++ * @bfqd: the device data structure with the root group. ++ * @entity: the entity to move. ++ */ ++static void bfq_reparent_leaf_entity(struct bfq_data *bfqd, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ BUG_ON(!bfqq); ++ bfq_bfqq_move(bfqd, bfqq, entity, bfqd->root_group); ++ return; ++} ++ ++/** ++ * bfq_reparent_active_entities - move to the root group all active ++ * entities. ++ * @bfqd: the device data structure with the root group. ++ * @bfqg: the group to move from. ++ * @st: the service tree with the entities. ++ * ++ * Needs queue_lock to be taken and reference to be valid over the call. ++ */ ++static void bfq_reparent_active_entities(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, ++ struct bfq_service_tree *st) ++{ ++ struct rb_root *active = &st->active; ++ struct bfq_entity *entity = NULL; ++ ++ if (!RB_EMPTY_ROOT(&st->active)) ++ entity = bfq_entity_of(rb_first(active)); ++ ++ for (; entity ; entity = bfq_entity_of(rb_first(active))) ++ bfq_reparent_leaf_entity(bfqd, entity); ++ ++ if (bfqg->sched_data.in_service_entity) ++ bfq_reparent_leaf_entity(bfqd, ++ bfqg->sched_data.in_service_entity); ++ ++ return; ++} ++ ++/** ++ * bfq_destroy_group - destroy @bfqg. ++ * @bfqg: the group being destroyed. ++ * ++ * Destroy @bfqg, making sure that it is not referenced from its parent. ++ * blkio already grabs the queue_lock for us, so no need to use RCU-based magic ++ */ ++static void bfq_pd_offline(struct blkg_policy_data *pd) ++{ ++ struct bfq_service_tree *st; ++ struct bfq_group *bfqg; ++ struct bfq_data *bfqd; ++ struct bfq_entity *entity; ++ int i; ++ ++ BUG_ON(!pd); ++ bfqg = pd_to_bfqg(pd); ++ BUG_ON(!bfqg); ++ bfqd = bfqg->bfqd; ++ BUG_ON(bfqd && !bfqd->root_group); ++ ++ entity = bfqg->my_entity; ++ ++ if (!entity) /* root group */ ++ return; ++ ++ /* ++ * Empty all service_trees belonging to this group before ++ * deactivating the group itself. ++ */ ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) { ++ BUG_ON(!bfqg->sched_data.service_tree); ++ st = bfqg->sched_data.service_tree + i; ++ /* ++ * The idle tree may still contain bfq_queues belonging ++ * to exited task because they never migrated to a different ++ * cgroup from the one being destroyed now. No one else ++ * can access them so it's safe to act without any lock. ++ */ ++ bfq_flush_idle_tree(st); ++ ++ /* ++ * It may happen that some queues are still active ++ * (busy) upon group destruction (if the corresponding ++ * processes have been forced to terminate). We move ++ * all the leaf entities corresponding to these queues ++ * to the root_group. ++ * Also, it may happen that the group has an entity ++ * in service, which is disconnected from the active ++ * tree: it must be moved, too. ++ * There is no need to put the sync queues, as the ++ * scheduler has taken no reference. ++ */ ++ bfq_reparent_active_entities(bfqd, bfqg, st); ++ BUG_ON(!RB_EMPTY_ROOT(&st->active)); ++ BUG_ON(!RB_EMPTY_ROOT(&st->idle)); ++ } ++ BUG_ON(bfqg->sched_data.next_in_service); ++ BUG_ON(bfqg->sched_data.in_service_entity); ++ ++ __bfq_deactivate_entity(entity, 0); ++ bfq_put_async_queues(bfqd, bfqg); ++ BUG_ON(entity->tree); ++ ++ bfqg_stats_xfer_dead(bfqg); ++} ++ ++static void bfq_end_wr_async(struct bfq_data *bfqd) ++{ ++ struct blkcg_gq *blkg; ++ ++ list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) { ++ struct bfq_group *bfqg = blkg_to_bfqg(blkg); ++ ++ bfq_end_wr_async_queues(bfqd, bfqg); ++ } ++ bfq_end_wr_async_queues(bfqd, bfqd->root_group); ++} ++ ++static u64 bfqio_cgroup_weight_read(struct cgroup_subsys_state *css, ++ struct cftype *cftype) ++{ ++ struct blkcg *blkcg = css_to_blkcg(css); ++ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); ++ int ret = -EINVAL; ++ ++ spin_lock_irq(&blkcg->lock); ++ ret = bfqgd->weight; ++ spin_unlock_irq(&blkcg->lock); ++ ++ return ret; ++} ++ ++static int bfqio_cgroup_weight_read_dfl(struct seq_file *sf, void *v) ++{ ++ struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); ++ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); ++ ++ spin_lock_irq(&blkcg->lock); ++ seq_printf(sf, "%u\n", bfqgd->weight); ++ spin_unlock_irq(&blkcg->lock); ++ ++ return 0; ++} ++ ++static int bfqio_cgroup_weight_write(struct cgroup_subsys_state *css, ++ struct cftype *cftype, ++ u64 val) ++{ ++ struct blkcg *blkcg = css_to_blkcg(css); ++ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); ++ struct blkcg_gq *blkg; ++ int ret = -EINVAL; ++ ++ if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) ++ return ret; ++ ++ ret = 0; ++ spin_lock_irq(&blkcg->lock); ++ bfqgd->weight = (unsigned short)val; ++ hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { ++ struct bfq_group *bfqg = blkg_to_bfqg(blkg); ++ if (!bfqg) ++ continue; ++ /* ++ * Setting the prio_changed flag of the entity ++ * to 1 with new_weight == weight would re-set ++ * the value of the weight to its ioprio mapping. ++ * Set the flag only if necessary. ++ */ ++ if ((unsigned short)val != bfqg->entity.new_weight) { ++ bfqg->entity.new_weight = (unsigned short)val; ++ /* ++ * Make sure that the above new value has been ++ * stored in bfqg->entity.new_weight before ++ * setting the prio_changed flag. In fact, ++ * this flag may be read asynchronously (in ++ * critical sections protected by a different ++ * lock than that held here), and finding this ++ * flag set may cause the execution of the code ++ * for updating parameters whose value may ++ * depend also on bfqg->entity.new_weight (in ++ * __bfq_entity_update_weight_prio). ++ * This barrier makes sure that the new value ++ * of bfqg->entity.new_weight is correctly ++ * seen in that code. ++ */ ++ smp_wmb(); ++ bfqg->entity.prio_changed = 1; ++ } ++ } ++ spin_unlock_irq(&blkcg->lock); ++ ++ return ret; ++} ++ ++static ssize_t bfqio_cgroup_weight_write_dfl(struct kernfs_open_file *of, ++ char *buf, size_t nbytes, ++ loff_t off) ++{ ++ /* First unsigned long found in the file is used */ ++ return bfqio_cgroup_weight_write(of_css(of), NULL, ++ simple_strtoull(strim(buf), NULL, 0)); ++} ++ ++static int bfqg_print_stat(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat, ++ &blkcg_policy_bfq, seq_cft(sf)->private, false); ++ return 0; ++} ++ ++static int bfqg_print_rwstat(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat, ++ &blkcg_policy_bfq, seq_cft(sf)->private, true); ++ return 0; ++} ++ ++static u64 bfqg_prfill_stat_recursive(struct seq_file *sf, ++ struct blkg_policy_data *pd, int off) ++{ ++ u64 sum = bfqg_stat_pd_recursive_sum(pd, off); ++ ++ return __blkg_prfill_u64(sf, pd, sum); ++} ++ ++static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf, ++ struct blkg_policy_data *pd, int off) ++{ ++ struct blkg_rwstat sum = bfqg_rwstat_pd_recursive_sum(pd, off); ++ ++ return __blkg_prfill_rwstat(sf, pd, &sum); ++} ++ ++static int bfqg_print_stat_recursive(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_stat_recursive, &blkcg_policy_bfq, ++ seq_cft(sf)->private, false); ++ return 0; ++} ++ ++static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq, ++ seq_cft(sf)->private, true); ++ return 0; ++} ++ ++static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf, ++ struct blkg_policy_data *pd, int off) ++{ ++ struct bfq_group *bfqg = pd_to_bfqg(pd); ++ u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples); ++ u64 v = 0; ++ ++ if (samples) { ++ v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum); ++ v = div64_u64(v, samples); ++ } ++ __blkg_prfill_u64(sf, pd, v); ++ return 0; ++} ++ ++/* print avg_queue_size */ ++static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_avg_queue_size, &blkcg_policy_bfq, ++ 0, false); ++ return 0; ++} ++ ++static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) ++{ ++ int ret; ++ ++ ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq); ++ if (ret) ++ return NULL; ++ ++ return blkg_to_bfqg(bfqd->queue->root_blkg); ++} ++ ++static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp) ++{ ++ struct bfq_group_data *bgd; ++ ++ bgd = kzalloc(sizeof(*bgd), GFP_KERNEL); ++ if (!bgd) ++ return NULL; ++ return &bgd->pd; ++} ++ ++static void bfq_cpd_free(struct blkcg_policy_data *cpd) ++{ ++ kfree(cpd_to_bfqgd(cpd)); ++} ++ ++static struct cftype bfqio_files_dfl[] = { ++ { ++ .name = "weight", ++ .flags = CFTYPE_NOT_ON_ROOT, ++ .seq_show = bfqio_cgroup_weight_read_dfl, ++ .write = bfqio_cgroup_weight_write_dfl, ++ }, ++ {} /* terminate */ ++}; ++ ++static struct cftype bfqio_files[] = { ++ { ++ .name = "bfq.weight", ++ .read_u64 = bfqio_cgroup_weight_read, ++ .write_u64 = bfqio_cgroup_weight_write, ++ }, ++ /* statistics, cover only the tasks in the bfqg */ ++ { ++ .name = "bfq.time", ++ .private = offsetof(struct bfq_group, stats.time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = "bfq.sectors", ++ .private = offsetof(struct bfq_group, stats.sectors), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = "bfq.io_service_bytes", ++ .private = offsetof(struct bfq_group, stats.service_bytes), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ { ++ .name = "bfq.io_serviced", ++ .private = offsetof(struct bfq_group, stats.serviced), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ { ++ .name = "bfq.io_service_time", ++ .private = offsetof(struct bfq_group, stats.service_time), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ { ++ .name = "bfq.io_wait_time", ++ .private = offsetof(struct bfq_group, stats.wait_time), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ { ++ .name = "bfq.io_merged", ++ .private = offsetof(struct bfq_group, stats.merged), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ { ++ .name = "bfq.io_queued", ++ .private = offsetof(struct bfq_group, stats.queued), ++ .seq_show = bfqg_print_rwstat, ++ }, ++ ++ /* the same statictics which cover the bfqg and its descendants */ ++ { ++ .name = "bfq.time_recursive", ++ .private = offsetof(struct bfq_group, stats.time), ++ .seq_show = bfqg_print_stat_recursive, ++ }, ++ { ++ .name = "bfq.sectors_recursive", ++ .private = offsetof(struct bfq_group, stats.sectors), ++ .seq_show = bfqg_print_stat_recursive, ++ }, ++ { ++ .name = "bfq.io_service_bytes_recursive", ++ .private = offsetof(struct bfq_group, stats.service_bytes), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = "bfq.io_serviced_recursive", ++ .private = offsetof(struct bfq_group, stats.serviced), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = "bfq.io_service_time_recursive", ++ .private = offsetof(struct bfq_group, stats.service_time), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = "bfq.io_wait_time_recursive", ++ .private = offsetof(struct bfq_group, stats.wait_time), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = "bfq.io_merged_recursive", ++ .private = offsetof(struct bfq_group, stats.merged), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = "bfq.io_queued_recursive", ++ .private = offsetof(struct bfq_group, stats.queued), ++ .seq_show = bfqg_print_rwstat_recursive, ++ }, ++ { ++ .name = "bfq.avg_queue_size", ++ .seq_show = bfqg_print_avg_queue_size, ++ }, ++ { ++ .name = "bfq.group_wait_time", ++ .private = offsetof(struct bfq_group, stats.group_wait_time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = "bfq.idle_time", ++ .private = offsetof(struct bfq_group, stats.idle_time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = "bfq.empty_time", ++ .private = offsetof(struct bfq_group, stats.empty_time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = "bfq.dequeue", ++ .private = offsetof(struct bfq_group, stats.dequeue), ++ .seq_show = bfqg_print_stat, ++ }, ++ { ++ .name = "bfq.unaccounted_time", ++ .private = offsetof(struct bfq_group, stats.unaccounted_time), ++ .seq_show = bfqg_print_stat, ++ }, ++ { } /* terminate */ ++}; ++ ++static struct blkcg_policy blkcg_policy_bfq = { ++ .dfl_cftypes = bfqio_files_dfl, ++ .legacy_cftypes = bfqio_files, ++ ++ .pd_alloc_fn = bfq_pd_alloc, ++ .pd_init_fn = bfq_pd_init, ++ .pd_offline_fn = bfq_pd_offline, ++ .pd_free_fn = bfq_pd_free, ++ .pd_reset_stats_fn = bfq_pd_reset_stats, ++ ++ .cpd_alloc_fn = bfq_cpd_alloc, ++ .cpd_init_fn = bfq_cpd_init, ++ .cpd_bind_fn = bfq_cpd_init, ++ .cpd_free_fn = bfq_cpd_free, ++ ++}; ++ ++#else ++ ++static void bfq_init_entity(struct bfq_entity *entity, ++ struct bfq_group *bfqg) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ entity->weight = entity->new_weight; ++ entity->orig_weight = entity->new_weight; ++ if (bfqq) { ++ bfqq->ioprio = bfqq->new_ioprio; ++ bfqq->ioprio_class = bfqq->new_ioprio_class; ++ } ++ entity->sched_data = &bfqg->sched_data; ++} ++ ++static struct bfq_group * ++bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) ++{ ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ return bfqd->root_group; ++} ++ ++static void bfq_bfqq_move(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct bfq_entity *entity, ++ struct bfq_group *bfqg) ++{ ++} ++ ++static void bfq_end_wr_async(struct bfq_data *bfqd) ++{ ++ bfq_end_wr_async_queues(bfqd, bfqd->root_group); ++} ++ ++static void bfq_disconnect_groups(struct bfq_data *bfqd) ++{ ++ bfq_put_async_queues(bfqd, bfqd->root_group); ++} ++ ++static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd, ++ struct blkcg *blkcg) ++{ ++ return bfqd->root_group; ++} ++ ++static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) ++{ ++ struct bfq_group *bfqg; ++ int i; ++ ++ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node); ++ if (!bfqg) ++ return NULL; ++ ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) ++ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; ++ ++ return bfqg; ++} ++#endif +diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c +new file mode 100644 +index 0000000..fb7bb8f +--- /dev/null ++++ b/block/bfq-ioc.c +@@ -0,0 +1,36 @@ ++/* ++ * BFQ: I/O context handling. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ */ ++ ++/** ++ * icq_to_bic - convert iocontext queue structure to bfq_io_cq. ++ * @icq: the iocontext queue. ++ */ ++static struct bfq_io_cq *icq_to_bic(struct io_cq *icq) ++{ ++ /* bic->icq is the first member, %NULL will convert to %NULL */ ++ return container_of(icq, struct bfq_io_cq, icq); ++} ++ ++/** ++ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd. ++ * @bfqd: the lookup key. ++ * @ioc: the io_context of the process doing I/O. ++ * ++ * Queue lock must be held. ++ */ ++static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd, ++ struct io_context *ioc) ++{ ++ if (ioc) ++ return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue)); ++ return NULL; ++} +diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c +new file mode 100644 +index 0000000..f9787a6 +--- /dev/null ++++ b/block/bfq-iosched.c +@@ -0,0 +1,3754 @@ ++/* ++ * Budget Fair Queueing (BFQ) disk scheduler. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ * ++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ ++ * file. ++ * ++ * BFQ is a proportional-share storage-I/O scheduling algorithm based on ++ * the slice-by-slice service scheme of CFQ. But BFQ assigns budgets, ++ * measured in number of sectors, to processes instead of time slices. The ++ * device is not granted to the in-service process for a given time slice, ++ * but until it has exhausted its assigned budget. This change from the time ++ * to the service domain allows BFQ to distribute the device throughput ++ * among processes as desired, without any distortion due to ZBR, workload ++ * fluctuations or other factors. BFQ uses an ad hoc internal scheduler, ++ * called B-WF2Q+, to schedule processes according to their budgets. More ++ * precisely, BFQ schedules queues associated to processes. Thanks to the ++ * accurate policy of B-WF2Q+, BFQ can afford to assign high budgets to ++ * I/O-bound processes issuing sequential requests (to boost the ++ * throughput), and yet guarantee a low latency to interactive and soft ++ * real-time applications. ++ * ++ * BFQ is described in [1], where also a reference to the initial, more ++ * theoretical paper on BFQ can be found. The interested reader can find ++ * in the latter paper full details on the main algorithm, as well as ++ * formulas of the guarantees and formal proofs of all the properties. ++ * With respect to the version of BFQ presented in these papers, this ++ * implementation adds a few more heuristics, such as the one that ++ * guarantees a low latency to soft real-time applications, and a ++ * hierarchical extension based on H-WF2Q+. ++ * ++ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with ++ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N) ++ * complexity derives from the one introduced with EEVDF in [3]. ++ * ++ * [1] P. Valente and M. Andreolini, ``Improving Application Responsiveness ++ * with the BFQ Disk I/O Scheduler'', ++ * Proceedings of the 5th Annual International Systems and Storage ++ * Conference (SYSTOR '12), June 2012. ++ * ++ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf ++ * ++ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing ++ * Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689, ++ * Oct 1997. ++ * ++ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz ++ * ++ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline ++ * First: A Flexible and Accurate Mechanism for Proportional Share ++ * Resource Allocation,'' technical report. ++ * ++ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf ++ */ ++#include ++#include ++#include ++#include ++#include ++#include ++#include ++#include ++#include "bfq.h" ++#include "blk.h" ++ ++/* Expiration time of sync (0) and async (1) requests, in jiffies. */ ++static const int bfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; ++ ++/* Maximum backwards seek, in KiB. */ ++static const int bfq_back_max = 16 * 1024; ++ ++/* Penalty of a backwards seek, in number of sectors. */ ++static const int bfq_back_penalty = 2; ++ ++/* Idling period duration, in jiffies. */ ++static int bfq_slice_idle = HZ / 125; ++ ++/* Minimum number of assigned budgets for which stats are safe to compute. */ ++static const int bfq_stats_min_budgets = 194; ++ ++/* Default maximum budget values, in sectors and number of requests. */ ++static const int bfq_default_max_budget = 16 * 1024; ++static const int bfq_max_budget_async_rq = 4; ++ ++/* ++ * Async to sync throughput distribution is controlled as follows: ++ * when an async request is served, the entity is charged the number ++ * of sectors of the request, multiplied by the factor below ++ */ ++static const int bfq_async_charge_factor = 10; ++ ++/* Default timeout values, in jiffies, approximating CFQ defaults. */ ++static const int bfq_timeout_sync = HZ / 8; ++static int bfq_timeout_async = HZ / 25; ++ ++struct kmem_cache *bfq_pool; ++ ++/* Below this threshold (in ms), we consider thinktime immediate. */ ++#define BFQ_MIN_TT 2 ++ ++/* hw_tag detection: parallel requests threshold and min samples needed. */ ++#define BFQ_HW_QUEUE_THRESHOLD 4 ++#define BFQ_HW_QUEUE_SAMPLES 32 ++ ++#define BFQQ_SEEK_THR (sector_t)(8 * 1024) ++#define BFQQ_SEEKY(bfqq) ((bfqq)->seek_mean > BFQQ_SEEK_THR) ++ ++/* Min samples used for peak rate estimation (for autotuning). */ ++#define BFQ_PEAK_RATE_SAMPLES 32 ++ ++/* Shift used for peak rate fixed precision calculations. */ ++#define BFQ_RATE_SHIFT 16 ++ ++/* ++ * By default, BFQ computes the duration of the weight raising for ++ * interactive applications automatically, using the following formula: ++ * duration = (R / r) * T, where r is the peak rate of the device, and ++ * R and T are two reference parameters. ++ * In particular, R is the peak rate of the reference device (see below), ++ * and T is a reference time: given the systems that are likely to be ++ * installed on the reference device according to its speed class, T is ++ * about the maximum time needed, under BFQ and while reading two files in ++ * parallel, to load typical large applications on these systems. ++ * In practice, the slower/faster the device at hand is, the more/less it ++ * takes to load applications with respect to the reference device. ++ * Accordingly, the longer/shorter BFQ grants weight raising to interactive ++ * applications. ++ * ++ * BFQ uses four different reference pairs (R, T), depending on: ++ * . whether the device is rotational or non-rotational; ++ * . whether the device is slow, such as old or portable HDDs, as well as ++ * SD cards, or fast, such as newer HDDs and SSDs. ++ * ++ * The device's speed class is dynamically (re)detected in ++ * bfq_update_peak_rate() every time the estimated peak rate is updated. ++ * ++ * In the following definitions, R_slow[0]/R_fast[0] and T_slow[0]/T_fast[0] ++ * are the reference values for a slow/fast rotational device, whereas ++ * R_slow[1]/R_fast[1] and T_slow[1]/T_fast[1] are the reference values for ++ * a slow/fast non-rotational device. Finally, device_speed_thresh are the ++ * thresholds used to switch between speed classes. ++ * Both the reference peak rates and the thresholds are measured in ++ * sectors/usec, left-shifted by BFQ_RATE_SHIFT. ++ */ ++static int R_slow[2] = {1536, 10752}; ++static int R_fast[2] = {17415, 34791}; ++/* ++ * To improve readability, a conversion function is used to initialize the ++ * following arrays, which entails that they can be initialized only in a ++ * function. ++ */ ++static int T_slow[2]; ++static int T_fast[2]; ++static int device_speed_thresh[2]; ++ ++#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \ ++ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 }) ++ ++#define RQ_BIC(rq) ((struct bfq_io_cq *) (rq)->elv.priv[0]) ++#define RQ_BFQQ(rq) ((rq)->elv.priv[1]) ++ ++static void bfq_schedule_dispatch(struct bfq_data *bfqd); ++ ++#include "bfq-ioc.c" ++#include "bfq-sched.c" ++#include "bfq-cgroup.c" ++ ++#define bfq_class_idle(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE) ++#define bfq_class_rt(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_RT) ++ ++#define bfq_sample_valid(samples) ((samples) > 80) ++ ++/* ++ * We regard a request as SYNC, if either it's a read or has the SYNC bit ++ * set (in which case it could also be a direct WRITE). ++ */ ++static int bfq_bio_sync(struct bio *bio) ++{ ++ if (bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC)) ++ return 1; ++ ++ return 0; ++} ++ ++/* ++ * Scheduler run of queue, if there are requests pending and no one in the ++ * driver that will restart queueing. ++ */ ++static void bfq_schedule_dispatch(struct bfq_data *bfqd) ++{ ++ if (bfqd->queued != 0) { ++ bfq_log(bfqd, "schedule dispatch"); ++ kblockd_schedule_work(&bfqd->unplug_work); ++ } ++} ++ ++/* ++ * Lifted from AS - choose which of rq1 and rq2 that is best served now. ++ * We choose the request that is closesr to the head right now. Distance ++ * behind the head is penalized and only allowed to a certain extent. ++ */ ++static struct request *bfq_choose_req(struct bfq_data *bfqd, ++ struct request *rq1, ++ struct request *rq2, ++ sector_t last) ++{ ++ sector_t s1, s2, d1 = 0, d2 = 0; ++ unsigned long back_max; ++#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */ ++#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */ ++ unsigned wrap = 0; /* bit mask: requests behind the disk head? */ ++ ++ if (!rq1 || rq1 == rq2) ++ return rq2; ++ if (!rq2) ++ return rq1; ++ ++ if (rq_is_sync(rq1) && !rq_is_sync(rq2)) ++ return rq1; ++ else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) ++ return rq2; ++ if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META)) ++ return rq1; ++ else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META)) ++ return rq2; ++ ++ s1 = blk_rq_pos(rq1); ++ s2 = blk_rq_pos(rq2); ++ ++ /* ++ * By definition, 1KiB is 2 sectors. ++ */ ++ back_max = bfqd->bfq_back_max * 2; ++ ++ /* ++ * Strict one way elevator _except_ in the case where we allow ++ * short backward seeks which are biased as twice the cost of a ++ * similar forward seek. ++ */ ++ if (s1 >= last) ++ d1 = s1 - last; ++ else if (s1 + back_max >= last) ++ d1 = (last - s1) * bfqd->bfq_back_penalty; ++ else ++ wrap |= BFQ_RQ1_WRAP; ++ ++ if (s2 >= last) ++ d2 = s2 - last; ++ else if (s2 + back_max >= last) ++ d2 = (last - s2) * bfqd->bfq_back_penalty; ++ else ++ wrap |= BFQ_RQ2_WRAP; ++ ++ /* Found required data */ ++ ++ /* ++ * By doing switch() on the bit mask "wrap" we avoid having to ++ * check two variables for all permutations: --> faster! ++ */ ++ switch (wrap) { ++ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ ++ if (d1 < d2) ++ return rq1; ++ else if (d2 < d1) ++ return rq2; ++ else { ++ if (s1 >= s2) ++ return rq1; ++ else ++ return rq2; ++ } ++ ++ case BFQ_RQ2_WRAP: ++ return rq1; ++ case BFQ_RQ1_WRAP: ++ return rq2; ++ case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */ ++ default: ++ /* ++ * Since both rqs are wrapped, ++ * start with the one that's further behind head ++ * (--> only *one* back seek required), ++ * since back seek takes more time than forward. ++ */ ++ if (s1 <= s2) ++ return rq1; ++ else ++ return rq2; ++ } ++} ++ ++/* ++ * Tell whether there are active queues or groups with differentiated weights. ++ */ ++static bool bfq_differentiated_weights(struct bfq_data *bfqd) ++{ ++ /* ++ * For weights to differ, at least one of the trees must contain ++ * at least two nodes. ++ */ ++ return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) && ++ (bfqd->queue_weights_tree.rb_node->rb_left || ++ bfqd->queue_weights_tree.rb_node->rb_right) ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ ) || ++ (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) && ++ (bfqd->group_weights_tree.rb_node->rb_left || ++ bfqd->group_weights_tree.rb_node->rb_right) ++#endif ++ ); ++} ++ ++/* ++ * The following function returns true if every queue must receive the ++ * same share of the throughput (this condition is used when deciding ++ * whether idling may be disabled, see the comments in the function ++ * bfq_bfqq_may_idle()). ++ * ++ * Such a scenario occurs when: ++ * 1) all active queues have the same weight, ++ * 2) all active groups at the same level in the groups tree have the same ++ * weight, ++ * 3) all active groups at the same level in the groups tree have the same ++ * number of children. ++ * ++ * Unfortunately, keeping the necessary state for evaluating exactly the ++ * above symmetry conditions would be quite complex and time-consuming. ++ * Therefore this function evaluates, instead, the following stronger ++ * sub-conditions, for which it is much easier to maintain the needed ++ * state: ++ * 1) all active queues have the same weight, ++ * 2) all active groups have the same weight, ++ * 3) all active groups have at most one active child each. ++ * In particular, the last two conditions are always true if hierarchical ++ * support and the cgroups interface are not enabled, thus no state needs ++ * to be maintained in this case. ++ */ ++static bool bfq_symmetric_scenario(struct bfq_data *bfqd) ++{ ++ return ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ !bfqd->active_numerous_groups && ++#endif ++ !bfq_differentiated_weights(bfqd); ++} ++ ++/* ++ * If the weight-counter tree passed as input contains no counter for ++ * the weight of the input entity, then add that counter; otherwise just ++ * increment the existing counter. ++ * ++ * Note that weight-counter trees contain few nodes in mostly symmetric ++ * scenarios. For example, if all queues have the same weight, then the ++ * weight-counter tree for the queues may contain at most one node. ++ * This holds even if low_latency is on, because weight-raised queues ++ * are not inserted in the tree. ++ * In most scenarios, the rate at which nodes are created/destroyed ++ * should be low too. ++ */ ++static void bfq_weights_tree_add(struct bfq_data *bfqd, ++ struct bfq_entity *entity, ++ struct rb_root *root) ++{ ++ struct rb_node **new = &(root->rb_node), *parent = NULL; ++ ++ /* ++ * Do not insert if the entity is already associated with a ++ * counter, which happens if: ++ * 1) the entity is associated with a queue, ++ * 2) a request arrival has caused the queue to become both ++ * non-weight-raised, and hence change its weight, and ++ * backlogged; in this respect, each of the two events ++ * causes an invocation of this function, ++ * 3) this is the invocation of this function caused by the ++ * second event. This second invocation is actually useless, ++ * and we handle this fact by exiting immediately. More ++ * efficient or clearer solutions might possibly be adopted. ++ */ ++ if (entity->weight_counter) ++ return; ++ ++ while (*new) { ++ struct bfq_weight_counter *__counter = container_of(*new, ++ struct bfq_weight_counter, ++ weights_node); ++ parent = *new; ++ ++ if (entity->weight == __counter->weight) { ++ entity->weight_counter = __counter; ++ goto inc_counter; ++ } ++ if (entity->weight < __counter->weight) ++ new = &((*new)->rb_left); ++ else ++ new = &((*new)->rb_right); ++ } ++ ++ entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter), ++ GFP_ATOMIC); ++ entity->weight_counter->weight = entity->weight; ++ rb_link_node(&entity->weight_counter->weights_node, parent, new); ++ rb_insert_color(&entity->weight_counter->weights_node, root); ++ ++inc_counter: ++ entity->weight_counter->num_active++; ++} ++ ++/* ++ * Decrement the weight counter associated with the entity, and, if the ++ * counter reaches 0, remove the counter from the tree. ++ * See the comments to the function bfq_weights_tree_add() for considerations ++ * about overhead. ++ */ ++static void bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_entity *entity, ++ struct rb_root *root) ++{ ++ if (!entity->weight_counter) ++ return; ++ ++ BUG_ON(RB_EMPTY_ROOT(root)); ++ BUG_ON(entity->weight_counter->weight != entity->weight); ++ ++ BUG_ON(!entity->weight_counter->num_active); ++ entity->weight_counter->num_active--; ++ if (entity->weight_counter->num_active > 0) ++ goto reset_entity_pointer; ++ ++ rb_erase(&entity->weight_counter->weights_node, root); ++ kfree(entity->weight_counter); ++ ++reset_entity_pointer: ++ entity->weight_counter = NULL; ++} ++ ++static struct request *bfq_find_next_rq(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct request *last) ++{ ++ struct rb_node *rbnext = rb_next(&last->rb_node); ++ struct rb_node *rbprev = rb_prev(&last->rb_node); ++ struct request *next = NULL, *prev = NULL; ++ ++ BUG_ON(RB_EMPTY_NODE(&last->rb_node)); ++ ++ if (rbprev) ++ prev = rb_entry_rq(rbprev); ++ ++ if (rbnext) ++ next = rb_entry_rq(rbnext); ++ else { ++ rbnext = rb_first(&bfqq->sort_list); ++ if (rbnext && rbnext != &last->rb_node) ++ next = rb_entry_rq(rbnext); ++ } ++ ++ return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last)); ++} ++ ++/* see the definition of bfq_async_charge_factor for details */ ++static unsigned long bfq_serv_to_charge(struct request *rq, ++ struct bfq_queue *bfqq) ++{ ++ return blk_rq_sectors(rq) * ++ (1 + ((!bfq_bfqq_sync(bfqq)) * (bfqq->wr_coeff == 1) * ++ bfq_async_charge_factor)); ++} ++ ++/** ++ * bfq_updated_next_req - update the queue after a new next_rq selection. ++ * @bfqd: the device data the queue belongs to. ++ * @bfqq: the queue to update. ++ * ++ * If the first request of a queue changes we make sure that the queue ++ * has enough budget to serve at least its first request (if the ++ * request has grown). We do this because if the queue has not enough ++ * budget for its first request, it has to go through two dispatch ++ * rounds to actually get it dispatched. ++ */ ++static void bfq_updated_next_req(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ struct request *next_rq = bfqq->next_rq; ++ unsigned long new_budget; ++ ++ if (!next_rq) ++ return; ++ ++ if (bfqq == bfqd->in_service_queue) ++ /* ++ * In order not to break guarantees, budgets cannot be ++ * changed after an entity has been selected. ++ */ ++ return; ++ ++ BUG_ON(entity->tree != &st->active); ++ BUG_ON(entity == entity->sched_data->in_service_entity); ++ ++ new_budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)); ++ if (entity->budget != new_budget) { ++ entity->budget = new_budget; ++ bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu", ++ new_budget); ++ bfq_activate_bfqq(bfqd, bfqq); ++ } ++} ++ ++static unsigned int bfq_wr_duration(struct bfq_data *bfqd) ++{ ++ u64 dur; ++ ++ if (bfqd->bfq_wr_max_time > 0) ++ return bfqd->bfq_wr_max_time; ++ ++ dur = bfqd->RT_prod; ++ do_div(dur, bfqd->peak_rate); ++ ++ return dur; ++} ++ ++/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */ ++static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_queue *item; ++ struct hlist_node *n; ++ ++ hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node) ++ hlist_del_init(&item->burst_list_node); ++ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); ++ bfqd->burst_size = 1; ++} ++ ++/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */ ++static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ /* Increment burst size to take into account also bfqq */ ++ bfqd->burst_size++; ++ ++ if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) { ++ struct bfq_queue *pos, *bfqq_item; ++ struct hlist_node *n; ++ ++ /* ++ * Enough queues have been activated shortly after each ++ * other to consider this burst as large. ++ */ ++ bfqd->large_burst = true; ++ ++ /* ++ * We can now mark all queues in the burst list as ++ * belonging to a large burst. ++ */ ++ hlist_for_each_entry(bfqq_item, &bfqd->burst_list, ++ burst_list_node) ++ bfq_mark_bfqq_in_large_burst(bfqq_item); ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ ++ /* ++ * From now on, and until the current burst finishes, any ++ * new queue being activated shortly after the last queue ++ * was inserted in the burst can be immediately marked as ++ * belonging to a large burst. So the burst list is not ++ * needed any more. Remove it. ++ */ ++ hlist_for_each_entry_safe(pos, n, &bfqd->burst_list, ++ burst_list_node) ++ hlist_del_init(&pos->burst_list_node); ++ } else /* burst not yet large: add bfqq to the burst list */ ++ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); ++} ++ ++/* ++ * If many queues happen to become active shortly after each other, then, ++ * to help the processes associated to these queues get their job done as ++ * soon as possible, it is usually better to not grant either weight-raising ++ * or device idling to these queues. In this comment we describe, firstly, ++ * the reasons why this fact holds, and, secondly, the next function, which ++ * implements the main steps needed to properly mark these queues so that ++ * they can then be treated in a different way. ++ * ++ * As for the terminology, we say that a queue becomes active, i.e., ++ * switches from idle to backlogged, either when it is created (as a ++ * consequence of the arrival of an I/O request), or, if already existing, ++ * when a new request for the queue arrives while the queue is idle. ++ * Bursts of activations, i.e., activations of different queues occurring ++ * shortly after each other, are typically caused by services or applications ++ * that spawn or reactivate many parallel threads/processes. Examples are ++ * systemd during boot or git grep. ++ * ++ * These services or applications benefit mostly from a high throughput: ++ * the quicker the requests of the activated queues are cumulatively served, ++ * the sooner the target job of these queues gets completed. As a consequence, ++ * weight-raising any of these queues, which also implies idling the device ++ * for it, is almost always counterproductive: in most cases it just lowers ++ * throughput. ++ * ++ * On the other hand, a burst of activations may be also caused by the start ++ * of an application that does not consist in a lot of parallel I/O-bound ++ * threads. In fact, with a complex application, the burst may be just a ++ * consequence of the fact that several processes need to be executed to ++ * start-up the application. To start an application as quickly as possible, ++ * the best thing to do is to privilege the I/O related to the application ++ * with respect to all other I/O. Therefore, the best strategy to start as ++ * quickly as possible an application that causes a burst of activations is ++ * to weight-raise all the queues activated during the burst. This is the ++ * exact opposite of the best strategy for the other type of bursts. ++ * ++ * In the end, to take the best action for each of the two cases, the two ++ * types of bursts need to be distinguished. Fortunately, this seems ++ * relatively easy to do, by looking at the sizes of the bursts. In ++ * particular, we found a threshold such that bursts with a larger size ++ * than that threshold are apparently caused only by services or commands ++ * such as systemd or git grep. For brevity, hereafter we call just 'large' ++ * these bursts. BFQ *does not* weight-raise queues whose activations occur ++ * in a large burst. In addition, for each of these queues BFQ performs or ++ * does not perform idling depending on which choice boosts the throughput ++ * most. The exact choice depends on the device and request pattern at ++ * hand. ++ * ++ * Turning back to the next function, it implements all the steps needed ++ * to detect the occurrence of a large burst and to properly mark all the ++ * queues belonging to it (so that they can then be treated in a different ++ * way). This goal is achieved by maintaining a special "burst list" that ++ * holds, temporarily, the queues that belong to the burst in progress. The ++ * list is then used to mark these queues as belonging to a large burst if ++ * the burst does become large. The main steps are the following. ++ * ++ * . when the very first queue is activated, the queue is inserted into the ++ * list (as it could be the first queue in a possible burst) ++ * ++ * . if the current burst has not yet become large, and a queue Q that does ++ * not yet belong to the burst is activated shortly after the last time ++ * at which a new queue entered the burst list, then the function appends ++ * Q to the burst list ++ * ++ * . if, as a consequence of the previous step, the burst size reaches ++ * the large-burst threshold, then ++ * ++ * . all the queues in the burst list are marked as belonging to a ++ * large burst ++ * ++ * . the burst list is deleted; in fact, the burst list already served ++ * its purpose (keeping temporarily track of the queues in a burst, ++ * so as to be able to mark them as belonging to a large burst in the ++ * previous sub-step), and now is not needed any more ++ * ++ * . the device enters a large-burst mode ++ * ++ * . if a queue Q that does not belong to the burst is activated while ++ * the device is in large-burst mode and shortly after the last time ++ * at which a queue either entered the burst list or was marked as ++ * belonging to the current large burst, then Q is immediately marked ++ * as belonging to a large burst. ++ * ++ * . if a queue Q that does not belong to the burst is activated a while ++ * later, i.e., not shortly after, than the last time at which a queue ++ * either entered the burst list or was marked as belonging to the ++ * current large burst, then the current burst is deemed as finished and: ++ * ++ * . the large-burst mode is reset if set ++ * ++ * . the burst list is emptied ++ * ++ * . Q is inserted in the burst list, as Q may be the first queue ++ * in a possible new burst (then the burst list contains just Q ++ * after this step). ++ */ ++static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ bool idle_for_long_time) ++{ ++ /* ++ * If bfqq happened to be activated in a burst, but has been idle ++ * for at least as long as an interactive queue, then we assume ++ * that, in the overall I/O initiated in the burst, the I/O ++ * associated to bfqq is finished. So bfqq does not need to be ++ * treated as a queue belonging to a burst anymore. Accordingly, ++ * we reset bfqq's in_large_burst flag if set, and remove bfqq ++ * from the burst list if it's there. We do not decrement instead ++ * burst_size, because the fact that bfqq does not need to belong ++ * to the burst list any more does not invalidate the fact that ++ * bfqq may have been activated during the current burst. ++ */ ++ if (idle_for_long_time) { ++ hlist_del_init(&bfqq->burst_list_node); ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ } ++ ++ /* ++ * If bfqq is already in the burst list or is part of a large ++ * burst, then there is nothing else to do. ++ */ ++ if (!hlist_unhashed(&bfqq->burst_list_node) || ++ bfq_bfqq_in_large_burst(bfqq)) ++ return; ++ ++ /* ++ * If bfqq's activation happens late enough, then the current ++ * burst is finished, and related data structures must be reset. ++ * ++ * In this respect, consider the special case where bfqq is the very ++ * first queue being activated. In this case, last_ins_in_burst is ++ * not yet significant when we get here. But it is easy to verify ++ * that, whether or not the following condition is true, bfqq will ++ * end up being inserted into the burst list. In particular the ++ * list will happen to contain only bfqq. And this is exactly what ++ * has to happen, as bfqq may be the first queue in a possible ++ * burst. ++ */ ++ if (time_is_before_jiffies(bfqd->last_ins_in_burst + ++ bfqd->bfq_burst_interval)) { ++ bfqd->large_burst = false; ++ bfq_reset_burst_list(bfqd, bfqq); ++ return; ++ } ++ ++ /* ++ * If we get here, then bfqq is being activated shortly after the ++ * last queue. So, if the current burst is also large, we can mark ++ * bfqq as belonging to this large burst immediately. ++ */ ++ if (bfqd->large_burst) { ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ return; ++ } ++ ++ /* ++ * If we get here, then a large-burst state has not yet been ++ * reached, but bfqq is being activated shortly after the last ++ * queue. Then we add bfqq to the burst. ++ */ ++ bfq_add_to_burst(bfqd, bfqq); ++} ++ ++static void bfq_add_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_data *bfqd = bfqq->bfqd; ++ struct request *next_rq, *prev; ++ unsigned long old_wr_coeff = bfqq->wr_coeff; ++ bool interactive = false; ++ ++ bfq_log_bfqq(bfqd, bfqq, "add_request %d", rq_is_sync(rq)); ++ bfqq->queued[rq_is_sync(rq)]++; ++ bfqd->queued++; ++ ++ elv_rb_add(&bfqq->sort_list, rq); ++ ++ /* ++ * Check if this request is a better next-serve candidate. ++ */ ++ prev = bfqq->next_rq; ++ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position); ++ BUG_ON(!next_rq); ++ bfqq->next_rq = next_rq; ++ ++ if (!bfq_bfqq_busy(bfqq)) { ++ bool soft_rt, in_burst, ++ idle_for_long_time = time_is_before_jiffies( ++ bfqq->budget_timeout + ++ bfqd->bfq_wr_min_idle_time); ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, ++ rq->cmd_flags); ++#endif ++ if (bfq_bfqq_sync(bfqq)) { ++ bool already_in_burst = ++ !hlist_unhashed(&bfqq->burst_list_node) || ++ bfq_bfqq_in_large_burst(bfqq); ++ bfq_handle_burst(bfqd, bfqq, idle_for_long_time); ++ /* ++ * If bfqq was not already in the current burst, ++ * then, at this point, bfqq either has been ++ * added to the current burst or has caused the ++ * current burst to terminate. In particular, in ++ * the second case, bfqq has become the first ++ * queue in a possible new burst. ++ * In both cases last_ins_in_burst needs to be ++ * moved forward. ++ */ ++ if (!already_in_burst) ++ bfqd->last_ins_in_burst = jiffies; ++ } ++ ++ in_burst = bfq_bfqq_in_large_burst(bfqq); ++ soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && ++ !in_burst && ++ time_is_before_jiffies(bfqq->soft_rt_next_start); ++ interactive = !in_burst && idle_for_long_time; ++ entity->budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)); ++ ++ if (!bfq_bfqq_IO_bound(bfqq)) { ++ if (time_before(jiffies, ++ RQ_BIC(rq)->ttime.last_end_request + ++ bfqd->bfq_slice_idle)) { ++ bfqq->requests_within_timer++; ++ if (bfqq->requests_within_timer >= ++ bfqd->bfq_requests_within_timer) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ } else ++ bfqq->requests_within_timer = 0; ++ } ++ ++ if (!bfqd->low_latency) ++ goto add_bfqq_busy; ++ ++ /* ++ * If the queue: ++ * - is not being boosted, ++ * - has been idle for enough time, ++ * - is not a sync queue or is linked to a bfq_io_cq (it is ++ * shared "for its nature" or it is not shared and its ++ * requests have not been redirected to a shared queue) ++ * start a weight-raising period. ++ */ ++ if (old_wr_coeff == 1 && (interactive || soft_rt) && ++ (!bfq_bfqq_sync(bfqq) || bfqq->bic)) { ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ if (interactive) ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ else ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais starting at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } else if (old_wr_coeff > 1) { ++ if (interactive) ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ else if (in_burst || ++ (bfqq->wr_cur_max_time == ++ bfqd->bfq_wr_rt_max_time && ++ !soft_rt)) { ++ bfqq->wr_coeff = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq-> ++ wr_cur_max_time)); ++ } else if (time_before( ++ bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time, ++ jiffies + ++ bfqd->bfq_wr_rt_max_time) && ++ soft_rt) { ++ /* ++ * ++ * The remaining weight-raising time is lower ++ * than bfqd->bfq_wr_rt_max_time, which means ++ * that the application is enjoying weight ++ * raising either because deemed soft-rt in ++ * the near past, or because deemed interactive ++ * a long ago. ++ * In both cases, resetting now the current ++ * remaining weight-raising time for the ++ * application to the weight-raising duration ++ * for soft rt applications would not cause any ++ * latency increase for the application (as the ++ * new duration would be higher than the ++ * remaining time). ++ * ++ * In addition, the application is now meeting ++ * the requirements for being deemed soft rt. ++ * In the end we can correctly and safely ++ * (re)charge the weight-raising duration for ++ * the application with the weight-raising ++ * duration for soft rt applications. ++ * ++ * In particular, doing this recharge now, i.e., ++ * before the weight-raising period for the ++ * application finishes, reduces the probability ++ * of the following negative scenario: ++ * 1) the weight of a soft rt application is ++ * raised at startup (as for any newly ++ * created application), ++ * 2) since the application is not interactive, ++ * at a certain time weight-raising is ++ * stopped for the application, ++ * 3) at that time the application happens to ++ * still have pending requests, and hence ++ * is destined to not have a chance to be ++ * deemed soft rt before these requests are ++ * completed (see the comments to the ++ * function bfq_bfqq_softrt_next_start() ++ * for details on soft rt detection), ++ * 4) these pending requests experience a high ++ * latency because the application is not ++ * weight-raised while they are pending. ++ */ ++ bfqq->last_wr_start_finish = jiffies; ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ } ++ } ++ if (old_wr_coeff != bfqq->wr_coeff) ++ entity->prio_changed = 1; ++add_bfqq_busy: ++ bfqq->last_idle_bklogged = jiffies; ++ bfqq->service_from_backlogged = 0; ++ bfq_clear_bfqq_softrt_update(bfqq); ++ bfq_add_bfqq_busy(bfqd, bfqq); ++ } else { ++ if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) && ++ time_is_before_jiffies( ++ bfqq->last_wr_start_finish + ++ bfqd->bfq_wr_min_inter_arr_async)) { ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ ++ bfqd->wr_busy_queues++; ++ entity->prio_changed = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "non-idle wrais starting at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ if (prev != bfqq->next_rq) ++ bfq_updated_next_req(bfqd, bfqq); ++ } ++ ++ if (bfqd->low_latency && ++ (old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive)) ++ bfqq->last_wr_start_finish = jiffies; ++} ++ ++static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd, ++ struct bio *bio) ++{ ++ struct task_struct *tsk = current; ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq; ++ ++ bic = bfq_bic_lookup(bfqd, tsk->io_context); ++ if (!bic) ++ return NULL; ++ ++ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio)); ++ if (bfqq) ++ return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio)); ++ ++ return NULL; ++} ++ ++static void bfq_activate_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ ++ bfqd->rq_in_driver++; ++ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); ++ bfq_log(bfqd, "activate_request: new bfqd->last_position %llu", ++ (long long unsigned)bfqd->last_position); ++} ++ ++static void bfq_deactivate_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ ++ BUG_ON(bfqd->rq_in_driver == 0); ++ bfqd->rq_in_driver--; ++} ++ ++static void bfq_remove_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ const int sync = rq_is_sync(rq); ++ ++ if (bfqq->next_rq == rq) { ++ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq); ++ bfq_updated_next_req(bfqd, bfqq); ++ } ++ ++ if (rq->queuelist.prev != &rq->queuelist) ++ list_del_init(&rq->queuelist); ++ BUG_ON(bfqq->queued[sync] == 0); ++ bfqq->queued[sync]--; ++ bfqd->queued--; ++ elv_rb_del(&bfqq->sort_list, rq); ++ ++ if (RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) ++ bfq_del_bfqq_busy(bfqd, bfqq, 1); ++ /* ++ * Remove queue from request-position tree as it is empty. ++ */ ++ if (bfqq->pos_root) { ++ rb_erase(&bfqq->pos_node, bfqq->pos_root); ++ bfqq->pos_root = NULL; ++ } ++ } ++ ++ if (rq->cmd_flags & REQ_META) { ++ BUG_ON(bfqq->meta_pending == 0); ++ bfqq->meta_pending--; ++ } ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags); ++#endif ++} ++ ++static int bfq_merge(struct request_queue *q, struct request **req, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct request *__rq; ++ ++ __rq = bfq_find_rq_fmerge(bfqd, bio); ++ if (__rq && elv_rq_merge_ok(__rq, bio)) { ++ *req = __rq; ++ return ELEVATOR_FRONT_MERGE; ++ } ++ ++ return ELEVATOR_NO_MERGE; ++} ++ ++static void bfq_merged_request(struct request_queue *q, struct request *req, ++ int type) ++{ ++ if (type == ELEVATOR_FRONT_MERGE && ++ rb_prev(&req->rb_node) && ++ blk_rq_pos(req) < ++ blk_rq_pos(container_of(rb_prev(&req->rb_node), ++ struct request, rb_node))) { ++ struct bfq_queue *bfqq = RQ_BFQQ(req); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ struct request *prev, *next_rq; ++ ++ /* Reposition request in its sort_list */ ++ elv_rb_del(&bfqq->sort_list, req); ++ elv_rb_add(&bfqq->sort_list, req); ++ /* Choose next request to be served for bfqq */ ++ prev = bfqq->next_rq; ++ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req, ++ bfqd->last_position); ++ BUG_ON(!next_rq); ++ bfqq->next_rq = next_rq; ++ } ++} ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++static void bfq_bio_merged(struct request_queue *q, struct request *req, ++ struct bio *bio) ++{ ++ bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_rw); ++} ++#endif ++ ++static void bfq_merged_requests(struct request_queue *q, struct request *rq, ++ struct request *next) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next); ++ ++ /* ++ * If next and rq belong to the same bfq_queue and next is older ++ * than rq, then reposition rq in the fifo (by substituting next ++ * with rq). Otherwise, if next and rq belong to different ++ * bfq_queues, never reposition rq: in fact, we would have to ++ * reposition it with respect to next's position in its own fifo, ++ * which would most certainly be too expensive with respect to ++ * the benefits. ++ */ ++ if (bfqq == next_bfqq && ++ !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && ++ time_before(next->fifo_time, rq->fifo_time)) { ++ list_del_init(&rq->queuelist); ++ list_replace_init(&next->queuelist, &rq->queuelist); ++ rq->fifo_time = next->fifo_time; ++ } ++ ++ if (bfqq->next_rq == next) ++ bfqq->next_rq = rq; ++ ++ bfq_remove_request(next); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags); ++#endif ++} ++ ++/* Must be called with bfqq != NULL */ ++static void bfq_bfqq_end_wr(struct bfq_queue *bfqq) ++{ ++ BUG_ON(!bfqq); ++ if (bfq_bfqq_busy(bfqq)) ++ bfqq->bfqd->wr_busy_queues--; ++ bfqq->wr_coeff = 1; ++ bfqq->wr_cur_max_time = 0; ++ /* Trigger a weight change on the next activation of the queue */ ++ bfqq->entity.prio_changed = 1; ++} ++ ++static void bfq_end_wr_async_queues(struct bfq_data *bfqd, ++ struct bfq_group *bfqg) ++{ ++ int i, j; ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < IOPRIO_BE_NR; j++) ++ if (bfqg->async_bfqq[i][j]) ++ bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]); ++ if (bfqg->async_idle_bfqq) ++ bfq_bfqq_end_wr(bfqg->async_idle_bfqq); ++} ++ ++static void bfq_end_wr(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ ++ spin_lock_irq(bfqd->queue->queue_lock); ++ ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) ++ bfq_bfqq_end_wr(bfqq); ++ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) ++ bfq_bfqq_end_wr(bfqq); ++ bfq_end_wr_async(bfqd); ++ ++ spin_unlock_irq(bfqd->queue->queue_lock); ++} ++ ++static int bfq_allow_merge(struct request_queue *q, struct request *rq, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_io_cq *bic; ++ ++ /* ++ * Disallow merge of a sync bio into an async request. ++ */ ++ if (bfq_bio_sync(bio) && !rq_is_sync(rq)) ++ return 0; ++ ++ /* ++ * Lookup the bfqq that this bio will be queued with. Allow ++ * merge only if rq is queued there. ++ * Queue lock is held here. ++ */ ++ bic = bfq_bic_lookup(bfqd, current->io_context); ++ if (!bic) ++ return 0; ++ ++ return bic_to_bfqq(bic, bfq_bio_sync(bio)) == RQ_BFQQ(rq); ++} ++ ++static void __bfq_set_in_service_queue(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ if (bfqq) { ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_avg_queue_size(bfqq_group(bfqq)); ++#endif ++ bfq_mark_bfqq_must_alloc(bfqq); ++ bfq_mark_bfqq_budget_new(bfqq); ++ bfq_clear_bfqq_fifo_expire(bfqq); ++ ++ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8; ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "set_in_service_queue, cur-budget = %d", ++ bfqq->entity.budget); ++ } ++ ++ bfqd->in_service_queue = bfqq; ++} ++ ++/* ++ * Get and set a new queue for service. ++ */ ++static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfq_get_next_queue(bfqd); ++ ++ __bfq_set_in_service_queue(bfqd, bfqq); ++ return bfqq; ++} ++ ++/* ++ * If enough samples have been computed, return the current max budget ++ * stored in bfqd, which is dynamically updated according to the ++ * estimated disk peak rate; otherwise return the default max budget ++ */ ++static int bfq_max_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < bfq_stats_min_budgets) ++ return bfq_default_max_budget; ++ else ++ return bfqd->bfq_max_budget; ++} ++ ++/* ++ * Return min budget, which is a fraction of the current or default ++ * max budget (trying with 1/32) ++ */ ++static int bfq_min_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < bfq_stats_min_budgets) ++ return bfq_default_max_budget / 32; ++ else ++ return bfqd->bfq_max_budget / 32; ++} ++ ++static void bfq_arm_slice_timer(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ struct bfq_io_cq *bic; ++ unsigned long sl; ++ ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ /* Processes have exited, don't wait. */ ++ bic = bfqd->in_service_bic; ++ if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0) ++ return; ++ ++ bfq_mark_bfqq_wait_request(bfqq); ++ ++ /* ++ * We don't want to idle for seeks, but we do want to allow ++ * fair distribution of slice time for a process doing back-to-back ++ * seeks. So allow a little bit of time for him to submit a new rq. ++ * ++ * To prevent processes with (partly) seeky workloads from ++ * being too ill-treated, grant them a small fraction of the ++ * assigned budget before reducing the waiting time to ++ * BFQ_MIN_TT. This happened to help reduce latency. ++ */ ++ sl = bfqd->bfq_slice_idle; ++ /* ++ * Unless the queue is being weight-raised or the scenario is ++ * asymmetric, grant only minimum idle time if the queue either ++ * has been seeky for long enough or has already proved to be ++ * constantly seeky. ++ */ ++ if (bfq_sample_valid(bfqq->seek_samples) && ++ ((BFQQ_SEEKY(bfqq) && bfqq->entity.service > ++ bfq_max_budget(bfqq->bfqd) / 8) || ++ bfq_bfqq_constantly_seeky(bfqq)) && bfqq->wr_coeff == 1 && ++ bfq_symmetric_scenario(bfqd)) ++ sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT)); ++ else if (bfqq->wr_coeff > 1) ++ sl = sl * 3; ++ bfqd->last_idling_start = ktime_get(); ++ mod_timer(&bfqd->idle_slice_timer, jiffies + sl); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_set_start_idle_time(bfqq_group(bfqq)); ++#endif ++ bfq_log(bfqd, "arm idle: %u/%u ms", ++ jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle)); ++} ++ ++/* ++ * Set the maximum time for the in-service queue to consume its ++ * budget. This prevents seeky processes from lowering the disk ++ * throughput (always guaranteed with a time slice scheme as in CFQ). ++ */ ++static void bfq_set_budget_timeout(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ unsigned int timeout_coeff; ++ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time) ++ timeout_coeff = 1; ++ else ++ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight; ++ ++ bfqd->last_budget_start = ktime_get(); ++ ++ bfq_clear_bfqq_budget_new(bfqq); ++ bfqq->budget_timeout = jiffies + ++ bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * timeout_coeff; ++ ++ bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u", ++ jiffies_to_msecs(bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * ++ timeout_coeff)); ++} ++ ++/* ++ * Move request from internal lists to the request queue dispatch list. ++ */ ++static void bfq_dispatch_insert(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ /* ++ * For consistency, the next instruction should have been executed ++ * after removing the request from the queue and dispatching it. ++ * We execute instead this instruction before bfq_remove_request() ++ * (and hence introduce a temporary inconsistency), for efficiency. ++ * In fact, in a forced_dispatch, this prevents two counters related ++ * to bfqq->dispatched to risk to be uselessly decremented if bfqq ++ * is not in service, and then to be incremented again after ++ * incrementing bfqq->dispatched. ++ */ ++ bfqq->dispatched++; ++ bfq_remove_request(rq); ++ elv_dispatch_sort(q, rq); ++ ++ if (bfq_bfqq_sync(bfqq)) ++ bfqd->sync_flight++; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_dispatch(bfqq_group(bfqq), blk_rq_bytes(rq), ++ rq->cmd_flags); ++#endif ++} ++ ++/* ++ * Return expired entry, or NULL to just start from scratch in rbtree. ++ */ ++static struct request *bfq_check_fifo(struct bfq_queue *bfqq) ++{ ++ struct request *rq = NULL; ++ ++ if (bfq_bfqq_fifo_expire(bfqq)) ++ return NULL; ++ ++ bfq_mark_bfqq_fifo_expire(bfqq); ++ ++ if (list_empty(&bfqq->fifo)) ++ return NULL; ++ ++ rq = rq_entry_fifo(bfqq->fifo.next); ++ ++ if (time_before(jiffies, rq->fifo_time)) ++ return NULL; ++ ++ return rq; ++} ++ ++static int bfq_bfqq_budget_left(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ return entity->budget - entity->service; ++} ++ ++static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ __bfq_bfqd_reset_in_service(bfqd); ++ ++ if (RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ /* ++ * Overloading budget_timeout field to store the time ++ * at which the queue remains with no backlog; used by ++ * the weight-raising mechanism. ++ */ ++ bfqq->budget_timeout = jiffies; ++ bfq_del_bfqq_busy(bfqd, bfqq, 1); ++ } else ++ bfq_activate_bfqq(bfqd, bfqq); ++} ++ ++/** ++ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior. ++ * @bfqd: device data. ++ * @bfqq: queue to update. ++ * @reason: reason for expiration. ++ * ++ * Handle the feedback on @bfqq budget at queue expiration. ++ * See the body for detailed comments. ++ */ ++static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ enum bfqq_expiration reason) ++{ ++ struct request *next_rq; ++ int budget, min_budget; ++ ++ budget = bfqq->max_budget; ++ min_budget = bfq_min_budget(bfqd); ++ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d", ++ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq)); ++ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d", ++ budget, bfq_min_budget(bfqd)); ++ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d", ++ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue)); ++ ++ if (bfq_bfqq_sync(bfqq)) { ++ switch (reason) { ++ /* ++ * Caveat: in all the following cases we trade latency ++ * for throughput. ++ */ ++ case BFQ_BFQQ_TOO_IDLE: ++ /* ++ * This is the only case where we may reduce ++ * the budget: if there is no request of the ++ * process still waiting for completion, then ++ * we assume (tentatively) that the timer has ++ * expired because the batch of requests of ++ * the process could have been served with a ++ * smaller budget. Hence, betting that ++ * process will behave in the same way when it ++ * becomes backlogged again, we reduce its ++ * next budget. As long as we guess right, ++ * this budget cut reduces the latency ++ * experienced by the process. ++ * ++ * However, if there are still outstanding ++ * requests, then the process may have not yet ++ * issued its next request just because it is ++ * still waiting for the completion of some of ++ * the still outstanding ones. So in this ++ * subcase we do not reduce its budget, on the ++ * contrary we increase it to possibly boost ++ * the throughput, as discussed in the ++ * comments to the BUDGET_TIMEOUT case. ++ */ ++ if (bfqq->dispatched > 0) /* still outstanding reqs */ ++ budget = min(budget * 2, bfqd->bfq_max_budget); ++ else { ++ if (budget > 5 * min_budget) ++ budget -= 4 * min_budget; ++ else ++ budget = min_budget; ++ } ++ break; ++ case BFQ_BFQQ_BUDGET_TIMEOUT: ++ /* ++ * We double the budget here because: 1) it ++ * gives the chance to boost the throughput if ++ * this is not a seeky process (which may have ++ * bumped into this timeout because of, e.g., ++ * ZBR), 2) together with charge_full_budget ++ * it helps give seeky processes higher ++ * timestamps, and hence be served less ++ * frequently. ++ */ ++ budget = min(budget * 2, bfqd->bfq_max_budget); ++ break; ++ case BFQ_BFQQ_BUDGET_EXHAUSTED: ++ /* ++ * The process still has backlog, and did not ++ * let either the budget timeout or the disk ++ * idling timeout expire. Hence it is not ++ * seeky, has a short thinktime and may be ++ * happy with a higher budget too. So ++ * definitely increase the budget of this good ++ * candidate to boost the disk throughput. ++ */ ++ budget = min(budget * 4, bfqd->bfq_max_budget); ++ break; ++ case BFQ_BFQQ_NO_MORE_REQUESTS: ++ /* ++ * Leave the budget unchanged. ++ */ ++ default: ++ return; ++ } ++ } else ++ /* ++ * Async queues get always the maximum possible budget ++ * (their ability to dispatch is limited by ++ * @bfqd->bfq_max_budget_async_rq). ++ */ ++ budget = bfqd->bfq_max_budget; ++ ++ bfqq->max_budget = budget; ++ ++ if (bfqd->budgets_assigned >= bfq_stats_min_budgets && ++ !bfqd->bfq_user_max_budget) ++ bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget); ++ ++ /* ++ * Make sure that we have enough budget for the next request. ++ * Since the finish time of the bfqq must be kept in sync with ++ * the budget, be sure to call __bfq_bfqq_expire() after the ++ * update. ++ */ ++ next_rq = bfqq->next_rq; ++ if (next_rq) ++ bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)); ++ else ++ bfqq->entity.budget = bfqq->max_budget; ++ ++ bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d", ++ next_rq ? blk_rq_sectors(next_rq) : 0, ++ bfqq->entity.budget); ++} ++ ++static unsigned long bfq_calc_max_budget(u64 peak_rate, u64 timeout) ++{ ++ unsigned long max_budget; ++ ++ /* ++ * The max_budget calculated when autotuning is equal to the ++ * amount of sectors transfered in timeout_sync at the ++ * estimated peak rate. ++ */ ++ max_budget = (unsigned long)(peak_rate * 1000 * ++ timeout >> BFQ_RATE_SHIFT); ++ ++ return max_budget; ++} ++ ++/* ++ * In addition to updating the peak rate, checks whether the process ++ * is "slow", and returns 1 if so. This slow flag is used, in addition ++ * to the budget timeout, to reduce the amount of service provided to ++ * seeky processes, and hence reduce their chances to lower the ++ * throughput. See the code for more details. ++ */ ++static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ bool compensate, enum bfqq_expiration reason) ++{ ++ u64 bw, usecs, expected, timeout; ++ ktime_t delta; ++ int update = 0; ++ ++ if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq)) ++ return false; ++ ++ if (compensate) ++ delta = bfqd->last_idling_start; ++ else ++ delta = ktime_get(); ++ delta = ktime_sub(delta, bfqd->last_budget_start); ++ usecs = ktime_to_us(delta); ++ ++ /* Don't trust short/unrealistic values. */ ++ if (usecs < 100 || usecs >= LONG_MAX) ++ return false; ++ ++ /* ++ * Calculate the bandwidth for the last slice. We use a 64 bit ++ * value to store the peak rate, in sectors per usec in fixed ++ * point math. We do so to have enough precision in the estimate ++ * and to avoid overflows. ++ */ ++ bw = (u64)bfqq->entity.service << BFQ_RATE_SHIFT; ++ do_div(bw, (unsigned long)usecs); ++ ++ timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]); ++ ++ /* ++ * Use only long (> 20ms) intervals to filter out spikes for ++ * the peak rate estimation. ++ */ ++ if (usecs > 20000) { ++ if (bw > bfqd->peak_rate || ++ (!BFQQ_SEEKY(bfqq) && ++ reason == BFQ_BFQQ_BUDGET_TIMEOUT)) { ++ bfq_log(bfqd, "measured bw =%llu", bw); ++ /* ++ * To smooth oscillations use a low-pass filter with ++ * alpha=7/8, i.e., ++ * new_rate = (7/8) * old_rate + (1/8) * bw ++ */ ++ do_div(bw, 8); ++ if (bw == 0) ++ return 0; ++ bfqd->peak_rate *= 7; ++ do_div(bfqd->peak_rate, 8); ++ bfqd->peak_rate += bw; ++ update = 1; ++ bfq_log(bfqd, "new peak_rate=%llu", bfqd->peak_rate); ++ } ++ ++ update |= bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES - 1; ++ ++ if (bfqd->peak_rate_samples < BFQ_PEAK_RATE_SAMPLES) ++ bfqd->peak_rate_samples++; ++ ++ if (bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES && ++ update) { ++ int dev_type = blk_queue_nonrot(bfqd->queue); ++ if (bfqd->bfq_user_max_budget == 0) { ++ bfqd->bfq_max_budget = ++ bfq_calc_max_budget(bfqd->peak_rate, ++ timeout); ++ bfq_log(bfqd, "new max_budget=%d", ++ bfqd->bfq_max_budget); ++ } ++ if (bfqd->device_speed == BFQ_BFQD_FAST && ++ bfqd->peak_rate < device_speed_thresh[dev_type]) { ++ bfqd->device_speed = BFQ_BFQD_SLOW; ++ bfqd->RT_prod = R_slow[dev_type] * ++ T_slow[dev_type]; ++ } else if (bfqd->device_speed == BFQ_BFQD_SLOW && ++ bfqd->peak_rate > device_speed_thresh[dev_type]) { ++ bfqd->device_speed = BFQ_BFQD_FAST; ++ bfqd->RT_prod = R_fast[dev_type] * ++ T_fast[dev_type]; ++ } ++ } ++ } ++ ++ /* ++ * If the process has been served for a too short time ++ * interval to let its possible sequential accesses prevail on ++ * the initial seek time needed to move the disk head on the ++ * first sector it requested, then give the process a chance ++ * and for the moment return false. ++ */ ++ if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8) ++ return false; ++ ++ /* ++ * A process is considered ``slow'' (i.e., seeky, so that we ++ * cannot treat it fairly in the service domain, as it would ++ * slow down too much the other processes) if, when a slice ++ * ends for whatever reason, it has received service at a ++ * rate that would not be high enough to complete the budget ++ * before the budget timeout expiration. ++ */ ++ expected = bw * 1000 * timeout >> BFQ_RATE_SHIFT; ++ ++ /* ++ * Caveat: processes doing IO in the slower disk zones will ++ * tend to be slow(er) even if not seeky. And the estimated ++ * peak rate will actually be an average over the disk ++ * surface. Hence, to not be too harsh with unlucky processes, ++ * we keep a budget/3 margin of safety before declaring a ++ * process slow. ++ */ ++ return expected > (4 * bfqq->entity.budget) / 3; ++} ++ ++/* ++ * To be deemed as soft real-time, an application must meet two ++ * requirements. First, the application must not require an average ++ * bandwidth higher than the approximate bandwidth required to playback or ++ * record a compressed high-definition video. ++ * The next function is invoked on the completion of the last request of a ++ * batch, to compute the next-start time instant, soft_rt_next_start, such ++ * that, if the next request of the application does not arrive before ++ * soft_rt_next_start, then the above requirement on the bandwidth is met. ++ * ++ * The second requirement is that the request pattern of the application is ++ * isochronous, i.e., that, after issuing a request or a batch of requests, ++ * the application stops issuing new requests until all its pending requests ++ * have been completed. After that, the application may issue a new batch, ++ * and so on. ++ * For this reason the next function is invoked to compute ++ * soft_rt_next_start only for applications that meet this requirement, ++ * whereas soft_rt_next_start is set to infinity for applications that do ++ * not. ++ * ++ * Unfortunately, even a greedy application may happen to behave in an ++ * isochronous way if the CPU load is high. In fact, the application may ++ * stop issuing requests while the CPUs are busy serving other processes, ++ * then restart, then stop again for a while, and so on. In addition, if ++ * the disk achieves a low enough throughput with the request pattern ++ * issued by the application (e.g., because the request pattern is random ++ * and/or the device is slow), then the application may meet the above ++ * bandwidth requirement too. To prevent such a greedy application to be ++ * deemed as soft real-time, a further rule is used in the computation of ++ * soft_rt_next_start: soft_rt_next_start must be higher than the current ++ * time plus the maximum time for which the arrival of a request is waited ++ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle. ++ * This filters out greedy applications, as the latter issue instead their ++ * next request as soon as possible after the last one has been completed ++ * (in contrast, when a batch of requests is completed, a soft real-time ++ * application spends some time processing data). ++ * ++ * Unfortunately, the last filter may easily generate false positives if ++ * only bfqd->bfq_slice_idle is used as a reference time interval and one ++ * or both the following cases occur: ++ * 1) HZ is so low that the duration of a jiffy is comparable to or higher ++ * than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with ++ * HZ=100. ++ * 2) jiffies, instead of increasing at a constant rate, may stop increasing ++ * for a while, then suddenly 'jump' by several units to recover the lost ++ * increments. This seems to happen, e.g., inside virtual machines. ++ * To address this issue, we do not use as a reference time interval just ++ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In ++ * particular we add the minimum number of jiffies for which the filter ++ * seems to be quite precise also in embedded systems and KVM/QEMU virtual ++ * machines. ++ */ ++static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ return max(bfqq->last_idle_bklogged + ++ HZ * bfqq->service_from_backlogged / ++ bfqd->bfq_wr_max_softrt_rate, ++ jiffies + bfqq->bfqd->bfq_slice_idle + 4); ++} ++ ++/* ++ * Return the largest-possible time instant such that, for as long as possible, ++ * the current time will be lower than this time instant according to the macro ++ * time_is_before_jiffies(). ++ */ ++static unsigned long bfq_infinity_from_now(unsigned long now) ++{ ++ return now + ULONG_MAX / 2; ++} ++ ++/** ++ * bfq_bfqq_expire - expire a queue. ++ * @bfqd: device owning the queue. ++ * @bfqq: the queue to expire. ++ * @compensate: if true, compensate for the time spent idling. ++ * @reason: the reason causing the expiration. ++ * ++ * ++ * If the process associated to the queue is slow (i.e., seeky), or in ++ * case of budget timeout, or, finally, if it is async, we ++ * artificially charge it an entire budget (independently of the ++ * actual service it received). As a consequence, the queue will get ++ * higher timestamps than the correct ones upon reactivation, and ++ * hence it will be rescheduled as if it had received more service ++ * than what it actually received. In the end, this class of processes ++ * will receive less service in proportion to how slowly they consume ++ * their budgets (and hence how seriously they tend to lower the ++ * throughput). ++ * ++ * In contrast, when a queue expires because it has been idling for ++ * too much or because it exhausted its budget, we do not touch the ++ * amount of service it has received. Hence when the queue will be ++ * reactivated and its timestamps updated, the latter will be in sync ++ * with the actual service received by the queue until expiration. ++ * ++ * Charging a full budget to the first type of queues and the exact ++ * service to the others has the effect of using the WF2Q+ policy to ++ * schedule the former on a timeslice basis, without violating the ++ * service domain guarantees of the latter. ++ */ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool compensate, ++ enum bfqq_expiration reason) ++{ ++ bool slow; ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ /* ++ * Update disk peak rate for autotuning and check whether the ++ * process is slow (see bfq_update_peak_rate). ++ */ ++ slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason); ++ ++ /* ++ * As above explained, 'punish' slow (i.e., seeky), timed-out ++ * and async queues, to favor sequential sync workloads. ++ * ++ * Processes doing I/O in the slower disk zones will tend to be ++ * slow(er) even if not seeky. Hence, since the estimated peak ++ * rate is actually an average over the disk surface, these ++ * processes may timeout just for bad luck. To avoid punishing ++ * them we do not charge a full budget to a process that ++ * succeeded in consuming at least 2/3 of its budget. ++ */ ++ if (slow || (reason == BFQ_BFQQ_BUDGET_TIMEOUT && ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3)) ++ bfq_bfqq_charge_full_budget(bfqq); ++ ++ bfqq->service_from_backlogged += bfqq->entity.service; ++ ++ if (BFQQ_SEEKY(bfqq) && reason == BFQ_BFQQ_BUDGET_TIMEOUT && ++ !bfq_bfqq_constantly_seeky(bfqq)) { ++ bfq_mark_bfqq_constantly_seeky(bfqq); ++ if (!blk_queue_nonrot(bfqd->queue)) ++ bfqd->const_seeky_busy_in_flight_queues++; ++ } ++ ++ if (reason == BFQ_BFQQ_TOO_IDLE && ++ bfqq->entity.service <= 2 * bfqq->entity.budget / 10 ) ++ bfq_clear_bfqq_IO_bound(bfqq); ++ ++ if (bfqd->low_latency && bfqq->wr_coeff == 1) ++ bfqq->last_wr_start_finish = jiffies; ++ ++ if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 && ++ RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ /* ++ * If we get here, and there are no outstanding requests, ++ * then the request pattern is isochronous (see the comments ++ * to the function bfq_bfqq_softrt_next_start()). Hence we ++ * can compute soft_rt_next_start. If, instead, the queue ++ * still has outstanding requests, then we have to wait ++ * for the completion of all the outstanding requests to ++ * discover whether the request pattern is actually ++ * isochronous. ++ */ ++ if (bfqq->dispatched == 0) ++ bfqq->soft_rt_next_start = ++ bfq_bfqq_softrt_next_start(bfqd, bfqq); ++ else { ++ /* ++ * The application is still waiting for the ++ * completion of one or more requests: ++ * prevent it from possibly being incorrectly ++ * deemed as soft real-time by setting its ++ * soft_rt_next_start to infinity. In fact, ++ * without this assignment, the application ++ * would be incorrectly deemed as soft ++ * real-time if: ++ * 1) it issued a new request before the ++ * completion of all its in-flight ++ * requests, and ++ * 2) at that time, its soft_rt_next_start ++ * happened to be in the past. ++ */ ++ bfqq->soft_rt_next_start = ++ bfq_infinity_from_now(jiffies); ++ /* ++ * Schedule an update of soft_rt_next_start to when ++ * the task may be discovered to be isochronous. ++ */ ++ bfq_mark_bfqq_softrt_update(bfqq); ++ } ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "expire (%d, slow %d, num_disp %d, idle_win %d)", reason, ++ slow, bfqq->dispatched, bfq_bfqq_idle_window(bfqq)); ++ ++ /* ++ * Increase, decrease or leave budget unchanged according to ++ * reason. ++ */ ++ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason); ++ __bfq_bfqq_expire(bfqd, bfqq); ++} ++ ++/* ++ * Budget timeout is not implemented through a dedicated timer, but ++ * just checked on request arrivals and completions, as well as on ++ * idle timer expirations. ++ */ ++static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) ++{ ++ if (bfq_bfqq_budget_new(bfqq) || ++ time_before(jiffies, bfqq->budget_timeout)) ++ return false; ++ return true; ++} ++ ++/* ++ * If we expire a queue that is waiting for the arrival of a new ++ * request, we may prevent the fictitious timestamp back-shifting that ++ * allows the guarantees of the queue to be preserved (see [1] for ++ * this tricky aspect). Hence we return true only if this condition ++ * does not hold, or if the queue is slow enough to deserve only to be ++ * kicked off for preserving a high throughput. ++*/ ++static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "may_budget_timeout: wait_request %d left %d timeout %d", ++ bfq_bfqq_wait_request(bfqq), ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3, ++ bfq_bfqq_budget_timeout(bfqq)); ++ ++ return (!bfq_bfqq_wait_request(bfqq) || ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3) ++ && ++ bfq_bfqq_budget_timeout(bfqq); ++} ++ ++/* ++ * For a queue that becomes empty, device idling is allowed only if ++ * this function returns true for that queue. As a consequence, since ++ * device idling plays a critical role for both throughput boosting ++ * and service guarantees, the return value of this function plays a ++ * critical role as well. ++ * ++ * In a nutshell, this function returns true only if idling is ++ * beneficial for throughput or, even if detrimental for throughput, ++ * idling is however necessary to preserve service guarantees (low ++ * latency, desired throughput distribution, ...). In particular, on ++ * NCQ-capable devices, this function tries to return false, so as to ++ * help keep the drives' internal queues full, whenever this helps the ++ * device boost the throughput without causing any service-guarantee ++ * issue. ++ * ++ * In more detail, the return value of this function is obtained by, ++ * first, computing a number of boolean variables that take into ++ * account throughput and service-guarantee issues, and, then, ++ * combining these variables in a logical expression. Most of the ++ * issues taken into account are not trivial. We discuss these issues ++ * while introducing the variables. ++ */ ++static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++ bool idling_boosts_thr, idling_boosts_thr_without_issues, ++ all_queues_seeky, on_hdd_and_not_all_queues_seeky, ++ idling_needed_for_service_guarantees, ++ asymmetric_scenario; ++ ++ /* ++ * The next variable takes into account the cases where idling ++ * boosts the throughput. ++ * ++ * The value of the variable is computed considering, first, that ++ * idling is virtually always beneficial for the throughput if: ++ * (a) the device is not NCQ-capable, or ++ * (b) regardless of the presence of NCQ, the device is rotational ++ * and the request pattern for bfqq is I/O-bound and sequential. ++ * ++ * Secondly, and in contrast to the above item (b), idling an ++ * NCQ-capable flash-based device would not boost the ++ * throughput even with sequential I/O; rather it would lower ++ * the throughput in proportion to how fast the device ++ * is. Accordingly, the next variable is true if any of the ++ * above conditions (a) and (b) is true, and, in particular, ++ * happens to be false if bfqd is an NCQ-capable flash-based ++ * device. ++ */ ++ idling_boosts_thr = !bfqd->hw_tag || ++ (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) && ++ bfq_bfqq_idle_window(bfqq)) ; ++ ++ /* ++ * The value of the next variable, ++ * idling_boosts_thr_without_issues, is equal to that of ++ * idling_boosts_thr, unless a special case holds. In this ++ * special case, described below, idling may cause problems to ++ * weight-raised queues. ++ * ++ * When the request pool is saturated (e.g., in the presence ++ * of write hogs), if the processes associated with ++ * non-weight-raised queues ask for requests at a lower rate, ++ * then processes associated with weight-raised queues have a ++ * higher probability to get a request from the pool ++ * immediately (or at least soon) when they need one. Thus ++ * they have a higher probability to actually get a fraction ++ * of the device throughput proportional to their high ++ * weight. This is especially true with NCQ-capable drives, ++ * which enqueue several requests in advance, and further ++ * reorder internally-queued requests. ++ * ++ * For this reason, we force to false the value of ++ * idling_boosts_thr_without_issues if there are weight-raised ++ * busy queues. In this case, and if bfqq is not weight-raised, ++ * this guarantees that the device is not idled for bfqq (if, ++ * instead, bfqq is weight-raised, then idling will be ++ * guaranteed by another variable, see below). Combined with ++ * the timestamping rules of BFQ (see [1] for details), this ++ * behavior causes bfqq, and hence any sync non-weight-raised ++ * queue, to get a lower number of requests served, and thus ++ * to ask for a lower number of requests from the request ++ * pool, before the busy weight-raised queues get served ++ * again. This often mitigates starvation problems in the ++ * presence of heavy write workloads and NCQ, thereby ++ * guaranteeing a higher application and system responsiveness ++ * in these hostile scenarios. ++ */ ++ idling_boosts_thr_without_issues = idling_boosts_thr && ++ bfqd->wr_busy_queues == 0; ++ ++ /* ++ * There are then two cases where idling must be performed not ++ * for throughput concerns, but to preserve service ++ * guarantees. In the description of these cases, we say, for ++ * short, that a queue is sequential/random if the process ++ * associated to the queue issues sequential/random requests ++ * (in the second case the queue may be tagged as seeky or ++ * even constantly_seeky). ++ * ++ * To introduce the first case, we note that, since ++ * bfq_bfqq_idle_window(bfqq) is false if the device is ++ * NCQ-capable and bfqq is random (see ++ * bfq_update_idle_window()), then, from the above two ++ * assignments it follows that ++ * idling_boosts_thr_without_issues is false if the device is ++ * NCQ-capable and bfqq is random. Therefore, for this case, ++ * device idling would never be allowed if we used just ++ * idling_boosts_thr_without_issues to decide whether to allow ++ * it. And, beneficially, this would imply that throughput ++ * would always be boosted also with random I/O on NCQ-capable ++ * HDDs. ++ * ++ * But we must be careful on this point, to avoid an unfair ++ * treatment for bfqq. In fact, because of the same above ++ * assignments, idling_boosts_thr_without_issues is, on the ++ * other hand, true if 1) the device is an HDD and bfqq is ++ * sequential, and 2) there are no busy weight-raised ++ * queues. As a consequence, if we used just ++ * idling_boosts_thr_without_issues to decide whether to idle ++ * the device, then with an HDD we might easily bump into a ++ * scenario where queues that are sequential and I/O-bound ++ * would enjoy idling, whereas random queues would not. The ++ * latter might then get a low share of the device throughput, ++ * simply because the former would get many requests served ++ * after being set as in service, while the latter would not. ++ * ++ * To address this issue, we start by setting to true a ++ * sentinel variable, on_hdd_and_not_all_queues_seeky, if the ++ * device is rotational and not all queues with pending or ++ * in-flight requests are constantly seeky (i.e., there are ++ * active sequential queues, and bfqq might then be mistreated ++ * if it does not enjoy idling because it is random). ++ */ ++ all_queues_seeky = bfq_bfqq_constantly_seeky(bfqq) && ++ bfqd->busy_in_flight_queues == ++ bfqd->const_seeky_busy_in_flight_queues; ++ ++ on_hdd_and_not_all_queues_seeky = ++ !blk_queue_nonrot(bfqd->queue) && !all_queues_seeky; ++ ++ /* ++ * To introduce the second case where idling needs to be ++ * performed to preserve service guarantees, we can note that ++ * allowing the drive to enqueue more than one request at a ++ * time, and hence delegating de facto final scheduling ++ * decisions to the drive's internal scheduler, causes loss of ++ * control on the actual request service order. In particular, ++ * the critical situation is when requests from different ++ * processes happens to be present, at the same time, in the ++ * internal queue(s) of the drive. In such a situation, the ++ * drive, by deciding the service order of the ++ * internally-queued requests, does determine also the actual ++ * throughput distribution among these processes. But the ++ * drive typically has no notion or concern about per-process ++ * throughput distribution, and makes its decisions only on a ++ * per-request basis. Therefore, the service distribution ++ * enforced by the drive's internal scheduler is likely to ++ * coincide with the desired device-throughput distribution ++ * only in a completely symmetric scenario where: ++ * (i) each of these processes must get the same throughput as ++ * the others; ++ * (ii) all these processes have the same I/O pattern ++ (either sequential or random). ++ * In fact, in such a scenario, the drive will tend to treat ++ * the requests of each of these processes in about the same ++ * way as the requests of the others, and thus to provide ++ * each of these processes with about the same throughput ++ * (which is exactly the desired throughput distribution). In ++ * contrast, in any asymmetric scenario, device idling is ++ * certainly needed to guarantee that bfqq receives its ++ * assigned fraction of the device throughput (see [1] for ++ * details). ++ * ++ * We address this issue by controlling, actually, only the ++ * symmetry sub-condition (i), i.e., provided that ++ * sub-condition (i) holds, idling is not performed, ++ * regardless of whether sub-condition (ii) holds. In other ++ * words, only if sub-condition (i) holds, then idling is ++ * allowed, and the device tends to be prevented from queueing ++ * many requests, possibly of several processes. The reason ++ * for not controlling also sub-condition (ii) is that, first, ++ * in the case of an HDD, the asymmetry in terms of types of ++ * I/O patterns is already taken in to account in the above ++ * sentinel variable ++ * on_hdd_and_not_all_queues_seeky. Secondly, in the case of a ++ * flash-based device, we prefer however to privilege ++ * throughput (and idling lowers throughput for this type of ++ * devices), for the following reasons: ++ * 1) differently from HDDs, the service time of random ++ * requests is not orders of magnitudes lower than the service ++ * time of sequential requests; thus, even if processes doing ++ * sequential I/O get a preferential treatment with respect to ++ * others doing random I/O, the consequences are not as ++ * dramatic as with HDDs; ++ * 2) if a process doing random I/O does need strong ++ * throughput guarantees, it is hopefully already being ++ * weight-raised, or the user is likely to have assigned it a ++ * higher weight than the other processes (and thus ++ * sub-condition (i) is likely to be false, which triggers ++ * idling). ++ * ++ * According to the above considerations, the next variable is ++ * true (only) if sub-condition (i) holds. To compute the ++ * value of this variable, we not only use the return value of ++ * the function bfq_symmetric_scenario(), but also check ++ * whether bfqq is being weight-raised, because ++ * bfq_symmetric_scenario() does not take into account also ++ * weight-raised queues (see comments to ++ * bfq_weights_tree_add()). ++ * ++ * As a side note, it is worth considering that the above ++ * device-idling countermeasures may however fail in the ++ * following unlucky scenario: if idling is (correctly) ++ * disabled in a time period during which all symmetry ++ * sub-conditions hold, and hence the device is allowed to ++ * enqueue many requests, but at some later point in time some ++ * sub-condition stops to hold, then it may become impossible ++ * to let requests be served in the desired order until all ++ * the requests already queued in the device have been served. ++ */ ++ asymmetric_scenario = bfqq->wr_coeff > 1 || ++ !bfq_symmetric_scenario(bfqd); ++ ++ /* ++ * Finally, there is a case where maximizing throughput is the ++ * best choice even if it may cause unfairness toward ++ * bfqq. Such a case is when bfqq became active in a burst of ++ * queue activations. Queues that became active during a large ++ * burst benefit only from throughput, as discussed in the ++ * comments to bfq_handle_burst. Thus, if bfqq became active ++ * in a burst and not idling the device maximizes throughput, ++ * then the device must no be idled, because not idling the ++ * device provides bfqq and all other queues in the burst with ++ * maximum benefit. Combining this and the two cases above, we ++ * can now establish when idling is actually needed to ++ * preserve service guarantees. ++ */ ++ idling_needed_for_service_guarantees = ++ (on_hdd_and_not_all_queues_seeky || asymmetric_scenario) && ++ !bfq_bfqq_in_large_burst(bfqq); ++ ++ /* ++ * We have now all the components we need to compute the return ++ * value of the function, which is true only if both the following ++ * conditions hold: ++ * 1) bfqq is sync, because idling make sense only for sync queues; ++ * 2) idling either boosts the throughput (without issues), or ++ * is necessary to preserve service guarantees. ++ */ ++ return bfq_bfqq_sync(bfqq) && ++ (idling_boosts_thr_without_issues || ++ idling_needed_for_service_guarantees); ++} ++ ++/* ++ * If the in-service queue is empty but the function bfq_bfqq_may_idle ++ * returns true, then: ++ * 1) the queue must remain in service and cannot be expired, and ++ * 2) the device must be idled to wait for the possible arrival of a new ++ * request for the queue. ++ * See the comments to the function bfq_bfqq_may_idle for the reasons ++ * why performing device idling is the best choice to boost the throughput ++ * and preserve service guarantees when bfq_bfqq_may_idle itself ++ * returns true. ++ */ ++static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++ ++ return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 && ++ bfq_bfqq_may_idle(bfqq); ++} ++ ++/* ++ * Select a queue for service. If we have a current queue in service, ++ * check whether to continue servicing it, or retrieve and set a new one. ++ */ ++static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ struct request *next_rq; ++ enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT; ++ ++ bfqq = bfqd->in_service_queue; ++ if (!bfqq) ++ goto new_queue; ++ ++ bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue"); ++ ++ if (bfq_may_expire_for_budg_timeout(bfqq) && ++ !timer_pending(&bfqd->idle_slice_timer) && ++ !bfq_bfqq_must_idle(bfqq)) ++ goto expire; ++ ++ next_rq = bfqq->next_rq; ++ /* ++ * If bfqq has requests queued and it has enough budget left to ++ * serve them, keep the queue, otherwise expire it. ++ */ ++ if (next_rq) { ++ if (bfq_serv_to_charge(next_rq, bfqq) > ++ bfq_bfqq_budget_left(bfqq)) { ++ reason = BFQ_BFQQ_BUDGET_EXHAUSTED; ++ goto expire; ++ } else { ++ /* ++ * The idle timer may be pending because we may ++ * not disable disk idling even when a new request ++ * arrives. ++ */ ++ if (timer_pending(&bfqd->idle_slice_timer)) { ++ /* ++ * If we get here: 1) at least a new request ++ * has arrived but we have not disabled the ++ * timer because the request was too small, ++ * 2) then the block layer has unplugged ++ * the device, causing the dispatch to be ++ * invoked. ++ * ++ * Since the device is unplugged, now the ++ * requests are probably large enough to ++ * provide a reasonable throughput. ++ * So we disable idling. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ del_timer(&bfqd->idle_slice_timer); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_idle_time(bfqq_group(bfqq)); ++#endif ++ } ++ goto keep_queue; ++ } ++ } ++ ++ /* ++ * No requests pending. However, if the in-service queue is idling ++ * for a new request, or has requests waiting for a completion and ++ * may idle after their completion, then keep it anyway. ++ */ ++ if (timer_pending(&bfqd->idle_slice_timer) || ++ (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) { ++ bfqq = NULL; ++ goto keep_queue; ++ } ++ ++ reason = BFQ_BFQQ_NO_MORE_REQUESTS; ++expire: ++ bfq_bfqq_expire(bfqd, bfqq, false, reason); ++new_queue: ++ bfqq = bfq_set_in_service_queue(bfqd); ++ bfq_log(bfqd, "select_queue: new queue %d returned", ++ bfqq ? bfqq->pid : 0); ++keep_queue: ++ return bfqq; ++} ++ ++static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */ ++ bfq_log_bfqq(bfqd, bfqq, ++ "raising period dur %u/%u msec, old coeff %u, w %d(%d)", ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqq->wr_coeff, ++ bfqq->entity.weight, bfqq->entity.orig_weight); ++ ++ BUG_ON(bfqq != bfqd->in_service_queue && entity->weight != ++ entity->orig_weight * bfqq->wr_coeff); ++ if (entity->prio_changed) ++ bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change"); ++ ++ /* ++ * If the queue was activated in a burst, or ++ * too much time has elapsed from the beginning ++ * of this weight-raising period, then end weight ++ * raising. ++ */ ++ if (bfq_bfqq_in_large_burst(bfqq) || ++ time_is_before_jiffies(bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time)) { ++ bfqq->last_wr_start_finish = jiffies; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ bfqq->last_wr_start_finish, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ bfq_bfqq_end_wr(bfqq); ++ } ++ } ++ /* Update weight both if it must be raised and if it must be lowered */ ++ if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1)) ++ __bfq_entity_update_weight_prio( ++ bfq_entity_service_tree(entity), ++ entity); ++} ++ ++/* ++ * Dispatch one request from bfqq, moving it to the request queue ++ * dispatch list. ++ */ ++static int bfq_dispatch_request(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ int dispatched = 0; ++ struct request *rq; ++ unsigned long service_to_charge; ++ ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ /* Follow expired path, else get first next available. */ ++ rq = bfq_check_fifo(bfqq); ++ if (!rq) ++ rq = bfqq->next_rq; ++ service_to_charge = bfq_serv_to_charge(rq, bfqq); ++ ++ if (service_to_charge > bfq_bfqq_budget_left(bfqq)) { ++ /* ++ * This may happen if the next rq is chosen in fifo order ++ * instead of sector order. The budget is properly ++ * dimensioned to be always sufficient to serve the next ++ * request only if it is chosen in sector order. The reason ++ * is that it would be quite inefficient and little useful ++ * to always make sure that the budget is large enough to ++ * serve even the possible next rq in fifo order. ++ * In fact, requests are seldom served in fifo order. ++ * ++ * Expire the queue for budget exhaustion, and make sure ++ * that the next act_budget is enough to serve the next ++ * request, even if it comes from the fifo expired path. ++ */ ++ bfqq->next_rq = rq; ++ /* ++ * Since this dispatch is failed, make sure that ++ * a new one will be performed ++ */ ++ if (!bfqd->rq_in_driver) ++ bfq_schedule_dispatch(bfqd); ++ goto expire; ++ } ++ ++ /* Finally, insert request into driver dispatch list. */ ++ bfq_bfqq_served(bfqq, service_to_charge); ++ bfq_dispatch_insert(bfqd->queue, rq); ++ ++ bfq_update_wr_data(bfqd, bfqq); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "dispatched %u sec req (%llu), budg left %d", ++ blk_rq_sectors(rq), ++ (long long unsigned)blk_rq_pos(rq), ++ bfq_bfqq_budget_left(bfqq)); ++ ++ dispatched++; ++ ++ if (!bfqd->in_service_bic) { ++ atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount); ++ bfqd->in_service_bic = RQ_BIC(rq); ++ } ++ ++ if (bfqd->busy_queues > 1 && ((!bfq_bfqq_sync(bfqq) && ++ dispatched >= bfqd->bfq_max_budget_async_rq) || ++ bfq_class_idle(bfqq))) ++ goto expire; ++ ++ return dispatched; ++ ++expire: ++ bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED); ++ return dispatched; ++} ++ ++static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq) ++{ ++ int dispatched = 0; ++ ++ while (bfqq->next_rq) { ++ bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq); ++ dispatched++; ++ } ++ ++ BUG_ON(!list_empty(&bfqq->fifo)); ++ return dispatched; ++} ++ ++/* ++ * Drain our current requests. ++ * Used for barriers and when switching io schedulers on-the-fly. ++ */ ++static int bfq_forced_dispatch(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq, *n; ++ struct bfq_service_tree *st; ++ int dispatched = 0; ++ ++ bfqq = bfqd->in_service_queue; ++ if (bfqq) ++ __bfq_bfqq_expire(bfqd, bfqq); ++ ++ /* ++ * Loop through classes, and be careful to leave the scheduler ++ * in a consistent state, as feedback mechanisms and vtime ++ * updates cannot be disabled during the process. ++ */ ++ list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) { ++ st = bfq_entity_service_tree(&bfqq->entity); ++ ++ dispatched += __bfq_forced_dispatch_bfqq(bfqq); ++ bfqq->max_budget = bfq_max_budget(bfqd); ++ ++ bfq_forget_idle(st); ++ } ++ ++ BUG_ON(bfqd->busy_queues != 0); ++ ++ return dispatched; ++} ++ ++static int bfq_dispatch_requests(struct request_queue *q, int force) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq; ++ int max_dispatch; ++ ++ bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues); ++ if (bfqd->busy_queues == 0) ++ return 0; ++ ++ if (unlikely(force)) ++ return bfq_forced_dispatch(bfqd); ++ ++ bfqq = bfq_select_queue(bfqd); ++ if (!bfqq) ++ return 0; ++ ++ if (bfq_class_idle(bfqq)) ++ max_dispatch = 1; ++ ++ if (!bfq_bfqq_sync(bfqq)) ++ max_dispatch = bfqd->bfq_max_budget_async_rq; ++ ++ if (!bfq_bfqq_sync(bfqq) && bfqq->dispatched >= max_dispatch) { ++ if (bfqd->busy_queues > 1) ++ return 0; ++ if (bfqq->dispatched >= 4 * max_dispatch) ++ return 0; ++ } ++ ++ if (bfqd->sync_flight != 0 && !bfq_bfqq_sync(bfqq)) ++ return 0; ++ ++ bfq_clear_bfqq_wait_request(bfqq); ++ BUG_ON(timer_pending(&bfqd->idle_slice_timer)); ++ ++ if (!bfq_dispatch_request(bfqd, bfqq)) ++ return 0; ++ ++ bfq_log_bfqq(bfqd, bfqq, "dispatched %s request", ++ bfq_bfqq_sync(bfqq) ? "sync" : "async"); ++ ++ return 1; ++} ++ ++/* ++ * Task holds one reference to the queue, dropped when task exits. Each rq ++ * in-flight on this queue also holds a reference, dropped when rq is freed. ++ * ++ * Queue lock must be held here. ++ */ ++static void bfq_put_queue(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ struct bfq_group *bfqg = bfqq_group(bfqq); ++#endif ++ ++ BUG_ON(atomic_read(&bfqq->ref) <= 0); ++ ++ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq, ++ atomic_read(&bfqq->ref)); ++ if (!atomic_dec_and_test(&bfqq->ref)) ++ return; ++ ++ BUG_ON(rb_first(&bfqq->sort_list)); ++ BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0); ++ BUG_ON(bfqq->entity.tree); ++ BUG_ON(bfq_bfqq_busy(bfqq)); ++ BUG_ON(bfqd->in_service_queue == bfqq); ++ ++ if (bfq_bfqq_sync(bfqq)) ++ /* ++ * The fact that this queue is being destroyed does not ++ * invalidate the fact that this queue may have been ++ * activated during the current burst. As a consequence, ++ * although the queue does not exist anymore, and hence ++ * needs to be removed from the burst list if there, ++ * the burst size has not to be decremented. ++ */ ++ hlist_del_init(&bfqq->burst_list_node); ++ ++ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p freed", bfqq); ++ ++ kmem_cache_free(bfq_pool, bfqq); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_put(bfqg); ++#endif ++} ++ ++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ if (bfqq == bfqd->in_service_queue) { ++ __bfq_bfqq_expire(bfqd, bfqq); ++ bfq_schedule_dispatch(bfqd); ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, ++ atomic_read(&bfqq->ref)); ++ ++ bfq_put_queue(bfqq); ++} ++ ++static void bfq_init_icq(struct io_cq *icq) ++{ ++ struct bfq_io_cq *bic = icq_to_bic(icq); ++ ++ bic->ttime.last_end_request = jiffies; ++} ++ ++static void bfq_exit_icq(struct io_cq *icq) ++{ ++ struct bfq_io_cq *bic = icq_to_bic(icq); ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ ++ if (bic->bfqq[BLK_RW_ASYNC]) { ++ bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_ASYNC]); ++ bic->bfqq[BLK_RW_ASYNC] = NULL; ++ } ++ ++ if (bic->bfqq[BLK_RW_SYNC]) { ++ bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]); ++ bic->bfqq[BLK_RW_SYNC] = NULL; ++ } ++} ++ ++/* ++ * Update the entity prio values; note that the new values will not ++ * be used until the next (re)activation. ++ */ ++static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic) ++{ ++ struct task_struct *tsk = current; ++ int ioprio_class; ++ ++ ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); ++ switch (ioprio_class) { ++ default: ++ dev_err(bfqq->bfqd->queue->backing_dev_info.dev, ++ "bfq: bad prio class %d\n", ioprio_class); ++ case IOPRIO_CLASS_NONE: ++ /* ++ * No prio set, inherit CPU scheduling settings. ++ */ ++ bfqq->new_ioprio = task_nice_ioprio(tsk); ++ bfqq->new_ioprio_class = task_nice_ioclass(tsk); ++ break; ++ case IOPRIO_CLASS_RT: ++ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ bfqq->new_ioprio_class = IOPRIO_CLASS_RT; ++ break; ++ case IOPRIO_CLASS_BE: ++ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ bfqq->new_ioprio_class = IOPRIO_CLASS_BE; ++ break; ++ case IOPRIO_CLASS_IDLE: ++ bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE; ++ bfqq->new_ioprio = 7; ++ bfq_clear_bfqq_idle_window(bfqq); ++ break; ++ } ++ ++ if (bfqq->new_ioprio < 0 || bfqq->new_ioprio >= IOPRIO_BE_NR) { ++ printk(KERN_CRIT "bfq_set_next_ioprio_data: new_ioprio %d\n", ++ bfqq->new_ioprio); ++ BUG(); ++ } ++ ++ bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio); ++ bfqq->entity.prio_changed = 1; ++} ++ ++static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio) ++{ ++ struct bfq_data *bfqd; ++ struct bfq_queue *bfqq, *new_bfqq; ++ unsigned long uninitialized_var(flags); ++ int ioprio = bic->icq.ioc->ioprio; ++ ++ bfqd = bfq_get_bfqd_locked(&(bic->icq.q->elevator->elevator_data), ++ &flags); ++ /* ++ * This condition may trigger on a newly created bic, be sure to ++ * drop the lock before returning. ++ */ ++ if (unlikely(!bfqd) || likely(bic->ioprio == ioprio)) ++ goto out; ++ ++ bic->ioprio = ioprio; ++ ++ bfqq = bic->bfqq[BLK_RW_ASYNC]; ++ if (bfqq) { ++ new_bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic, ++ GFP_ATOMIC); ++ if (new_bfqq) { ++ bic->bfqq[BLK_RW_ASYNC] = new_bfqq; ++ bfq_log_bfqq(bfqd, bfqq, ++ "check_ioprio_change: bfqq %p %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ bfq_put_queue(bfqq); ++ } ++ } ++ ++ bfqq = bic->bfqq[BLK_RW_SYNC]; ++ if (bfqq) ++ bfq_set_next_ioprio_data(bfqq, bic); ++ ++out: ++ bfq_put_bfqd_unlock(bfqd, &flags); ++} ++ ++static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic, pid_t pid, int is_sync) ++{ ++ RB_CLEAR_NODE(&bfqq->entity.rb_node); ++ INIT_LIST_HEAD(&bfqq->fifo); ++ INIT_HLIST_NODE(&bfqq->burst_list_node); ++ ++ atomic_set(&bfqq->ref, 0); ++ bfqq->bfqd = bfqd; ++ ++ if (bic) ++ bfq_set_next_ioprio_data(bfqq, bic); ++ ++ if (is_sync) { ++ if (!bfq_class_idle(bfqq)) ++ bfq_mark_bfqq_idle_window(bfqq); ++ bfq_mark_bfqq_sync(bfqq); ++ } else ++ bfq_clear_bfqq_sync(bfqq); ++ bfq_mark_bfqq_IO_bound(bfqq); ++ ++ /* Tentative initial value to trade off between thr and lat */ ++ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3; ++ bfqq->pid = pid; ++ ++ bfqq->wr_coeff = 1; ++ bfqq->last_wr_start_finish = 0; ++ /* ++ * Set to the value for which bfqq will not be deemed as ++ * soft rt when it becomes backlogged. ++ */ ++ bfqq->soft_rt_next_start = bfq_infinity_from_now(jiffies); ++} ++ ++static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd, ++ struct bio *bio, int is_sync, ++ struct bfq_io_cq *bic, ++ gfp_t gfp_mask) ++{ ++ struct bfq_group *bfqg; ++ struct bfq_queue *bfqq, *new_bfqq = NULL; ++ struct blkcg *blkcg; ++ ++retry: ++ rcu_read_lock(); ++ ++ blkcg = bio_blkcg(bio); ++ bfqg = bfq_find_alloc_group(bfqd, blkcg); ++ /* bic always exists here */ ++ bfqq = bic_to_bfqq(bic, is_sync); ++ ++ /* ++ * Always try a new alloc if we fall back to the OOM bfqq ++ * originally, since it should just be a temporary situation. ++ */ ++ if (!bfqq || bfqq == &bfqd->oom_bfqq) { ++ bfqq = NULL; ++ if (new_bfqq) { ++ bfqq = new_bfqq; ++ new_bfqq = NULL; ++ } else if (gfpflags_allow_blocking(gfp_mask)) { ++ rcu_read_unlock(); ++ spin_unlock_irq(bfqd->queue->queue_lock); ++ new_bfqq = kmem_cache_alloc_node(bfq_pool, ++ gfp_mask | __GFP_ZERO, ++ bfqd->queue->node); ++ spin_lock_irq(bfqd->queue->queue_lock); ++ if (new_bfqq) ++ goto retry; ++ } else { ++ bfqq = kmem_cache_alloc_node(bfq_pool, ++ gfp_mask | __GFP_ZERO, ++ bfqd->queue->node); ++ } ++ ++ if (bfqq) { ++ bfq_init_bfqq(bfqd, bfqq, bic, current->pid, ++ is_sync); ++ bfq_init_entity(&bfqq->entity, bfqg); ++ bfq_log_bfqq(bfqd, bfqq, "allocated"); ++ } else { ++ bfqq = &bfqd->oom_bfqq; ++ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq"); ++ } ++ } ++ ++ if (new_bfqq) ++ kmem_cache_free(bfq_pool, new_bfqq); ++ ++ rcu_read_unlock(); ++ ++ return bfqq; ++} ++ ++static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, ++ int ioprio_class, int ioprio) ++{ ++ switch (ioprio_class) { ++ case IOPRIO_CLASS_RT: ++ return &bfqg->async_bfqq[0][ioprio]; ++ case IOPRIO_CLASS_NONE: ++ ioprio = IOPRIO_NORM; ++ /* fall through */ ++ case IOPRIO_CLASS_BE: ++ return &bfqg->async_bfqq[1][ioprio]; ++ case IOPRIO_CLASS_IDLE: ++ return &bfqg->async_idle_bfqq; ++ default: ++ BUG(); ++ } ++} ++ ++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, ++ struct bio *bio, int is_sync, ++ struct bfq_io_cq *bic, gfp_t gfp_mask) ++{ ++ const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); ++ struct bfq_queue **async_bfqq = NULL; ++ struct bfq_queue *bfqq = NULL; ++ ++ if (!is_sync) { ++ struct blkcg *blkcg; ++ struct bfq_group *bfqg; ++ ++ rcu_read_lock(); ++ blkcg = bio_blkcg(bio); ++ rcu_read_unlock(); ++ bfqg = bfq_find_alloc_group(bfqd, blkcg); ++ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class, ++ ioprio); ++ bfqq = *async_bfqq; ++ } ++ ++ if (!bfqq) ++ bfqq = bfq_find_alloc_queue(bfqd, bio, is_sync, bic, gfp_mask); ++ ++ /* ++ * Pin the queue now that it's allocated, scheduler exit will ++ * prune it. ++ */ ++ if (!is_sync && !(*async_bfqq)) { ++ atomic_inc(&bfqq->ref); ++ bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ *async_bfqq = bfqq; ++ } ++ ++ atomic_inc(&bfqq->ref); ++ bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, ++ atomic_read(&bfqq->ref)); ++ return bfqq; ++} ++ ++static void bfq_update_io_thinktime(struct bfq_data *bfqd, ++ struct bfq_io_cq *bic) ++{ ++ unsigned long elapsed = jiffies - bic->ttime.last_end_request; ++ unsigned long ttime = min(elapsed, 2UL * bfqd->bfq_slice_idle); ++ ++ bic->ttime.ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8; ++ bic->ttime.ttime_total = (7*bic->ttime.ttime_total + 256*ttime) / 8; ++ bic->ttime.ttime_mean = (bic->ttime.ttime_total + 128) / ++ bic->ttime.ttime_samples; ++} ++ ++static void bfq_update_io_seektime(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ sector_t sdist; ++ u64 total; ++ ++ if (bfqq->last_request_pos < blk_rq_pos(rq)) ++ sdist = blk_rq_pos(rq) - bfqq->last_request_pos; ++ else ++ sdist = bfqq->last_request_pos - blk_rq_pos(rq); ++ ++ /* ++ * Don't allow the seek distance to get too large from the ++ * odd fragment, pagein, etc. ++ */ ++ if (bfqq->seek_samples == 0) /* first request, not really a seek */ ++ sdist = 0; ++ else if (bfqq->seek_samples <= 60) /* second & third seek */ ++ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*1024); ++ else ++ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*64); ++ ++ bfqq->seek_samples = (7*bfqq->seek_samples + 256) / 8; ++ bfqq->seek_total = (7*bfqq->seek_total + (u64)256*sdist) / 8; ++ total = bfqq->seek_total + (bfqq->seek_samples/2); ++ do_div(total, bfqq->seek_samples); ++ bfqq->seek_mean = (sector_t)total; ++ ++ bfq_log_bfqq(bfqd, bfqq, "dist=%llu mean=%llu", (u64)sdist, ++ (u64)bfqq->seek_mean); ++} ++ ++/* ++ * Disable idle window if the process thinks too long or seeks so much that ++ * it doesn't matter. ++ */ ++static void bfq_update_idle_window(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic) ++{ ++ int enable_idle; ++ ++ /* Don't idle for async or idle io prio class. */ ++ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq)) ++ return; ++ ++ enable_idle = bfq_bfqq_idle_window(bfqq); ++ ++ if (atomic_read(&bic->icq.ioc->active_ref) == 0 || ++ bfqd->bfq_slice_idle == 0 || ++ (bfqd->hw_tag && BFQQ_SEEKY(bfqq) && ++ bfqq->wr_coeff == 1)) ++ enable_idle = 0; ++ else if (bfq_sample_valid(bic->ttime.ttime_samples)) { ++ if (bic->ttime.ttime_mean > bfqd->bfq_slice_idle && ++ bfqq->wr_coeff == 1) ++ enable_idle = 0; ++ else ++ enable_idle = 1; ++ } ++ bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d", ++ enable_idle); ++ ++ if (enable_idle) ++ bfq_mark_bfqq_idle_window(bfqq); ++ else ++ bfq_clear_bfqq_idle_window(bfqq); ++} ++ ++/* ++ * Called when a new fs request (rq) is added to bfqq. Check if there's ++ * something we should do about it. ++ */ ++static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ struct bfq_io_cq *bic = RQ_BIC(rq); ++ ++ if (rq->cmd_flags & REQ_META) ++ bfqq->meta_pending++; ++ ++ bfq_update_io_thinktime(bfqd, bic); ++ bfq_update_io_seektime(bfqd, bfqq, rq); ++ if (!BFQQ_SEEKY(bfqq) && bfq_bfqq_constantly_seeky(bfqq)) { ++ bfq_clear_bfqq_constantly_seeky(bfqq); ++ if (!blk_queue_nonrot(bfqd->queue)) { ++ BUG_ON(!bfqd->const_seeky_busy_in_flight_queues); ++ bfqd->const_seeky_busy_in_flight_queues--; ++ } ++ } ++ if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 || ++ !BFQQ_SEEKY(bfqq)) ++ bfq_update_idle_window(bfqd, bfqq, bic); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "rq_enqueued: idle_window=%d (seeky %d, mean %llu)", ++ bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq), ++ (long long unsigned)bfqq->seek_mean); ++ ++ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); ++ ++ if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) { ++ bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 && ++ blk_rq_sectors(rq) < 32; ++ bool budget_timeout = bfq_bfqq_budget_timeout(bfqq); ++ ++ /* ++ * There is just this request queued: if the request ++ * is small and the queue is not to be expired, then ++ * just exit. ++ * ++ * In this way, if the disk is being idled to wait for ++ * a new request from the in-service queue, we avoid ++ * unplugging the device and committing the disk to serve ++ * just a small request. On the contrary, we wait for ++ * the block layer to decide when to unplug the device: ++ * hopefully, new requests will be merged to this one ++ * quickly, then the device will be unplugged and ++ * larger requests will be dispatched. ++ */ ++ if (small_req && !budget_timeout) ++ return; ++ ++ /* ++ * A large enough request arrived, or the queue is to ++ * be expired: in both cases disk idling is to be ++ * stopped, so clear wait_request flag and reset ++ * timer. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ del_timer(&bfqd->idle_slice_timer); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_idle_time(bfqq_group(bfqq)); ++#endif ++ ++ /* ++ * The queue is not empty, because a new request just ++ * arrived. Hence we can safely expire the queue, in ++ * case of budget timeout, without risking that the ++ * timestamps of the queue are not updated correctly. ++ * See [1] for more details. ++ */ ++ if (budget_timeout) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_BUDGET_TIMEOUT); ++ ++ /* ++ * Let the request rip immediately, or let a new queue be ++ * selected if bfqq has just been expired. ++ */ ++ __blk_run_queue(bfqd->queue); ++ } ++} ++ ++static void bfq_insert_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ assert_spin_locked(bfqd->queue->queue_lock); ++ ++ bfq_add_request(rq); ++ ++ rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; ++ list_add_tail(&rq->queuelist, &bfqq->fifo); ++ ++ bfq_rq_enqueued(bfqd, bfqq, rq); ++} ++ ++static void bfq_update_hw_tag(struct bfq_data *bfqd) ++{ ++ bfqd->max_rq_in_driver = max(bfqd->max_rq_in_driver, ++ bfqd->rq_in_driver); ++ ++ if (bfqd->hw_tag == 1) ++ return; ++ ++ /* ++ * This sample is valid if the number of outstanding requests ++ * is large enough to allow a queueing behavior. Note that the ++ * sum is not exact, as it's not taking into account deactivated ++ * requests. ++ */ ++ if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD) ++ return; ++ ++ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES) ++ return; ++ ++ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD; ++ bfqd->max_rq_in_driver = 0; ++ bfqd->hw_tag_samples = 0; ++} ++ ++static void bfq_completed_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ bool sync = bfq_bfqq_sync(bfqq); ++ ++ bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left (%d)", ++ blk_rq_sectors(rq), sync); ++ ++ bfq_update_hw_tag(bfqd); ++ ++ BUG_ON(!bfqd->rq_in_driver); ++ BUG_ON(!bfqq->dispatched); ++ bfqd->rq_in_driver--; ++ bfqq->dispatched--; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_completion(bfqq_group(bfqq), ++ rq_start_time_ns(rq), ++ rq_io_start_time_ns(rq), rq->cmd_flags); ++#endif ++ ++ if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) { ++ bfq_weights_tree_remove(bfqd, &bfqq->entity, ++ &bfqd->queue_weights_tree); ++ if (!blk_queue_nonrot(bfqd->queue)) { ++ BUG_ON(!bfqd->busy_in_flight_queues); ++ bfqd->busy_in_flight_queues--; ++ if (bfq_bfqq_constantly_seeky(bfqq)) { ++ BUG_ON(!bfqd-> ++ const_seeky_busy_in_flight_queues); ++ bfqd->const_seeky_busy_in_flight_queues--; ++ } ++ } ++ } ++ ++ if (sync) { ++ bfqd->sync_flight--; ++ RQ_BIC(rq)->ttime.last_end_request = jiffies; ++ } ++ ++ /* ++ * If we are waiting to discover whether the request pattern of the ++ * task associated with the queue is actually isochronous, and ++ * both requisites for this condition to hold are satisfied, then ++ * compute soft_rt_next_start (see the comments to the function ++ * bfq_bfqq_softrt_next_start()). ++ */ ++ if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 && ++ RB_EMPTY_ROOT(&bfqq->sort_list)) ++ bfqq->soft_rt_next_start = ++ bfq_bfqq_softrt_next_start(bfqd, bfqq); ++ ++ /* ++ * If this is the in-service queue, check if it needs to be expired, ++ * or if we want to idle in case it has no pending requests. ++ */ ++ if (bfqd->in_service_queue == bfqq) { ++ if (bfq_bfqq_budget_new(bfqq)) ++ bfq_set_budget_timeout(bfqd); ++ ++ if (bfq_bfqq_must_idle(bfqq)) { ++ bfq_arm_slice_timer(bfqd); ++ goto out; ++ } else if (bfq_may_expire_for_budg_timeout(bfqq)) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_BUDGET_TIMEOUT); ++ else if (RB_EMPTY_ROOT(&bfqq->sort_list) && ++ (bfqq->dispatched == 0 || ++ !bfq_bfqq_may_idle(bfqq))) ++ bfq_bfqq_expire(bfqd, bfqq, false, ++ BFQ_BFQQ_NO_MORE_REQUESTS); ++ } ++ ++ if (!bfqd->rq_in_driver) ++ bfq_schedule_dispatch(bfqd); ++ ++out: ++ return; ++} ++ ++static int __bfq_may_queue(struct bfq_queue *bfqq) ++{ ++ if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) { ++ bfq_clear_bfqq_must_alloc(bfqq); ++ return ELV_MQUEUE_MUST; ++ } ++ ++ return ELV_MQUEUE_MAY; ++} ++ ++static int bfq_may_queue(struct request_queue *q, int rw) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct task_struct *tsk = current; ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq; ++ ++ /* ++ * Don't force setup of a queue from here, as a call to may_queue ++ * does not necessarily imply that a request actually will be ++ * queued. So just lookup a possibly existing queue, or return ++ * 'may queue' if that fails. ++ */ ++ bic = bfq_bic_lookup(bfqd, tsk->io_context); ++ if (!bic) ++ return ELV_MQUEUE_MAY; ++ ++ bfqq = bic_to_bfqq(bic, rw_is_sync(rw)); ++ if (bfqq) ++ return __bfq_may_queue(bfqq); ++ ++ return ELV_MQUEUE_MAY; ++} ++ ++/* ++ * Queue lock held here. ++ */ ++static void bfq_put_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ if (bfqq) { ++ const int rw = rq_data_dir(rq); ++ ++ BUG_ON(!bfqq->allocated[rw]); ++ bfqq->allocated[rw]--; ++ ++ rq->elv.priv[0] = NULL; ++ rq->elv.priv[1] = NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ bfq_put_queue(bfqq); ++ } ++} ++ ++/* ++ * Allocate bfq data structures associated with this request. ++ */ ++static int bfq_set_request(struct request_queue *q, struct request *rq, ++ struct bio *bio, gfp_t gfp_mask) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq); ++ const int rw = rq_data_dir(rq); ++ const int is_sync = rq_is_sync(rq); ++ struct bfq_queue *bfqq; ++ unsigned long flags; ++ ++ might_sleep_if(gfpflags_allow_blocking(gfp_mask)); ++ ++ bfq_check_ioprio_change(bic, bio); ++ ++ spin_lock_irqsave(q->queue_lock, flags); ++ ++ if (!bic) ++ goto queue_fail; ++ ++ bfq_bic_update_cgroup(bic, bio); ++ ++ bfqq = bic_to_bfqq(bic, is_sync); ++ if (!bfqq || bfqq == &bfqd->oom_bfqq) { ++ bfqq = bfq_get_queue(bfqd, bio, is_sync, bic, gfp_mask); ++ bic_set_bfqq(bic, bfqq, is_sync); ++ if (is_sync) { ++ if (bfqd->large_burst) ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ else ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ } ++ } ++ ++ bfqq->allocated[rw]++; ++ atomic_inc(&bfqq->ref); ++ bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, ++ atomic_read(&bfqq->ref)); ++ ++ rq->elv.priv[0] = bic; ++ rq->elv.priv[1] = bfqq; ++ ++ spin_unlock_irqrestore(q->queue_lock, flags); ++ ++ return 0; ++ ++queue_fail: ++ bfq_schedule_dispatch(bfqd); ++ spin_unlock_irqrestore(q->queue_lock, flags); ++ ++ return 1; ++} ++ ++static void bfq_kick_queue(struct work_struct *work) ++{ ++ struct bfq_data *bfqd = ++ container_of(work, struct bfq_data, unplug_work); ++ struct request_queue *q = bfqd->queue; ++ ++ spin_lock_irq(q->queue_lock); ++ __blk_run_queue(q); ++ spin_unlock_irq(q->queue_lock); ++} ++ ++/* ++ * Handler of the expiration of the timer running if the in-service queue ++ * is idling inside its time slice. ++ */ ++static void bfq_idle_slice_timer(unsigned long data) ++{ ++ struct bfq_data *bfqd = (struct bfq_data *)data; ++ struct bfq_queue *bfqq; ++ unsigned long flags; ++ enum bfqq_expiration reason; ++ ++ spin_lock_irqsave(bfqd->queue->queue_lock, flags); ++ ++ bfqq = bfqd->in_service_queue; ++ /* ++ * Theoretical race here: the in-service queue can be NULL or ++ * different from the queue that was idling if the timer handler ++ * spins on the queue_lock and a new request arrives for the ++ * current queue and there is a full dispatch cycle that changes ++ * the in-service queue. This can hardly happen, but in the worst ++ * case we just expire a queue too early. ++ */ ++ if (bfqq) { ++ bfq_log_bfqq(bfqd, bfqq, "slice_timer expired"); ++ if (bfq_bfqq_budget_timeout(bfqq)) ++ /* ++ * Also here the queue can be safely expired ++ * for budget timeout without wasting ++ * guarantees ++ */ ++ reason = BFQ_BFQQ_BUDGET_TIMEOUT; ++ else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0) ++ /* ++ * The queue may not be empty upon timer expiration, ++ * because we may not disable the timer when the ++ * first request of the in-service queue arrives ++ * during disk idling. ++ */ ++ reason = BFQ_BFQQ_TOO_IDLE; ++ else ++ goto schedule_dispatch; ++ ++ bfq_bfqq_expire(bfqd, bfqq, true, reason); ++ } ++ ++schedule_dispatch: ++ bfq_schedule_dispatch(bfqd); ++ ++ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags); ++} ++ ++static void bfq_shutdown_timer_wq(struct bfq_data *bfqd) ++{ ++ del_timer_sync(&bfqd->idle_slice_timer); ++ cancel_work_sync(&bfqd->unplug_work); ++} ++ ++static void __bfq_put_async_bfqq(struct bfq_data *bfqd, ++ struct bfq_queue **bfqq_ptr) ++{ ++ struct bfq_group *root_group = bfqd->root_group; ++ struct bfq_queue *bfqq = *bfqq_ptr; ++ ++ bfq_log(bfqd, "put_async_bfqq: %p", bfqq); ++ if (bfqq) { ++ bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group); ++ bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ bfq_put_queue(bfqq); ++ *bfqq_ptr = NULL; ++ } ++} ++ ++/* ++ * Release all the bfqg references to its async queues. If we are ++ * deallocating the group these queues may still contain requests, so ++ * we reparent them to the root cgroup (i.e., the only one that will ++ * exist for sure until all the requests on a device are gone). ++ */ ++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg) ++{ ++ int i, j; ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < IOPRIO_BE_NR; j++) ++ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]); ++ ++ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq); ++} ++ ++static void bfq_exit_queue(struct elevator_queue *e) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ struct request_queue *q = bfqd->queue; ++ struct bfq_queue *bfqq, *n; ++ ++ bfq_shutdown_timer_wq(bfqd); ++ ++ spin_lock_irq(q->queue_lock); ++ ++ BUG_ON(bfqd->in_service_queue); ++ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) ++ bfq_deactivate_bfqq(bfqd, bfqq, 0); ++ ++ spin_unlock_irq(q->queue_lock); ++ ++ bfq_shutdown_timer_wq(bfqd); ++ ++ synchronize_rcu(); ++ ++ BUG_ON(timer_pending(&bfqd->idle_slice_timer)); ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ blkcg_deactivate_policy(q, &blkcg_policy_bfq); ++#else ++ kfree(bfqd->root_group); ++#endif ++ ++ kfree(bfqd); ++} ++ ++static void bfq_init_root_group(struct bfq_group *root_group, ++ struct bfq_data *bfqd) ++{ ++ int i; ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ root_group->entity.parent = NULL; ++ root_group->my_entity = NULL; ++ root_group->bfqd = bfqd; ++#endif ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) ++ root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; ++} ++ ++static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) ++{ ++ struct bfq_data *bfqd; ++ struct elevator_queue *eq; ++ ++ eq = elevator_alloc(q, e); ++ if (!eq) ++ return -ENOMEM; ++ ++ bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node); ++ if (!bfqd) { ++ kobject_put(&eq->kobj); ++ return -ENOMEM; ++ } ++ eq->elevator_data = bfqd; ++ ++ /* ++ * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues. ++ * Grab a permanent reference to it, so that the normal code flow ++ * will not attempt to free it. ++ */ ++ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0); ++ atomic_inc(&bfqd->oom_bfqq.ref); ++ bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO; ++ bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE; ++ bfqd->oom_bfqq.entity.new_weight = ++ bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio); ++ /* ++ * Trigger weight initialization, according to ioprio, at the ++ * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio ++ * class won't be changed any more. ++ */ ++ bfqd->oom_bfqq.entity.prio_changed = 1; ++ ++ bfqd->queue = q; ++ ++ spin_lock_irq(q->queue_lock); ++ q->elevator = eq; ++ spin_unlock_irq(q->queue_lock); ++ ++ bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node); ++ if (!bfqd->root_group) ++ goto out_free; ++ bfq_init_root_group(bfqd->root_group, bfqd); ++ bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqd->active_numerous_groups = 0; ++#endif ++ ++ init_timer(&bfqd->idle_slice_timer); ++ bfqd->idle_slice_timer.function = bfq_idle_slice_timer; ++ bfqd->idle_slice_timer.data = (unsigned long)bfqd; ++ ++ bfqd->queue_weights_tree = RB_ROOT; ++ bfqd->group_weights_tree = RB_ROOT; ++ ++ INIT_WORK(&bfqd->unplug_work, bfq_kick_queue); ++ ++ INIT_LIST_HEAD(&bfqd->active_list); ++ INIT_LIST_HEAD(&bfqd->idle_list); ++ INIT_HLIST_HEAD(&bfqd->burst_list); ++ ++ bfqd->hw_tag = -1; ++ ++ bfqd->bfq_max_budget = bfq_default_max_budget; ++ ++ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0]; ++ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1]; ++ bfqd->bfq_back_max = bfq_back_max; ++ bfqd->bfq_back_penalty = bfq_back_penalty; ++ bfqd->bfq_slice_idle = bfq_slice_idle; ++ bfqd->bfq_class_idle_last_service = 0; ++ bfqd->bfq_max_budget_async_rq = bfq_max_budget_async_rq; ++ bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async; ++ bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync; ++ ++ bfqd->bfq_requests_within_timer = 120; ++ ++ bfqd->bfq_large_burst_thresh = 11; ++ bfqd->bfq_burst_interval = msecs_to_jiffies(500); ++ ++ bfqd->low_latency = true; ++ ++ bfqd->bfq_wr_coeff = 20; ++ bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300); ++ bfqd->bfq_wr_max_time = 0; ++ bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000); ++ bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500); ++ bfqd->bfq_wr_max_softrt_rate = 7000; /* ++ * Approximate rate required ++ * to playback or record a ++ * high-definition compressed ++ * video. ++ */ ++ bfqd->wr_busy_queues = 0; ++ bfqd->busy_in_flight_queues = 0; ++ bfqd->const_seeky_busy_in_flight_queues = 0; ++ ++ /* ++ * Begin by assuming, optimistically, that the device peak rate is ++ * equal to the highest reference rate. ++ */ ++ bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] * ++ T_fast[blk_queue_nonrot(bfqd->queue)]; ++ bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)]; ++ bfqd->device_speed = BFQ_BFQD_FAST; ++ ++ return 0; ++ ++out_free: ++ kfree(bfqd); ++ kobject_put(&eq->kobj); ++ return -ENOMEM; ++} ++ ++static void bfq_slab_kill(void) ++{ ++ if (bfq_pool) ++ kmem_cache_destroy(bfq_pool); ++} ++ ++static int __init bfq_slab_setup(void) ++{ ++ bfq_pool = KMEM_CACHE(bfq_queue, 0); ++ if (!bfq_pool) ++ return -ENOMEM; ++ return 0; ++} ++ ++static ssize_t bfq_var_show(unsigned int var, char *page) ++{ ++ return sprintf(page, "%d\n", var); ++} ++ ++static ssize_t bfq_var_store(unsigned long *var, const char *page, ++ size_t count) ++{ ++ unsigned long new_val; ++ int ret = kstrtoul(page, 10, &new_val); ++ ++ if (ret == 0) ++ *var = new_val; ++ ++ return count; ++} ++ ++static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ? ++ jiffies_to_msecs(bfqd->bfq_wr_max_time) : ++ jiffies_to_msecs(bfq_wr_duration(bfqd))); ++} ++ ++static ssize_t bfq_weights_show(struct elevator_queue *e, char *page) ++{ ++ struct bfq_queue *bfqq; ++ struct bfq_data *bfqd = e->elevator_data; ++ ssize_t num_char = 0; ++ ++ num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n", ++ bfqd->queued); ++ ++ spin_lock_irq(bfqd->queue->queue_lock); ++ ++ num_char += sprintf(page + num_char, "Active:\n"); ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) { ++ num_char += sprintf(page + num_char, ++ "pid%d: weight %hu, nr_queued %d %d, dur %d/%u\n", ++ bfqq->pid, ++ bfqq->entity.weight, ++ bfqq->queued[0], ++ bfqq->queued[1], ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ num_char += sprintf(page + num_char, "Idle:\n"); ++ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) { ++ num_char += sprintf(page + num_char, ++ "pid%d: weight %hu, dur %d/%u\n", ++ bfqq->pid, ++ bfqq->entity.weight, ++ jiffies_to_msecs(jiffies - ++ bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ spin_unlock_irq(bfqd->queue->queue_lock); ++ ++ return num_char; ++} ++ ++#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ ++static ssize_t __FUNC(struct elevator_queue *e, char *page) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ unsigned int __data = __VAR; \ ++ if (__CONV) \ ++ __data = jiffies_to_msecs(__data); \ ++ return bfq_var_show(__data, (page)); \ ++} ++SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 1); ++SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 1); ++SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0); ++SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0); ++SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 1); ++SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0); ++SHOW_FUNCTION(bfq_max_budget_async_rq_show, ++ bfqd->bfq_max_budget_async_rq, 0); ++SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout[BLK_RW_SYNC], 1); ++SHOW_FUNCTION(bfq_timeout_async_show, bfqd->bfq_timeout[BLK_RW_ASYNC], 1); ++SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0); ++SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0); ++SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1); ++SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1); ++SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async, ++ 1); ++SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0); ++#undef SHOW_FUNCTION ++ ++#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ ++static ssize_t \ ++__FUNC(struct elevator_queue *e, const char *page, size_t count) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ unsigned long uninitialized_var(__data); \ ++ int ret = bfq_var_store(&__data, (page), count); \ ++ if (__data < (MIN)) \ ++ __data = (MIN); \ ++ else if (__data > (MAX)) \ ++ __data = (MAX); \ ++ if (__CONV) \ ++ *(__PTR) = msecs_to_jiffies(__data); \ ++ else \ ++ *(__PTR) = __data; \ ++ return ret; \ ++} ++STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0); ++STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1, ++ INT_MAX, 0); ++STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_max_budget_async_rq_store, &bfqd->bfq_max_budget_async_rq, ++ 1, INT_MAX, 0); ++STORE_FUNCTION(bfq_timeout_async_store, &bfqd->bfq_timeout[BLK_RW_ASYNC], 0, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0); ++STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX, ++ 1); ++STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_min_inter_arr_async_store, ++ &bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0, ++ INT_MAX, 0); ++#undef STORE_FUNCTION ++ ++/* do nothing for the moment */ ++static ssize_t bfq_weights_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ return count; ++} ++ ++static unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd) ++{ ++ u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]); ++ ++ if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES) ++ return bfq_calc_max_budget(bfqd->peak_rate, timeout); ++ else ++ return bfq_default_max_budget; ++} ++ ++static ssize_t bfq_max_budget_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data == 0) ++ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd); ++ else { ++ if (__data > INT_MAX) ++ __data = INT_MAX; ++ bfqd->bfq_max_budget = __data; ++ } ++ ++ bfqd->bfq_user_max_budget = __data; ++ ++ return ret; ++} ++ ++static ssize_t bfq_timeout_sync_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data < 1) ++ __data = 1; ++ else if (__data > INT_MAX) ++ __data = INT_MAX; ++ ++ bfqd->bfq_timeout[BLK_RW_SYNC] = msecs_to_jiffies(__data); ++ if (bfqd->bfq_user_max_budget == 0) ++ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd); ++ ++ return ret; ++} ++ ++static ssize_t bfq_low_latency_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data > 1) ++ __data = 1; ++ if (__data == 0 && bfqd->low_latency != 0) ++ bfq_end_wr(bfqd); ++ bfqd->low_latency = __data; ++ ++ return ret; ++} ++ ++#define BFQ_ATTR(name) \ ++ __ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store) ++ ++static struct elv_fs_entry bfq_attrs[] = { ++ BFQ_ATTR(fifo_expire_sync), ++ BFQ_ATTR(fifo_expire_async), ++ BFQ_ATTR(back_seek_max), ++ BFQ_ATTR(back_seek_penalty), ++ BFQ_ATTR(slice_idle), ++ BFQ_ATTR(max_budget), ++ BFQ_ATTR(max_budget_async_rq), ++ BFQ_ATTR(timeout_sync), ++ BFQ_ATTR(timeout_async), ++ BFQ_ATTR(low_latency), ++ BFQ_ATTR(wr_coeff), ++ BFQ_ATTR(wr_max_time), ++ BFQ_ATTR(wr_rt_max_time), ++ BFQ_ATTR(wr_min_idle_time), ++ BFQ_ATTR(wr_min_inter_arr_async), ++ BFQ_ATTR(wr_max_softrt_rate), ++ BFQ_ATTR(weights), ++ __ATTR_NULL ++}; ++ ++static struct elevator_type iosched_bfq = { ++ .ops = { ++ .elevator_merge_fn = bfq_merge, ++ .elevator_merged_fn = bfq_merged_request, ++ .elevator_merge_req_fn = bfq_merged_requests, ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ .elevator_bio_merged_fn = bfq_bio_merged, ++#endif ++ .elevator_allow_merge_fn = bfq_allow_merge, ++ .elevator_dispatch_fn = bfq_dispatch_requests, ++ .elevator_add_req_fn = bfq_insert_request, ++ .elevator_activate_req_fn = bfq_activate_request, ++ .elevator_deactivate_req_fn = bfq_deactivate_request, ++ .elevator_completed_req_fn = bfq_completed_request, ++ .elevator_former_req_fn = elv_rb_former_request, ++ .elevator_latter_req_fn = elv_rb_latter_request, ++ .elevator_init_icq_fn = bfq_init_icq, ++ .elevator_exit_icq_fn = bfq_exit_icq, ++ .elevator_set_req_fn = bfq_set_request, ++ .elevator_put_req_fn = bfq_put_request, ++ .elevator_may_queue_fn = bfq_may_queue, ++ .elevator_init_fn = bfq_init_queue, ++ .elevator_exit_fn = bfq_exit_queue, ++ }, ++ .icq_size = sizeof(struct bfq_io_cq), ++ .icq_align = __alignof__(struct bfq_io_cq), ++ .elevator_attrs = bfq_attrs, ++ .elevator_name = "bfq", ++ .elevator_owner = THIS_MODULE, ++}; ++ ++static int __init bfq_init(void) ++{ ++ int ret; ++ ++ /* ++ * Can be 0 on HZ < 1000 setups. ++ */ ++ if (bfq_slice_idle == 0) ++ bfq_slice_idle = 1; ++ ++ if (bfq_timeout_async == 0) ++ bfq_timeout_async = 1; ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ ret = blkcg_policy_register(&blkcg_policy_bfq); ++ if (ret) ++ return ret; ++#endif ++ ++ ret = -ENOMEM; ++ if (bfq_slab_setup()) ++ goto err_pol_unreg; ++ ++ /* ++ * Times to load large popular applications for the typical systems ++ * installed on the reference devices (see the comments before the ++ * definitions of the two arrays). ++ */ ++ T_slow[0] = msecs_to_jiffies(2600); ++ T_slow[1] = msecs_to_jiffies(1000); ++ T_fast[0] = msecs_to_jiffies(5500); ++ T_fast[1] = msecs_to_jiffies(2000); ++ ++ /* ++ * Thresholds that determine the switch between speed classes (see ++ * the comments before the definition of the array). ++ */ ++ device_speed_thresh[0] = (R_fast[0] + R_slow[0]) / 2; ++ device_speed_thresh[1] = (R_fast[1] + R_slow[1]) / 2; ++ ++ ret = elv_register(&iosched_bfq); ++ if (ret) ++ goto err_pol_unreg; ++ ++ pr_info("BFQ I/O-scheduler: v7r11"); ++ ++ return 0; ++ ++err_pol_unreg: ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ blkcg_policy_unregister(&blkcg_policy_bfq); ++#endif ++ return ret; ++} ++ ++static void __exit bfq_exit(void) ++{ ++ elv_unregister(&iosched_bfq); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ blkcg_policy_unregister(&blkcg_policy_bfq); ++#endif ++ bfq_slab_kill(); ++} ++ ++module_init(bfq_init); ++module_exit(bfq_exit); ++ ++MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente"); ++MODULE_LICENSE("GPL"); +diff --git a/block/bfq-sched.c b/block/bfq-sched.c +new file mode 100644 +index 0000000..a64fec1 +--- /dev/null ++++ b/block/bfq-sched.c +@@ -0,0 +1,1200 @@ ++/* ++ * BFQ: Hierarchical B-WF2Q+ scheduler. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ */ ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++#define for_each_entity(entity) \ ++ for (; entity ; entity = entity->parent) ++ ++#define for_each_entity_safe(entity, parent) \ ++ for (; entity && ({ parent = entity->parent; 1; }); entity = parent) ++ ++ ++static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, ++ int extract, ++ struct bfq_data *bfqd); ++ ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); ++ ++static void bfq_update_budget(struct bfq_entity *next_in_service) ++{ ++ struct bfq_entity *bfqg_entity; ++ struct bfq_group *bfqg; ++ struct bfq_sched_data *group_sd; ++ ++ BUG_ON(!next_in_service); ++ ++ group_sd = next_in_service->sched_data; ++ ++ bfqg = container_of(group_sd, struct bfq_group, sched_data); ++ /* ++ * bfq_group's my_entity field is not NULL only if the group ++ * is not the root group. We must not touch the root entity ++ * as it must never become an in-service entity. ++ */ ++ bfqg_entity = bfqg->my_entity; ++ if (bfqg_entity) ++ bfqg_entity->budget = next_in_service->budget; ++} ++ ++static int bfq_update_next_in_service(struct bfq_sched_data *sd) ++{ ++ struct bfq_entity *next_in_service; ++ ++ if (sd->in_service_entity) ++ /* will update/requeue at the end of service */ ++ return 0; ++ ++ /* ++ * NOTE: this can be improved in many ways, such as returning ++ * 1 (and thus propagating upwards the update) only when the ++ * budget changes, or caching the bfqq that will be scheduled ++ * next from this subtree. By now we worry more about ++ * correctness than about performance... ++ */ ++ next_in_service = bfq_lookup_next_entity(sd, 0, NULL); ++ sd->next_in_service = next_in_service; ++ ++ if (next_in_service) ++ bfq_update_budget(next_in_service); ++ ++ return 1; ++} ++ ++static void bfq_check_next_in_service(struct bfq_sched_data *sd, ++ struct bfq_entity *entity) ++{ ++ BUG_ON(sd->next_in_service != entity); ++} ++#else ++#define for_each_entity(entity) \ ++ for (; entity ; entity = NULL) ++ ++#define for_each_entity_safe(entity, parent) \ ++ for (parent = NULL; entity ; entity = parent) ++ ++static int bfq_update_next_in_service(struct bfq_sched_data *sd) ++{ ++ return 0; ++} ++ ++static void bfq_check_next_in_service(struct bfq_sched_data *sd, ++ struct bfq_entity *entity) ++{ ++} ++ ++static void bfq_update_budget(struct bfq_entity *next_in_service) ++{ ++} ++#endif ++ ++/* ++ * Shift for timestamp calculations. This actually limits the maximum ++ * service allowed in one timestamp delta (small shift values increase it), ++ * the maximum total weight that can be used for the queues in the system ++ * (big shift values increase it), and the period of virtual time ++ * wraparounds. ++ */ ++#define WFQ_SERVICE_SHIFT 22 ++ ++/** ++ * bfq_gt - compare two timestamps. ++ * @a: first ts. ++ * @b: second ts. ++ * ++ * Return @a > @b, dealing with wrapping correctly. ++ */ ++static int bfq_gt(u64 a, u64 b) ++{ ++ return (s64)(a - b) > 0; ++} ++ ++static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = NULL; ++ ++ BUG_ON(!entity); ++ ++ if (!entity->my_sched_data) ++ bfqq = container_of(entity, struct bfq_queue, entity); ++ ++ return bfqq; ++} ++ ++ ++/** ++ * bfq_delta - map service into the virtual time domain. ++ * @service: amount of service. ++ * @weight: scale factor (weight of an entity or weight sum). ++ */ ++static u64 bfq_delta(unsigned long service, unsigned long weight) ++{ ++ u64 d = (u64)service << WFQ_SERVICE_SHIFT; ++ ++ do_div(d, weight); ++ return d; ++} ++ ++/** ++ * bfq_calc_finish - assign the finish time to an entity. ++ * @entity: the entity to act upon. ++ * @service: the service to be charged to the entity. ++ */ ++static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ BUG_ON(entity->weight == 0); ++ ++ entity->finish = entity->start + ++ bfq_delta(service, entity->weight); ++ ++ if (bfqq) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "calc_finish: serv %lu, w %d", ++ service, entity->weight); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "calc_finish: start %llu, finish %llu, delta %llu", ++ entity->start, entity->finish, ++ bfq_delta(service, entity->weight)); ++ } ++} ++ ++/** ++ * bfq_entity_of - get an entity from a node. ++ * @node: the node field of the entity. ++ * ++ * Convert a node pointer to the relative entity. This is used only ++ * to simplify the logic of some functions and not as the generic ++ * conversion mechanism because, e.g., in the tree walking functions, ++ * the check for a %NULL value would be redundant. ++ */ ++static struct bfq_entity *bfq_entity_of(struct rb_node *node) ++{ ++ struct bfq_entity *entity = NULL; ++ ++ if (node) ++ entity = rb_entry(node, struct bfq_entity, rb_node); ++ ++ return entity; ++} ++ ++/** ++ * bfq_extract - remove an entity from a tree. ++ * @root: the tree root. ++ * @entity: the entity to remove. ++ */ ++static void bfq_extract(struct rb_root *root, struct bfq_entity *entity) ++{ ++ BUG_ON(entity->tree != root); ++ ++ entity->tree = NULL; ++ rb_erase(&entity->rb_node, root); ++} ++ ++/** ++ * bfq_idle_extract - extract an entity from the idle tree. ++ * @st: the service tree of the owning @entity. ++ * @entity: the entity being removed. ++ */ ++static void bfq_idle_extract(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *next; ++ ++ BUG_ON(entity->tree != &st->idle); ++ ++ if (entity == st->first_idle) { ++ next = rb_next(&entity->rb_node); ++ st->first_idle = bfq_entity_of(next); ++ } ++ ++ if (entity == st->last_idle) { ++ next = rb_prev(&entity->rb_node); ++ st->last_idle = bfq_entity_of(next); ++ } ++ ++ bfq_extract(&st->idle, entity); ++ ++ if (bfqq) ++ list_del(&bfqq->bfqq_list); ++} ++ ++/** ++ * bfq_insert - generic tree insertion. ++ * @root: tree root. ++ * @entity: entity to insert. ++ * ++ * This is used for the idle and the active tree, since they are both ++ * ordered by finish time. ++ */ ++static void bfq_insert(struct rb_root *root, struct bfq_entity *entity) ++{ ++ struct bfq_entity *entry; ++ struct rb_node **node = &root->rb_node; ++ struct rb_node *parent = NULL; ++ ++ BUG_ON(entity->tree); ++ ++ while (*node) { ++ parent = *node; ++ entry = rb_entry(parent, struct bfq_entity, rb_node); ++ ++ if (bfq_gt(entry->finish, entity->finish)) ++ node = &parent->rb_left; ++ else ++ node = &parent->rb_right; ++ } ++ ++ rb_link_node(&entity->rb_node, parent, node); ++ rb_insert_color(&entity->rb_node, root); ++ ++ entity->tree = root; ++} ++ ++/** ++ * bfq_update_min - update the min_start field of a entity. ++ * @entity: the entity to update. ++ * @node: one of its children. ++ * ++ * This function is called when @entity may store an invalid value for ++ * min_start due to updates to the active tree. The function assumes ++ * that the subtree rooted at @node (which may be its left or its right ++ * child) has a valid min_start value. ++ */ ++static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node) ++{ ++ struct bfq_entity *child; ++ ++ if (node) { ++ child = rb_entry(node, struct bfq_entity, rb_node); ++ if (bfq_gt(entity->min_start, child->min_start)) ++ entity->min_start = child->min_start; ++ } ++} ++ ++/** ++ * bfq_update_active_node - recalculate min_start. ++ * @node: the node to update. ++ * ++ * @node may have changed position or one of its children may have moved, ++ * this function updates its min_start value. The left and right subtrees ++ * are assumed to hold a correct min_start value. ++ */ ++static void bfq_update_active_node(struct rb_node *node) ++{ ++ struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node); ++ ++ entity->min_start = entity->start; ++ bfq_update_min(entity, node->rb_right); ++ bfq_update_min(entity, node->rb_left); ++} ++ ++/** ++ * bfq_update_active_tree - update min_start for the whole active tree. ++ * @node: the starting node. ++ * ++ * @node must be the deepest modified node after an update. This function ++ * updates its min_start using the values held by its children, assuming ++ * that they did not change, and then updates all the nodes that may have ++ * changed in the path to the root. The only nodes that may have changed ++ * are the ones in the path or their siblings. ++ */ ++static void bfq_update_active_tree(struct rb_node *node) ++{ ++ struct rb_node *parent; ++ ++up: ++ bfq_update_active_node(node); ++ ++ parent = rb_parent(node); ++ if (!parent) ++ return; ++ ++ if (node == parent->rb_left && parent->rb_right) ++ bfq_update_active_node(parent->rb_right); ++ else if (parent->rb_left) ++ bfq_update_active_node(parent->rb_left); ++ ++ node = parent; ++ goto up; ++} ++ ++static void bfq_weights_tree_add(struct bfq_data *bfqd, ++ struct bfq_entity *entity, ++ struct rb_root *root); ++ ++static void bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_entity *entity, ++ struct rb_root *root); ++ ++ ++/** ++ * bfq_active_insert - insert an entity in the active tree of its ++ * group/device. ++ * @st: the service tree of the entity. ++ * @entity: the entity being inserted. ++ * ++ * The active tree is ordered by finish time, but an extra key is kept ++ * per each node, containing the minimum value for the start times of ++ * its children (and the node itself), so it's possible to search for ++ * the eligible node with the lowest finish time in logarithmic time. ++ */ ++static void bfq_active_insert(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *node = &entity->rb_node; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ struct bfq_sched_data *sd = NULL; ++ struct bfq_group *bfqg = NULL; ++ struct bfq_data *bfqd = NULL; ++#endif ++ ++ bfq_insert(&st->active, entity); ++ ++ if (node->rb_left) ++ node = node->rb_left; ++ else if (node->rb_right) ++ node = node->rb_right; ++ ++ bfq_update_active_tree(node); ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ sd = entity->sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++#endif ++ if (bfqq) ++ list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { /* bfq_group */ ++ BUG_ON(!bfqd); ++ bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree); ++ } ++ if (bfqg != bfqd->root_group) { ++ BUG_ON(!bfqg); ++ BUG_ON(!bfqd); ++ bfqg->active_entities++; ++ if (bfqg->active_entities == 2) ++ bfqd->active_numerous_groups++; ++ } ++#endif ++} ++ ++/** ++ * bfq_ioprio_to_weight - calc a weight from an ioprio. ++ * @ioprio: the ioprio value to convert. ++ */ ++static unsigned short bfq_ioprio_to_weight(int ioprio) ++{ ++ BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR); ++ return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - ioprio; ++} ++ ++/** ++ * bfq_weight_to_ioprio - calc an ioprio from a weight. ++ * @weight: the weight value to convert. ++ * ++ * To preserve as much as possible the old only-ioprio user interface, ++ * 0 is used as an escape ioprio value for weights (numerically) equal or ++ * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF. ++ */ ++static unsigned short bfq_weight_to_ioprio(int weight) ++{ ++ BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT); ++ return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight < 0 ? ++ 0 : IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight; ++} ++ ++static void bfq_get_entity(struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ if (bfqq) { ++ atomic_inc(&bfqq->ref); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ } ++} ++ ++/** ++ * bfq_find_deepest - find the deepest node that an extraction can modify. ++ * @node: the node being removed. ++ * ++ * Do the first step of an extraction in an rb tree, looking for the ++ * node that will replace @node, and returning the deepest node that ++ * the following modifications to the tree can touch. If @node is the ++ * last node in the tree return %NULL. ++ */ ++static struct rb_node *bfq_find_deepest(struct rb_node *node) ++{ ++ struct rb_node *deepest; ++ ++ if (!node->rb_right && !node->rb_left) ++ deepest = rb_parent(node); ++ else if (!node->rb_right) ++ deepest = node->rb_left; ++ else if (!node->rb_left) ++ deepest = node->rb_right; ++ else { ++ deepest = rb_next(node); ++ if (deepest->rb_right) ++ deepest = deepest->rb_right; ++ else if (rb_parent(deepest) != node) ++ deepest = rb_parent(deepest); ++ } ++ ++ return deepest; ++} ++ ++/** ++ * bfq_active_extract - remove an entity from the active tree. ++ * @st: the service_tree containing the tree. ++ * @entity: the entity being removed. ++ */ ++static void bfq_active_extract(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *node; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ struct bfq_sched_data *sd = NULL; ++ struct bfq_group *bfqg = NULL; ++ struct bfq_data *bfqd = NULL; ++#endif ++ ++ node = bfq_find_deepest(&entity->rb_node); ++ bfq_extract(&st->active, entity); ++ ++ if (node) ++ bfq_update_active_tree(node); ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ sd = entity->sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++#endif ++ if (bfqq) ++ list_del(&bfqq->bfqq_list); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { /* bfq_group */ ++ BUG_ON(!bfqd); ++ bfq_weights_tree_remove(bfqd, entity, ++ &bfqd->group_weights_tree); ++ } ++ if (bfqg != bfqd->root_group) { ++ BUG_ON(!bfqg); ++ BUG_ON(!bfqd); ++ BUG_ON(!bfqg->active_entities); ++ bfqg->active_entities--; ++ if (bfqg->active_entities == 1) { ++ BUG_ON(!bfqd->active_numerous_groups); ++ bfqd->active_numerous_groups--; ++ } ++ } ++#endif ++} ++ ++/** ++ * bfq_idle_insert - insert an entity into the idle tree. ++ * @st: the service tree containing the tree. ++ * @entity: the entity to insert. ++ */ ++static void bfq_idle_insert(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct bfq_entity *first_idle = st->first_idle; ++ struct bfq_entity *last_idle = st->last_idle; ++ ++ if (!first_idle || bfq_gt(first_idle->finish, entity->finish)) ++ st->first_idle = entity; ++ if (!last_idle || bfq_gt(entity->finish, last_idle->finish)) ++ st->last_idle = entity; ++ ++ bfq_insert(&st->idle, entity); ++ ++ if (bfqq) ++ list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list); ++} ++ ++/** ++ * bfq_forget_entity - remove an entity from the wfq trees. ++ * @st: the service tree. ++ * @entity: the entity being removed. ++ * ++ * Update the device status and forget everything about @entity, putting ++ * the device reference to it, if it is a queue. Entities belonging to ++ * groups are not refcounted. ++ */ ++static void bfq_forget_entity(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct bfq_sched_data *sd; ++ ++ BUG_ON(!entity->on_st); ++ ++ entity->on_st = 0; ++ st->wsum -= entity->weight; ++ if (bfqq) { ++ sd = entity->sched_data; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ bfq_put_queue(bfqq); ++ } ++} ++ ++/** ++ * bfq_put_idle_entity - release the idle tree ref of an entity. ++ * @st: service tree for the entity. ++ * @entity: the entity being released. ++ */ ++static void bfq_put_idle_entity(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ bfq_idle_extract(st, entity); ++ bfq_forget_entity(st, entity); ++} ++ ++/** ++ * bfq_forget_idle - update the idle tree if necessary. ++ * @st: the service tree to act upon. ++ * ++ * To preserve the global O(log N) complexity we only remove one entry here; ++ * as the idle tree will not grow indefinitely this can be done safely. ++ */ ++static void bfq_forget_idle(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *first_idle = st->first_idle; ++ struct bfq_entity *last_idle = st->last_idle; ++ ++ if (RB_EMPTY_ROOT(&st->active) && last_idle && ++ !bfq_gt(last_idle->finish, st->vtime)) { ++ /* ++ * Forget the whole idle tree, increasing the vtime past ++ * the last finish time of idle entities. ++ */ ++ st->vtime = last_idle->finish; ++ } ++ ++ if (first_idle && !bfq_gt(first_idle->finish, st->vtime)) ++ bfq_put_idle_entity(st, first_idle); ++} ++ ++static struct bfq_service_tree * ++__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_service_tree *new_st = old_st; ++ ++ if (entity->prio_changed) { ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ unsigned short prev_weight, new_weight; ++ struct bfq_data *bfqd = NULL; ++ struct rb_root *root; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ struct bfq_sched_data *sd; ++ struct bfq_group *bfqg; ++#endif ++ ++ if (bfqq) ++ bfqd = bfqq->bfqd; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { ++ sd = entity->my_sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++ BUG_ON(!bfqd); ++ } ++#endif ++ ++ BUG_ON(old_st->wsum < entity->weight); ++ old_st->wsum -= entity->weight; ++ ++ if (entity->new_weight != entity->orig_weight) { ++ if (entity->new_weight < BFQ_MIN_WEIGHT || ++ entity->new_weight > BFQ_MAX_WEIGHT) { ++ printk(KERN_CRIT "update_weight_prio: " ++ "new_weight %d\n", ++ entity->new_weight); ++ BUG(); ++ } ++ entity->orig_weight = entity->new_weight; ++ if (bfqq) ++ bfqq->ioprio = ++ bfq_weight_to_ioprio(entity->orig_weight); ++ } ++ ++ if (bfqq) ++ bfqq->ioprio_class = bfqq->new_ioprio_class; ++ entity->prio_changed = 0; ++ ++ /* ++ * NOTE: here we may be changing the weight too early, ++ * this will cause unfairness. The correct approach ++ * would have required additional complexity to defer ++ * weight changes to the proper time instants (i.e., ++ * when entity->finish <= old_st->vtime). ++ */ ++ new_st = bfq_entity_service_tree(entity); ++ ++ prev_weight = entity->weight; ++ new_weight = entity->orig_weight * ++ (bfqq ? bfqq->wr_coeff : 1); ++ /* ++ * If the weight of the entity changes, remove the entity ++ * from its old weight counter (if there is a counter ++ * associated with the entity), and add it to the counter ++ * associated with its new weight. ++ */ ++ if (prev_weight != new_weight) { ++ root = bfqq ? &bfqd->queue_weights_tree : ++ &bfqd->group_weights_tree; ++ bfq_weights_tree_remove(bfqd, entity, root); ++ } ++ entity->weight = new_weight; ++ /* ++ * Add the entity to its weights tree only if it is ++ * not associated with a weight-raised queue. ++ */ ++ if (prev_weight != new_weight && ++ (bfqq ? bfqq->wr_coeff == 1 : 1)) ++ /* If we get here, root has been initialized. */ ++ bfq_weights_tree_add(bfqd, entity, root); ++ ++ new_st->wsum += entity->weight; ++ ++ if (new_st != old_st) ++ entity->start = new_st->vtime; ++ } ++ ++ return new_st; ++} ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg); ++#endif ++ ++/** ++ * bfq_bfqq_served - update the scheduler status after selection for ++ * service. ++ * @bfqq: the queue being served. ++ * @served: bytes to transfer. ++ * ++ * NOTE: this can be optimized, as the timestamps of upper level entities ++ * are synchronized every time a new bfqq is selected for service. By now, ++ * we keep it to better check consistency. ++ */ ++static void bfq_bfqq_served(struct bfq_queue *bfqq, int served) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_service_tree *st; ++ ++ for_each_entity(entity) { ++ st = bfq_entity_service_tree(entity); ++ ++ entity->service += served; ++ BUG_ON(entity->service > entity->budget); ++ BUG_ON(st->wsum == 0); ++ ++ st->vtime += bfq_delta(served, st->wsum); ++ bfq_forget_idle(st); ++ } ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_set_start_empty_time(bfqq_group(bfqq)); ++#endif ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served); ++} ++ ++/** ++ * bfq_bfqq_charge_full_budget - set the service to the entity budget. ++ * @bfqq: the queue that needs a service update. ++ * ++ * When it's not possible to be fair in the service domain, because ++ * a queue is not consuming its budget fast enough (the meaning of ++ * fast depends on the timeout parameter), we charge it a full ++ * budget. In this way we should obtain a sort of time-domain ++ * fairness among all the seeky/slow queues. ++ */ ++static void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget"); ++ ++ bfq_bfqq_served(bfqq, entity->budget - entity->service); ++} ++ ++/** ++ * __bfq_activate_entity - activate an entity. ++ * @entity: the entity being activated. ++ * ++ * Called whenever an entity is activated, i.e., it is not active and one ++ * of its children receives a new request, or has to be reactivated due to ++ * budget exhaustion. It uses the current budget of the entity (and the ++ * service received if @entity is active) of the queue to calculate its ++ * timestamps. ++ */ ++static void __bfq_activate_entity(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sd = entity->sched_data; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ ++ if (entity == sd->in_service_entity) { ++ BUG_ON(entity->tree); ++ /* ++ * If we are requeueing the current entity we have ++ * to take care of not charging to it service it has ++ * not received. ++ */ ++ bfq_calc_finish(entity, entity->service); ++ entity->start = entity->finish; ++ sd->in_service_entity = NULL; ++ } else if (entity->tree == &st->active) { ++ /* ++ * Requeueing an entity due to a change of some ++ * next_in_service entity below it. We reuse the ++ * old start time. ++ */ ++ bfq_active_extract(st, entity); ++ } else if (entity->tree == &st->idle) { ++ /* ++ * Must be on the idle tree, bfq_idle_extract() will ++ * check for that. ++ */ ++ bfq_idle_extract(st, entity); ++ entity->start = bfq_gt(st->vtime, entity->finish) ? ++ st->vtime : entity->finish; ++ } else { ++ /* ++ * The finish time of the entity may be invalid, and ++ * it is in the past for sure, otherwise the queue ++ * would have been on the idle tree. ++ */ ++ entity->start = st->vtime; ++ st->wsum += entity->weight; ++ bfq_get_entity(entity); ++ ++ BUG_ON(entity->on_st); ++ entity->on_st = 1; ++ } ++ ++ st = __bfq_entity_update_weight_prio(st, entity); ++ bfq_calc_finish(entity, entity->budget); ++ bfq_active_insert(st, entity); ++} ++ ++/** ++ * bfq_activate_entity - activate an entity and its ancestors if necessary. ++ * @entity: the entity to activate. ++ * ++ * Activate @entity and all the entities on the path from it to the root. ++ */ ++static void bfq_activate_entity(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sd; ++ ++ for_each_entity(entity) { ++ __bfq_activate_entity(entity); ++ ++ sd = entity->sched_data; ++ if (!bfq_update_next_in_service(sd)) ++ /* ++ * No need to propagate the activation to the ++ * upper entities, as they will be updated when ++ * the in-service entity is rescheduled. ++ */ ++ break; ++ } ++} ++ ++/** ++ * __bfq_deactivate_entity - deactivate an entity from its service tree. ++ * @entity: the entity to deactivate. ++ * @requeue: if false, the entity will not be put into the idle tree. ++ * ++ * Deactivate an entity, independently from its previous state. If the ++ * entity was not on a service tree just return, otherwise if it is on ++ * any scheduler tree, extract it from that tree, and if necessary ++ * and if the caller did not specify @requeue, put it on the idle tree. ++ * ++ * Return %1 if the caller should update the entity hierarchy, i.e., ++ * if the entity was in service or if it was the next_in_service for ++ * its sched_data; return %0 otherwise. ++ */ ++static int __bfq_deactivate_entity(struct bfq_entity *entity, int requeue) ++{ ++ struct bfq_sched_data *sd = entity->sched_data; ++ struct bfq_service_tree *st; ++ int was_in_service; ++ int ret = 0; ++ ++ if (sd == NULL || !entity->on_st) /* never activated, or inactive */ ++ return 0; ++ ++ st = bfq_entity_service_tree(entity); ++ was_in_service = entity == sd->in_service_entity; ++ ++ BUG_ON(was_in_service && entity->tree); ++ ++ if (was_in_service) { ++ bfq_calc_finish(entity, entity->service); ++ sd->in_service_entity = NULL; ++ } else if (entity->tree == &st->active) ++ bfq_active_extract(st, entity); ++ else if (entity->tree == &st->idle) ++ bfq_idle_extract(st, entity); ++ else if (entity->tree) ++ BUG(); ++ ++ if (was_in_service || sd->next_in_service == entity) ++ ret = bfq_update_next_in_service(sd); ++ ++ if (!requeue || !bfq_gt(entity->finish, st->vtime)) ++ bfq_forget_entity(st, entity); ++ else ++ bfq_idle_insert(st, entity); ++ ++ BUG_ON(sd->in_service_entity == entity); ++ BUG_ON(sd->next_in_service == entity); ++ ++ return ret; ++} ++ ++/** ++ * bfq_deactivate_entity - deactivate an entity. ++ * @entity: the entity to deactivate. ++ * @requeue: true if the entity can be put on the idle tree ++ */ ++static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue) ++{ ++ struct bfq_sched_data *sd; ++ struct bfq_entity *parent; ++ ++ for_each_entity_safe(entity, parent) { ++ sd = entity->sched_data; ++ ++ if (!__bfq_deactivate_entity(entity, requeue)) ++ /* ++ * The parent entity is still backlogged, and ++ * we don't need to update it as it is still ++ * in service. ++ */ ++ break; ++ ++ if (sd->next_in_service) ++ /* ++ * The parent entity is still backlogged and ++ * the budgets on the path towards the root ++ * need to be updated. ++ */ ++ goto update; ++ ++ /* ++ * If we reach there the parent is no more backlogged and ++ * we want to propagate the dequeue upwards. ++ */ ++ requeue = 1; ++ } ++ ++ return; ++ ++update: ++ entity = parent; ++ for_each_entity(entity) { ++ __bfq_activate_entity(entity); ++ ++ sd = entity->sched_data; ++ if (!bfq_update_next_in_service(sd)) ++ break; ++ } ++} ++ ++/** ++ * bfq_update_vtime - update vtime if necessary. ++ * @st: the service tree to act upon. ++ * ++ * If necessary update the service tree vtime to have at least one ++ * eligible entity, skipping to its start time. Assumes that the ++ * active tree of the device is not empty. ++ * ++ * NOTE: this hierarchical implementation updates vtimes quite often, ++ * we may end up with reactivated processes getting timestamps after a ++ * vtime skip done because we needed a ->first_active entity on some ++ * intermediate node. ++ */ ++static void bfq_update_vtime(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *entry; ++ struct rb_node *node = st->active.rb_node; ++ ++ entry = rb_entry(node, struct bfq_entity, rb_node); ++ if (bfq_gt(entry->min_start, st->vtime)) { ++ st->vtime = entry->min_start; ++ bfq_forget_idle(st); ++ } ++} ++ ++/** ++ * bfq_first_active_entity - find the eligible entity with ++ * the smallest finish time ++ * @st: the service tree to select from. ++ * ++ * This function searches the first schedulable entity, starting from the ++ * root of the tree and going on the left every time on this side there is ++ * a subtree with at least one eligible (start >= vtime) entity. The path on ++ * the right is followed only if a) the left subtree contains no eligible ++ * entities and b) no eligible entity has been found yet. ++ */ ++static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *entry, *first = NULL; ++ struct rb_node *node = st->active.rb_node; ++ ++ while (node) { ++ entry = rb_entry(node, struct bfq_entity, rb_node); ++left: ++ if (!bfq_gt(entry->start, st->vtime)) ++ first = entry; ++ ++ BUG_ON(bfq_gt(entry->min_start, st->vtime)); ++ ++ if (node->rb_left) { ++ entry = rb_entry(node->rb_left, ++ struct bfq_entity, rb_node); ++ if (!bfq_gt(entry->min_start, st->vtime)) { ++ node = node->rb_left; ++ goto left; ++ } ++ } ++ if (first) ++ break; ++ node = node->rb_right; ++ } ++ ++ BUG_ON(!first && !RB_EMPTY_ROOT(&st->active)); ++ return first; ++} ++ ++/** ++ * __bfq_lookup_next_entity - return the first eligible entity in @st. ++ * @st: the service tree. ++ * ++ * Update the virtual time in @st and return the first eligible entity ++ * it contains. ++ */ ++static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st, ++ bool force) ++{ ++ struct bfq_entity *entity, *new_next_in_service = NULL; ++ ++ if (RB_EMPTY_ROOT(&st->active)) ++ return NULL; ++ ++ bfq_update_vtime(st); ++ entity = bfq_first_active_entity(st); ++ BUG_ON(bfq_gt(entity->start, st->vtime)); ++ ++ /* ++ * If the chosen entity does not match with the sched_data's ++ * next_in_service and we are forcedly serving the IDLE priority ++ * class tree, bubble up budget update. ++ */ ++ if (unlikely(force && entity != entity->sched_data->next_in_service)) { ++ new_next_in_service = entity; ++ for_each_entity(new_next_in_service) ++ bfq_update_budget(new_next_in_service); ++ } ++ ++ return entity; ++} ++ ++/** ++ * bfq_lookup_next_entity - return the first eligible entity in @sd. ++ * @sd: the sched_data. ++ * @extract: if true the returned entity will be also extracted from @sd. ++ * ++ * NOTE: since we cache the next_in_service entity at each level of the ++ * hierarchy, the complexity of the lookup can be decreased with ++ * absolutely no effort just returning the cached next_in_service value; ++ * we prefer to do full lookups to test the consistency of * the data ++ * structures. ++ */ ++static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, ++ int extract, ++ struct bfq_data *bfqd) ++{ ++ struct bfq_service_tree *st = sd->service_tree; ++ struct bfq_entity *entity; ++ int i = 0; ++ ++ BUG_ON(sd->in_service_entity); ++ ++ if (bfqd && ++ jiffies - bfqd->bfq_class_idle_last_service > BFQ_CL_IDLE_TIMEOUT) { ++ entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1, ++ true); ++ if (entity) { ++ i = BFQ_IOPRIO_CLASSES - 1; ++ bfqd->bfq_class_idle_last_service = jiffies; ++ sd->next_in_service = entity; ++ } ++ } ++ for (; i < BFQ_IOPRIO_CLASSES; i++) { ++ entity = __bfq_lookup_next_entity(st + i, false); ++ if (entity) { ++ if (extract) { ++ bfq_check_next_in_service(sd, entity); ++ bfq_active_extract(st + i, entity); ++ sd->in_service_entity = entity; ++ sd->next_in_service = NULL; ++ } ++ break; ++ } ++ } ++ ++ return entity; ++} ++ ++/* ++ * Get next queue for service. ++ */ ++static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_entity *entity = NULL; ++ struct bfq_sched_data *sd; ++ struct bfq_queue *bfqq; ++ ++ BUG_ON(bfqd->in_service_queue); ++ ++ if (bfqd->busy_queues == 0) ++ return NULL; ++ ++ sd = &bfqd->root_group->sched_data; ++ for (; sd ; sd = entity->my_sched_data) { ++ entity = bfq_lookup_next_entity(sd, 1, bfqd); ++ BUG_ON(!entity); ++ entity->service = 0; ++ } ++ ++ bfqq = bfq_entity_to_bfqq(entity); ++ BUG_ON(!bfqq); ++ ++ return bfqq; ++} ++ ++static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd) ++{ ++ if (bfqd->in_service_bic) { ++ put_io_context(bfqd->in_service_bic->icq.ioc); ++ bfqd->in_service_bic = NULL; ++ } ++ ++ bfqd->in_service_queue = NULL; ++ del_timer(&bfqd->idle_slice_timer); ++} ++ ++static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ int requeue) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (bfqq == bfqd->in_service_queue) ++ __bfq_bfqd_reset_in_service(bfqd); ++ ++ bfq_deactivate_entity(entity, requeue); ++} ++ ++static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ bfq_activate_entity(entity); ++} ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++static void bfqg_stats_update_dequeue(struct bfq_group *bfqg); ++#endif ++ ++/* ++ * Called when the bfqq no longer has requests pending, remove it from ++ * the service tree. ++ */ ++static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ int requeue) ++{ ++ BUG_ON(!bfq_bfqq_busy(bfqq)); ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ bfq_log_bfqq(bfqd, bfqq, "del from busy"); ++ ++ bfq_clear_bfqq_busy(bfqq); ++ ++ BUG_ON(bfqd->busy_queues == 0); ++ bfqd->busy_queues--; ++ ++ if (!bfqq->dispatched) { ++ bfq_weights_tree_remove(bfqd, &bfqq->entity, ++ &bfqd->queue_weights_tree); ++ if (!blk_queue_nonrot(bfqd->queue)) { ++ BUG_ON(!bfqd->busy_in_flight_queues); ++ bfqd->busy_in_flight_queues--; ++ if (bfq_bfqq_constantly_seeky(bfqq)) { ++ BUG_ON(!bfqd-> ++ const_seeky_busy_in_flight_queues); ++ bfqd->const_seeky_busy_in_flight_queues--; ++ } ++ } ++ } ++ if (bfqq->wr_coeff > 1) ++ bfqd->wr_busy_queues--; ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ bfqg_stats_update_dequeue(bfqq_group(bfqq)); ++#endif ++ ++ bfq_deactivate_bfqq(bfqd, bfqq, requeue); ++} ++ ++/* ++ * Called when an inactive queue receives a new request. ++ */ ++static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ BUG_ON(bfq_bfqq_busy(bfqq)); ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ ++ bfq_log_bfqq(bfqd, bfqq, "add to busy"); ++ ++ bfq_activate_bfqq(bfqd, bfqq); ++ ++ bfq_mark_bfqq_busy(bfqq); ++ bfqd->busy_queues++; ++ ++ if (!bfqq->dispatched) { ++ if (bfqq->wr_coeff == 1) ++ bfq_weights_tree_add(bfqd, &bfqq->entity, ++ &bfqd->queue_weights_tree); ++ if (!blk_queue_nonrot(bfqd->queue)) { ++ bfqd->busy_in_flight_queues++; ++ if (bfq_bfqq_constantly_seeky(bfqq)) ++ bfqd->const_seeky_busy_in_flight_queues++; ++ } ++ } ++ if (bfqq->wr_coeff > 1) ++ bfqd->wr_busy_queues++; ++} +diff --git a/block/bfq.h b/block/bfq.h +new file mode 100644 +index 0000000..485d0c9 +--- /dev/null ++++ b/block/bfq.h +@@ -0,0 +1,801 @@ ++/* ++ * BFQ-v7r11 for 4.5.0: data structures and common functions prototypes. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ */ ++ ++#ifndef _BFQ_H ++#define _BFQ_H ++ ++#include ++#include ++#include ++#include ++#include ++ ++#define BFQ_IOPRIO_CLASSES 3 ++#define BFQ_CL_IDLE_TIMEOUT (HZ/5) ++ ++#define BFQ_MIN_WEIGHT 1 ++#define BFQ_MAX_WEIGHT 1000 ++#define BFQ_WEIGHT_CONVERSION_COEFF 10 ++ ++#define BFQ_DEFAULT_QUEUE_IOPRIO 4 ++ ++#define BFQ_DEFAULT_GRP_WEIGHT 10 ++#define BFQ_DEFAULT_GRP_IOPRIO 0 ++#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE ++ ++struct bfq_entity; ++ ++/** ++ * struct bfq_service_tree - per ioprio_class service tree. ++ * @active: tree for active entities (i.e., those backlogged). ++ * @idle: tree for idle entities (i.e., those not backlogged, with V <= F_i). ++ * @first_idle: idle entity with minimum F_i. ++ * @last_idle: idle entity with maximum F_i. ++ * @vtime: scheduler virtual time. ++ * @wsum: scheduler weight sum; active and idle entities contribute to it. ++ * ++ * Each service tree represents a B-WF2Q+ scheduler on its own. Each ++ * ioprio_class has its own independent scheduler, and so its own ++ * bfq_service_tree. All the fields are protected by the queue lock ++ * of the containing bfqd. ++ */ ++struct bfq_service_tree { ++ struct rb_root active; ++ struct rb_root idle; ++ ++ struct bfq_entity *first_idle; ++ struct bfq_entity *last_idle; ++ ++ u64 vtime; ++ unsigned long wsum; ++}; ++ ++/** ++ * struct bfq_sched_data - multi-class scheduler. ++ * @in_service_entity: entity in service. ++ * @next_in_service: head-of-the-line entity in the scheduler. ++ * @service_tree: array of service trees, one per ioprio_class. ++ * ++ * bfq_sched_data is the basic scheduler queue. It supports three ++ * ioprio_classes, and can be used either as a toplevel queue or as ++ * an intermediate queue on a hierarchical setup. ++ * @next_in_service points to the active entity of the sched_data ++ * service trees that will be scheduled next. ++ * ++ * The supported ioprio_classes are the same as in CFQ, in descending ++ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. ++ * Requests from higher priority queues are served before all the ++ * requests from lower priority queues; among requests of the same ++ * queue requests are served according to B-WF2Q+. ++ * All the fields are protected by the queue lock of the containing bfqd. ++ */ ++struct bfq_sched_data { ++ struct bfq_entity *in_service_entity; ++ struct bfq_entity *next_in_service; ++ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; ++}; ++ ++/** ++ * struct bfq_weight_counter - counter of the number of all active entities ++ * with a given weight. ++ * @weight: weight of the entities that this counter refers to. ++ * @num_active: number of active entities with this weight. ++ * @weights_node: weights tree member (see bfq_data's @queue_weights_tree ++ * and @group_weights_tree). ++ */ ++struct bfq_weight_counter { ++ short int weight; ++ unsigned int num_active; ++ struct rb_node weights_node; ++}; ++ ++/** ++ * struct bfq_entity - schedulable entity. ++ * @rb_node: service_tree member. ++ * @weight_counter: pointer to the weight counter associated with this entity. ++ * @on_st: flag, true if the entity is on a tree (either the active or ++ * the idle one of its service_tree). ++ * @finish: B-WF2Q+ finish timestamp (aka F_i). ++ * @start: B-WF2Q+ start timestamp (aka S_i). ++ * @tree: tree the entity is enqueued into; %NULL if not on a tree. ++ * @min_start: minimum start time of the (active) subtree rooted at ++ * this entity; used for O(log N) lookups into active trees. ++ * @service: service received during the last round of service. ++ * @budget: budget used to calculate F_i; F_i = S_i + @budget / @weight. ++ * @weight: weight of the queue ++ * @parent: parent entity, for hierarchical scheduling. ++ * @my_sched_data: for non-leaf nodes in the cgroup hierarchy, the ++ * associated scheduler queue, %NULL on leaf nodes. ++ * @sched_data: the scheduler queue this entity belongs to. ++ * @ioprio: the ioprio in use. ++ * @new_weight: when a weight change is requested, the new weight value. ++ * @orig_weight: original weight, used to implement weight boosting ++ * @prio_changed: flag, true when the user requested a weight, ioprio or ++ * ioprio_class change. ++ * ++ * A bfq_entity is used to represent either a bfq_queue (leaf node in the ++ * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each ++ * entity belongs to the sched_data of the parent group in the cgroup ++ * hierarchy. Non-leaf entities have also their own sched_data, stored ++ * in @my_sched_data. ++ * ++ * Each entity stores independently its priority values; this would ++ * allow different weights on different devices, but this ++ * functionality is not exported to userspace by now. Priorities and ++ * weights are updated lazily, first storing the new values into the ++ * new_* fields, then setting the @prio_changed flag. As soon as ++ * there is a transition in the entity state that allows the priority ++ * update to take place the effective and the requested priority ++ * values are synchronized. ++ * ++ * Unless cgroups are used, the weight value is calculated from the ++ * ioprio to export the same interface as CFQ. When dealing with ++ * ``well-behaved'' queues (i.e., queues that do not spend too much ++ * time to consume their budget and have true sequential behavior, and ++ * when there are no external factors breaking anticipation) the ++ * relative weights at each level of the cgroups hierarchy should be ++ * guaranteed. All the fields are protected by the queue lock of the ++ * containing bfqd. ++ */ ++struct bfq_entity { ++ struct rb_node rb_node; ++ struct bfq_weight_counter *weight_counter; ++ ++ int on_st; ++ ++ u64 finish; ++ u64 start; ++ ++ struct rb_root *tree; ++ ++ u64 min_start; ++ ++ int service, budget; ++ unsigned short weight, new_weight; ++ unsigned short orig_weight; ++ ++ struct bfq_entity *parent; ++ ++ struct bfq_sched_data *my_sched_data; ++ struct bfq_sched_data *sched_data; ++ ++ int prio_changed; ++}; ++ ++struct bfq_group; ++ ++/** ++ * struct bfq_queue - leaf schedulable entity. ++ * @ref: reference counter. ++ * @bfqd: parent bfq_data. ++ * @new_ioprio: when an ioprio change is requested, the new ioprio value. ++ * @ioprio_class: the ioprio_class in use. ++ * @new_ioprio_class: when an ioprio_class change is requested, the new ++ * ioprio_class value. ++ * @new_bfqq: shared bfq_queue if queue is cooperating with ++ * one or more other queues. ++ * @sort_list: sorted list of pending requests. ++ * @next_rq: if fifo isn't expired, next request to serve. ++ * @queued: nr of requests queued in @sort_list. ++ * @allocated: currently allocated requests. ++ * @meta_pending: pending metadata requests. ++ * @fifo: fifo list of requests in sort_list. ++ * @entity: entity representing this queue in the scheduler. ++ * @max_budget: maximum budget allowed from the feedback mechanism. ++ * @budget_timeout: budget expiration (in jiffies). ++ * @dispatched: number of requests on the dispatch list or inside driver. ++ * @flags: status flags. ++ * @bfqq_list: node for active/idle bfqq list inside our bfqd. ++ * @burst_list_node: node for the device's burst list. ++ * @seek_samples: number of seeks sampled ++ * @seek_total: sum of the distances of the seeks sampled ++ * @seek_mean: mean seek distance ++ * @last_request_pos: position of the last request enqueued ++ * @requests_within_timer: number of consecutive pairs of request completion ++ * and arrival, such that the queue becomes idle ++ * after the completion, but the next request arrives ++ * within an idle time slice; used only if the queue's ++ * IO_bound has been cleared. ++ * @pid: pid of the process owning the queue, used for logging purposes. ++ * @last_wr_start_finish: start time of the current weight-raising period if ++ * the @bfq-queue is being weight-raised, otherwise ++ * finish time of the last weight-raising period ++ * @wr_cur_max_time: current max raising time for this queue ++ * @soft_rt_next_start: minimum time instant such that, only if a new ++ * request is enqueued after this time instant in an ++ * idle @bfq_queue with no outstanding requests, then ++ * the task associated with the queue it is deemed as ++ * soft real-time (see the comments to the function ++ * bfq_bfqq_softrt_next_start()) ++ * @last_idle_bklogged: time of the last transition of the @bfq_queue from ++ * idle to backlogged ++ * @service_from_backlogged: cumulative service received from the @bfq_queue ++ * since the last transition from idle to ++ * backlogged ++ * @bic: pointer to the bfq_io_cq owning the bfq_queue, set to %NULL if the ++ * queue is shared ++ * ++ * A bfq_queue is a leaf request queue; it can be associated with an ++ * io_context or more, if it is async or shared between cooperating ++ * processes. @cgroup holds a reference to the cgroup, to be sure that it ++ * does not disappear while a bfqq still references it (mostly to avoid ++ * races between request issuing and task migration followed by cgroup ++ * destruction). ++ * All the fields are protected by the queue lock of the containing bfqd. ++ */ ++struct bfq_queue { ++ atomic_t ref; ++ struct bfq_data *bfqd; ++ ++ unsigned short ioprio, new_ioprio; ++ unsigned short ioprio_class, new_ioprio_class; ++ ++ /* fields for cooperating queues handling */ ++ struct bfq_queue *new_bfqq; ++ struct rb_node pos_node; ++ struct rb_root *pos_root; ++ ++ struct rb_root sort_list; ++ struct request *next_rq; ++ int queued[2]; ++ int allocated[2]; ++ int meta_pending; ++ struct list_head fifo; ++ ++ struct bfq_entity entity; ++ ++ int max_budget; ++ unsigned long budget_timeout; ++ ++ int dispatched; ++ ++ unsigned int flags; ++ ++ struct list_head bfqq_list; ++ ++ struct hlist_node burst_list_node; ++ ++ unsigned int seek_samples; ++ u64 seek_total; ++ sector_t seek_mean; ++ sector_t last_request_pos; ++ ++ unsigned int requests_within_timer; ++ ++ pid_t pid; ++ struct bfq_io_cq *bic; ++ ++ /* weight-raising fields */ ++ unsigned long wr_cur_max_time; ++ unsigned long soft_rt_next_start; ++ unsigned long last_wr_start_finish; ++ unsigned int wr_coeff; ++ unsigned long last_idle_bklogged; ++ unsigned long service_from_backlogged; ++}; ++ ++/** ++ * struct bfq_ttime - per process thinktime stats. ++ * @ttime_total: total process thinktime ++ * @ttime_samples: number of thinktime samples ++ * @ttime_mean: average process thinktime ++ */ ++struct bfq_ttime { ++ unsigned long last_end_request; ++ ++ unsigned long ttime_total; ++ unsigned long ttime_samples; ++ unsigned long ttime_mean; ++}; ++ ++/** ++ * struct bfq_io_cq - per (request_queue, io_context) structure. ++ * @icq: associated io_cq structure ++ * @bfqq: array of two process queues, the sync and the async ++ * @ttime: associated @bfq_ttime struct ++ * @ioprio: per (request_queue, blkcg) ioprio. ++ * @blkcg_id: id of the blkcg the related io_cq belongs to. ++ */ ++struct bfq_io_cq { ++ struct io_cq icq; /* must be the first member */ ++ struct bfq_queue *bfqq[2]; ++ struct bfq_ttime ttime; ++ int ioprio; ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ uint64_t blkcg_id; /* the current blkcg ID */ ++#endif ++}; ++ ++enum bfq_device_speed { ++ BFQ_BFQD_FAST, ++ BFQ_BFQD_SLOW, ++}; ++ ++/** ++ * struct bfq_data - per device data structure. ++ * @queue: request queue for the managed device. ++ * @root_group: root bfq_group for the device. ++ * @active_numerous_groups: number of bfq_groups containing more than one ++ * active @bfq_entity. ++ * @queue_weights_tree: rbtree of weight counters of @bfq_queues, sorted by ++ * weight. Used to keep track of whether all @bfq_queues ++ * have the same weight. The tree contains one counter ++ * for each distinct weight associated to some active ++ * and not weight-raised @bfq_queue (see the comments to ++ * the functions bfq_weights_tree_[add|remove] for ++ * further details). ++ * @group_weights_tree: rbtree of non-queue @bfq_entity weight counters, sorted ++ * by weight. Used to keep track of whether all ++ * @bfq_groups have the same weight. The tree contains ++ * one counter for each distinct weight associated to ++ * some active @bfq_group (see the comments to the ++ * functions bfq_weights_tree_[add|remove] for further ++ * details). ++ * @busy_queues: number of bfq_queues containing requests (including the ++ * queue in service, even if it is idling). ++ * @busy_in_flight_queues: number of @bfq_queues containing pending or ++ * in-flight requests, plus the @bfq_queue in ++ * service, even if idle but waiting for the ++ * possible arrival of its next sync request. This ++ * field is updated only if the device is rotational, ++ * but used only if the device is also NCQ-capable. ++ * The reason why the field is updated also for non- ++ * NCQ-capable rotational devices is related to the ++ * fact that the value of @hw_tag may be set also ++ * later than when busy_in_flight_queues may need to ++ * be incremented for the first time(s). Taking also ++ * this possibility into account, to avoid unbalanced ++ * increments/decrements, would imply more overhead ++ * than just updating busy_in_flight_queues ++ * regardless of the value of @hw_tag. ++ * @const_seeky_busy_in_flight_queues: number of constantly-seeky @bfq_queues ++ * (that is, seeky queues that expired ++ * for budget timeout at least once) ++ * containing pending or in-flight ++ * requests, including the in-service ++ * @bfq_queue if constantly seeky. This ++ * field is updated only if the device ++ * is rotational, but used only if the ++ * device is also NCQ-capable (see the ++ * comments to @busy_in_flight_queues). ++ * @wr_busy_queues: number of weight-raised busy @bfq_queues. ++ * @queued: number of queued requests. ++ * @rq_in_driver: number of requests dispatched and waiting for completion. ++ * @sync_flight: number of sync requests in the driver. ++ * @max_rq_in_driver: max number of reqs in driver in the last ++ * @hw_tag_samples completed requests. ++ * @hw_tag_samples: nr of samples used to calculate hw_tag. ++ * @hw_tag: flag set to one if the driver is showing a queueing behavior. ++ * @budgets_assigned: number of budgets assigned. ++ * @idle_slice_timer: timer set when idling for the next sequential request ++ * from the queue in service. ++ * @unplug_work: delayed work to restart dispatching on the request queue. ++ * @in_service_queue: bfq_queue in service. ++ * @in_service_bic: bfq_io_cq (bic) associated with the @in_service_queue. ++ * @last_position: on-disk position of the last served request. ++ * @last_budget_start: beginning of the last budget. ++ * @last_idling_start: beginning of the last idle slice. ++ * @peak_rate: peak transfer rate observed for a budget. ++ * @peak_rate_samples: number of samples used to calculate @peak_rate. ++ * @bfq_max_budget: maximum budget allotted to a bfq_queue before ++ * rescheduling. ++ * @active_list: list of all the bfq_queues active on the device. ++ * @idle_list: list of all the bfq_queues idle on the device. ++ * @bfq_fifo_expire: timeout for async/sync requests; when it expires ++ * requests are served in fifo order. ++ * @bfq_back_penalty: weight of backward seeks wrt forward ones. ++ * @bfq_back_max: maximum allowed backward seek. ++ * @bfq_slice_idle: maximum idling time. ++ * @bfq_user_max_budget: user-configured max budget value ++ * (0 for auto-tuning). ++ * @bfq_max_budget_async_rq: maximum budget (in nr of requests) allotted to ++ * async queues. ++ * @bfq_timeout: timeout for bfq_queues to consume their budget; used to ++ * to prevent seeky queues to impose long latencies to well ++ * behaved ones (this also implies that seeky queues cannot ++ * receive guarantees in the service domain; after a timeout ++ * they are charged for the whole allocated budget, to try ++ * to preserve a behavior reasonably fair among them, but ++ * without service-domain guarantees). ++ * @bfq_coop_thresh: number of queue merges after which a @bfq_queue is ++ * no more granted any weight-raising. ++ * @bfq_failed_cooperations: number of consecutive failed cooperation ++ * chances after which weight-raising is restored ++ * to a queue subject to more than bfq_coop_thresh ++ * queue merges. ++ * @bfq_requests_within_timer: number of consecutive requests that must be ++ * issued within the idle time slice to set ++ * again idling to a queue which was marked as ++ * non-I/O-bound (see the definition of the ++ * IO_bound flag for further details). ++ * @last_ins_in_burst: last time at which a queue entered the current ++ * burst of queues being activated shortly after ++ * each other; for more details about this and the ++ * following parameters related to a burst of ++ * activations, see the comments to the function ++ * @bfq_handle_burst. ++ * @bfq_burst_interval: reference time interval used to decide whether a ++ * queue has been activated shortly after ++ * @last_ins_in_burst. ++ * @burst_size: number of queues in the current burst of queue activations. ++ * @bfq_large_burst_thresh: maximum burst size above which the current ++ * queue-activation burst is deemed as 'large'. ++ * @large_burst: true if a large queue-activation burst is in progress. ++ * @burst_list: head of the burst list (as for the above fields, more details ++ * in the comments to the function bfq_handle_burst). ++ * @low_latency: if set to true, low-latency heuristics are enabled. ++ * @bfq_wr_coeff: maximum factor by which the weight of a weight-raised ++ * queue is multiplied. ++ * @bfq_wr_max_time: maximum duration of a weight-raising period (jiffies). ++ * @bfq_wr_rt_max_time: maximum duration for soft real-time processes. ++ * @bfq_wr_min_idle_time: minimum idle period after which weight-raising ++ * may be reactivated for a queue (in jiffies). ++ * @bfq_wr_min_inter_arr_async: minimum period between request arrivals ++ * after which weight-raising may be ++ * reactivated for an already busy queue ++ * (in jiffies). ++ * @bfq_wr_max_softrt_rate: max service-rate for a soft real-time queue, ++ * sectors per seconds. ++ * @RT_prod: cached value of the product R*T used for computing the maximum ++ * duration of the weight raising automatically. ++ * @device_speed: device-speed class for the low-latency heuristic. ++ * @oom_bfqq: fallback dummy bfqq for extreme OOM conditions. ++ * ++ * All the fields are protected by the @queue lock. ++ */ ++struct bfq_data { ++ struct request_queue *queue; ++ ++ struct bfq_group *root_group; ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ int active_numerous_groups; ++#endif ++ ++ struct rb_root queue_weights_tree; ++ struct rb_root group_weights_tree; ++ ++ int busy_queues; ++ int busy_in_flight_queues; ++ int const_seeky_busy_in_flight_queues; ++ int wr_busy_queues; ++ int queued; ++ int rq_in_driver; ++ int sync_flight; ++ ++ int max_rq_in_driver; ++ int hw_tag_samples; ++ int hw_tag; ++ ++ int budgets_assigned; ++ ++ struct timer_list idle_slice_timer; ++ struct work_struct unplug_work; ++ ++ struct bfq_queue *in_service_queue; ++ struct bfq_io_cq *in_service_bic; ++ ++ sector_t last_position; ++ ++ ktime_t last_budget_start; ++ ktime_t last_idling_start; ++ int peak_rate_samples; ++ u64 peak_rate; ++ int bfq_max_budget; ++ ++ struct list_head active_list; ++ struct list_head idle_list; ++ ++ unsigned int bfq_fifo_expire[2]; ++ unsigned int bfq_back_penalty; ++ unsigned int bfq_back_max; ++ unsigned int bfq_slice_idle; ++ u64 bfq_class_idle_last_service; ++ ++ int bfq_user_max_budget; ++ int bfq_max_budget_async_rq; ++ unsigned int bfq_timeout[2]; ++ ++ unsigned int bfq_coop_thresh; ++ unsigned int bfq_failed_cooperations; ++ unsigned int bfq_requests_within_timer; ++ ++ unsigned long last_ins_in_burst; ++ unsigned long bfq_burst_interval; ++ int burst_size; ++ unsigned long bfq_large_burst_thresh; ++ bool large_burst; ++ struct hlist_head burst_list; ++ ++ bool low_latency; ++ ++ /* parameters of the low_latency heuristics */ ++ unsigned int bfq_wr_coeff; ++ unsigned int bfq_wr_max_time; ++ unsigned int bfq_wr_rt_max_time; ++ unsigned int bfq_wr_min_idle_time; ++ unsigned long bfq_wr_min_inter_arr_async; ++ unsigned int bfq_wr_max_softrt_rate; ++ u64 RT_prod; ++ enum bfq_device_speed device_speed; ++ ++ struct bfq_queue oom_bfqq; ++}; ++ ++enum bfqq_state_flags { ++ BFQ_BFQQ_FLAG_busy = 0, /* has requests or is in service */ ++ BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */ ++ BFQ_BFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ ++ BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ ++ BFQ_BFQQ_FLAG_idle_window, /* slice idling enabled */ ++ BFQ_BFQQ_FLAG_sync, /* synchronous queue */ ++ BFQ_BFQQ_FLAG_budget_new, /* no completion with this budget */ ++ BFQ_BFQQ_FLAG_IO_bound, /* ++ * bfqq has timed-out at least once ++ * having consumed at most 2/10 of ++ * its budget ++ */ ++ BFQ_BFQQ_FLAG_in_large_burst, /* ++ * bfqq activated in a large burst, ++ * see comments to bfq_handle_burst. ++ */ ++ BFQ_BFQQ_FLAG_constantly_seeky, /* ++ * bfqq has proved to be slow and ++ * seeky until budget timeout ++ */ ++ BFQ_BFQQ_FLAG_softrt_update, /* ++ * may need softrt-next-start ++ * update ++ */ ++}; ++ ++#define BFQ_BFQQ_FNS(name) \ ++static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \ ++{ \ ++ (bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name); \ ++} \ ++static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \ ++{ \ ++ (bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name); \ ++} \ ++static int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ ++{ \ ++ return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \ ++} ++ ++BFQ_BFQQ_FNS(busy); ++BFQ_BFQQ_FNS(wait_request); ++BFQ_BFQQ_FNS(must_alloc); ++BFQ_BFQQ_FNS(fifo_expire); ++BFQ_BFQQ_FNS(idle_window); ++BFQ_BFQQ_FNS(sync); ++BFQ_BFQQ_FNS(budget_new); ++BFQ_BFQQ_FNS(IO_bound); ++BFQ_BFQQ_FNS(in_large_burst); ++BFQ_BFQQ_FNS(constantly_seeky); ++BFQ_BFQQ_FNS(softrt_update); ++#undef BFQ_BFQQ_FNS ++ ++/* Logging facilities. */ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq%d " fmt, (bfqq)->pid, ##args) ++ ++#define bfq_log(bfqd, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) ++ ++/* Expiration reasons. */ ++enum bfqq_expiration { ++ BFQ_BFQQ_TOO_IDLE = 0, /* ++ * queue has been idling for ++ * too long ++ */ ++ BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */ ++ BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */ ++ BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */ ++}; ++ ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ ++struct bfqg_stats { ++ /* total bytes transferred */ ++ struct blkg_rwstat service_bytes; ++ /* total IOs serviced, post merge */ ++ struct blkg_rwstat serviced; ++ /* number of ios merged */ ++ struct blkg_rwstat merged; ++ /* total time spent on device in ns, may not be accurate w/ queueing */ ++ struct blkg_rwstat service_time; ++ /* total time spent waiting in scheduler queue in ns */ ++ struct blkg_rwstat wait_time; ++ /* number of IOs queued up */ ++ struct blkg_rwstat queued; ++ /* total sectors transferred */ ++ struct blkg_stat sectors; ++ /* total disk time and nr sectors dispatched by this group */ ++ struct blkg_stat time; ++ /* time not charged to this cgroup */ ++ struct blkg_stat unaccounted_time; ++ /* sum of number of ios queued across all samples */ ++ struct blkg_stat avg_queue_size_sum; ++ /* count of samples taken for average */ ++ struct blkg_stat avg_queue_size_samples; ++ /* how many times this group has been removed from service tree */ ++ struct blkg_stat dequeue; ++ /* total time spent waiting for it to be assigned a timeslice. */ ++ struct blkg_stat group_wait_time; ++ /* time spent idling for this blkcg_gq */ ++ struct blkg_stat idle_time; ++ /* total time with empty current active q with other requests queued */ ++ struct blkg_stat empty_time; ++ /* fields after this shouldn't be cleared on stat reset */ ++ uint64_t start_group_wait_time; ++ uint64_t start_idle_time; ++ uint64_t start_empty_time; ++ uint16_t flags; ++}; ++ ++/* ++ * struct bfq_group_data - per-blkcg storage for the blkio subsystem. ++ * ++ * @ps: @blkcg_policy_storage that this structure inherits ++ * @weight: weight of the bfq_group ++ */ ++struct bfq_group_data { ++ /* must be the first member */ ++ struct blkcg_policy_data pd; ++ ++ unsigned short weight; ++}; ++ ++/** ++ * struct bfq_group - per (device, cgroup) data structure. ++ * @entity: schedulable entity to insert into the parent group sched_data. ++ * @sched_data: own sched_data, to contain child entities (they may be ++ * both bfq_queues and bfq_groups). ++ * @bfqd: the bfq_data for the device this group acts upon. ++ * @async_bfqq: array of async queues for all the tasks belonging to ++ * the group, one queue per ioprio value per ioprio_class, ++ * except for the idle class that has only one queue. ++ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored). ++ * @my_entity: pointer to @entity, %NULL for the toplevel group; used ++ * to avoid too many special cases during group creation/ ++ * migration. ++ * @active_entities: number of active entities belonging to the group; ++ * unused for the root group. Used to know whether there ++ * are groups with more than one active @bfq_entity ++ * (see the comments to the function ++ * bfq_bfqq_must_not_expire()). ++ * ++ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup ++ * there is a set of bfq_groups, each one collecting the lower-level ++ * entities belonging to the group that are acting on the same device. ++ * ++ * Locking works as follows: ++ * o @bfqd is protected by the queue lock, RCU is used to access it ++ * from the readers. ++ * o All the other fields are protected by the @bfqd queue lock. ++ */ ++struct bfq_group { ++ /* must be the first member */ ++ struct blkg_policy_data pd; ++ ++ struct bfq_entity entity; ++ struct bfq_sched_data sched_data; ++ ++ void *bfqd; ++ ++ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; ++ struct bfq_queue *async_idle_bfqq; ++ ++ struct bfq_entity *my_entity; ++ ++ int active_entities; ++ ++ struct bfqg_stats stats; ++ struct bfqg_stats dead_stats; /* stats pushed from dead children */ ++}; ++ ++#else ++struct bfq_group { ++ struct bfq_sched_data sched_data; ++ ++ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; ++ struct bfq_queue *async_idle_bfqq; ++}; ++#endif ++ ++static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); ++ ++static struct bfq_service_tree * ++bfq_entity_service_tree(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sched_data = entity->sched_data; ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ unsigned int idx = bfqq ? bfqq->ioprio_class - 1 : ++ BFQ_DEFAULT_GRP_CLASS; ++ ++ BUG_ON(idx >= BFQ_IOPRIO_CLASSES); ++ BUG_ON(sched_data == NULL); ++ ++ return sched_data->service_tree + idx; ++} ++ ++static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync) ++{ ++ return bic->bfqq[is_sync]; ++} ++ ++static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, ++ bool is_sync) ++{ ++ bic->bfqq[is_sync] = bfqq; ++} ++ ++static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic) ++{ ++ return bic->icq.q->elevator->elevator_data; ++} ++ ++/** ++ * bfq_get_bfqd_locked - get a lock to a bfqd using a RCU protected pointer. ++ * @ptr: a pointer to a bfqd. ++ * @flags: storage for the flags to be saved. ++ * ++ * This function allows bfqg->bfqd to be protected by the ++ * queue lock of the bfqd they reference; the pointer is dereferenced ++ * under RCU, so the storage for bfqd is assured to be safe as long ++ * as the RCU read side critical section does not end. After the ++ * bfqd->queue->queue_lock is taken the pointer is rechecked, to be ++ * sure that no other writer accessed it. If we raced with a writer, ++ * the function returns NULL, with the queue unlocked, otherwise it ++ * returns the dereferenced pointer, with the queue locked. ++ */ ++static struct bfq_data *bfq_get_bfqd_locked(void **ptr, unsigned long *flags) ++{ ++ struct bfq_data *bfqd; ++ ++ rcu_read_lock(); ++ bfqd = rcu_dereference(*(struct bfq_data **)ptr); ++ ++ if (bfqd != NULL) { ++ spin_lock_irqsave(bfqd->queue->queue_lock, *flags); ++ if (ptr == NULL) ++ printk(KERN_CRIT "get_bfqd_locked pointer NULL\n"); ++ else if (*ptr == bfqd) ++ goto out; ++ spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); ++ } ++ ++ bfqd = NULL; ++out: ++ rcu_read_unlock(); ++ return bfqd; ++} ++ ++static void bfq_put_bfqd_unlock(struct bfq_data *bfqd, unsigned long *flags) ++{ ++ spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); ++} ++ ++static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio); ++static void bfq_put_queue(struct bfq_queue *bfqq); ++static void bfq_dispatch_insert(struct request_queue *q, struct request *rq); ++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, ++ struct bio *bio, int is_sync, ++ struct bfq_io_cq *bic, gfp_t gfp_mask); ++static void bfq_end_wr_async_queues(struct bfq_data *bfqd, ++ struct bfq_group *bfqg); ++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); ++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); ++ ++#endif /* _BFQ_H */ +-- +1.9.1 + diff --git a/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.6.patch b/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.6.patch new file mode 100644 index 0000000..3a1c06d --- /dev/null +++ b/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.6.patch @@ -0,0 +1,1101 @@ +From c41c6d65f72971e565e7980db2c34224ca06fffd Mon Sep 17 00:00:00 2001 +From: Mauro Andreolini +Date: Sun, 6 Sep 2015 16:09:05 +0200 +Subject: [PATCH 3/4] block, bfq: add Early Queue Merge (EQM) to BFQ-v7r11 for + 4.6.0 + +A set of processes may happen to perform interleaved reads, i.e.,requests +whose union would give rise to a sequential read pattern. There are two +typical cases: in the first case, processes read fixed-size chunks of +data at a fixed distance from each other, while in the second case processes +may read variable-size chunks at variable distances. The latter case occurs +for example with QEMU, which splits the I/O generated by the guest into +multiple chunks, and lets these chunks be served by a pool of cooperating +processes, iteratively assigning the next chunk of I/O to the first +available process. CFQ uses actual queue merging for the first type of +rocesses, whereas it uses preemption to get a sequential read pattern out +of the read requests performed by the second type of processes. In the end +it uses two different mechanisms to achieve the same goal: boosting the +throughput with interleaved I/O. + +This patch introduces Early Queue Merge (EQM), a unified mechanism to get a +sequential read pattern with both types of processes. The main idea is +checking newly arrived requests against the next request of the active queue +both in case of actual request insert and in case of request merge. By doing +so, both the types of processes can be handled by just merging their queues. +EQM is then simpler and more compact than the pair of mechanisms used in +CFQ. + +Finally, EQM also preserves the typical low-latency properties of BFQ, by +properly restoring the weight-raising state of a queue when it gets back to +a non-merged state. + +Signed-off-by: Mauro Andreolini +Signed-off-by: Arianna Avanzini +Signed-off-by: Paolo Valente +Signed-off-by: Linus Walleij +--- + block/bfq-cgroup.c | 4 + + block/bfq-iosched.c | 687 ++++++++++++++++++++++++++++++++++++++++++++++++++-- + block/bfq.h | 66 +++++ + 3 files changed, 743 insertions(+), 14 deletions(-) + +diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c +index 8610cd6..5ee99ec 100644 +--- a/block/bfq-cgroup.c ++++ b/block/bfq-cgroup.c +@@ -437,6 +437,7 @@ static void bfq_pd_init(struct blkg_policy_data *pd) + */ + bfqg->bfqd = bfqd; + bfqg->active_entities = 0; ++ bfqg->rq_pos_tree = RB_ROOT; + } + + static void bfq_pd_free(struct blkg_policy_data *pd) +@@ -530,6 +531,8 @@ static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd, + return bfqg; + } + ++static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq); ++ + /** + * bfq_bfqq_move - migrate @bfqq to @bfqg. + * @bfqd: queue descriptor. +@@ -577,6 +580,7 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bfqg_get(bfqg); + + if (busy) { ++ bfq_pos_tree_add_move(bfqd, bfqq); + if (resume) + bfq_activate_bfqq(bfqd, bfqq); + } +diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c +index f9787a6..d1f648d 100644 +--- a/block/bfq-iosched.c ++++ b/block/bfq-iosched.c +@@ -296,6 +296,72 @@ static struct request *bfq_choose_req(struct bfq_data *bfqd, + } + } + ++static struct bfq_queue * ++bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root, ++ sector_t sector, struct rb_node **ret_parent, ++ struct rb_node ***rb_link) ++{ ++ struct rb_node **p, *parent; ++ struct bfq_queue *bfqq = NULL; ++ ++ parent = NULL; ++ p = &root->rb_node; ++ while (*p) { ++ struct rb_node **n; ++ ++ parent = *p; ++ bfqq = rb_entry(parent, struct bfq_queue, pos_node); ++ ++ /* ++ * Sort strictly based on sector. Smallest to the left, ++ * largest to the right. ++ */ ++ if (sector > blk_rq_pos(bfqq->next_rq)) ++ n = &(*p)->rb_right; ++ else if (sector < blk_rq_pos(bfqq->next_rq)) ++ n = &(*p)->rb_left; ++ else ++ break; ++ p = n; ++ bfqq = NULL; ++ } ++ ++ *ret_parent = parent; ++ if (rb_link) ++ *rb_link = p; ++ ++ bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d", ++ (long long unsigned)sector, ++ bfqq ? bfqq->pid : 0); ++ ++ return bfqq; ++} ++ ++static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct rb_node **p, *parent; ++ struct bfq_queue *__bfqq; ++ ++ if (bfqq->pos_root) { ++ rb_erase(&bfqq->pos_node, bfqq->pos_root); ++ bfqq->pos_root = NULL; ++ } ++ ++ if (bfq_class_idle(bfqq)) ++ return; ++ if (!bfqq->next_rq) ++ return; ++ ++ bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree; ++ __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root, ++ blk_rq_pos(bfqq->next_rq), &parent, &p); ++ if (!__bfqq) { ++ rb_link_node(&bfqq->pos_node, parent, p); ++ rb_insert_color(&bfqq->pos_node, bfqq->pos_root); ++ } else ++ bfqq->pos_root = NULL; ++} ++ + /* + * Tell whether there are active queues or groups with differentiated weights. + */ +@@ -528,6 +594,57 @@ static unsigned int bfq_wr_duration(struct bfq_data *bfqd) + return dur; + } + ++static unsigned bfq_bfqq_cooperations(struct bfq_queue *bfqq) ++{ ++ return bfqq->bic ? bfqq->bic->cooperations : 0; ++} ++ ++static void ++bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic) ++{ ++ if (bic->saved_idle_window) ++ bfq_mark_bfqq_idle_window(bfqq); ++ else ++ bfq_clear_bfqq_idle_window(bfqq); ++ if (bic->saved_IO_bound) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ else ++ bfq_clear_bfqq_IO_bound(bfqq); ++ /* Assuming that the flag in_large_burst is already correctly set */ ++ if (bic->wr_time_left && bfqq->bfqd->low_latency && ++ !bfq_bfqq_in_large_burst(bfqq) && ++ bic->cooperations < bfqq->bfqd->bfq_coop_thresh) { ++ /* ++ * Start a weight raising period with the duration given by ++ * the raising_time_left snapshot. ++ */ ++ if (bfq_bfqq_busy(bfqq)) ++ bfqq->bfqd->wr_busy_queues++; ++ bfqq->wr_coeff = bfqq->bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bic->wr_time_left; ++ bfqq->last_wr_start_finish = jiffies; ++ bfqq->entity.prio_changed = 1; ++ } ++ /* ++ * Clear wr_time_left to prevent bfq_bfqq_save_state() from ++ * getting confused about the queue's need of a weight-raising ++ * period. ++ */ ++ bic->wr_time_left = 0; ++} ++ ++static int bfqq_process_refs(struct bfq_queue *bfqq) ++{ ++ int process_refs, io_refs; ++ ++ lockdep_assert_held(bfqq->bfqd->queue->queue_lock); ++ ++ io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE]; ++ process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st; ++ BUG_ON(process_refs < 0); ++ return process_refs; ++} ++ + /* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */ + static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq) + { +@@ -764,8 +881,14 @@ static void bfq_add_request(struct request *rq) + BUG_ON(!next_rq); + bfqq->next_rq = next_rq; + ++ /* ++ * Adjust priority tree position, if next_rq changes. ++ */ ++ if (prev != bfqq->next_rq) ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ + if (!bfq_bfqq_busy(bfqq)) { +- bool soft_rt, in_burst, ++ bool soft_rt, coop_or_in_burst, + idle_for_long_time = time_is_before_jiffies( + bfqq->budget_timeout + + bfqd->bfq_wr_min_idle_time); +@@ -793,11 +916,12 @@ static void bfq_add_request(struct request *rq) + bfqd->last_ins_in_burst = jiffies; + } + +- in_burst = bfq_bfqq_in_large_burst(bfqq); ++ coop_or_in_burst = bfq_bfqq_in_large_burst(bfqq) || ++ bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh; + soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && +- !in_burst && ++ !coop_or_in_burst && + time_is_before_jiffies(bfqq->soft_rt_next_start); +- interactive = !in_burst && idle_for_long_time; ++ interactive = !coop_or_in_burst && idle_for_long_time; + entity->budget = max_t(unsigned long, bfqq->max_budget, + bfq_serv_to_charge(next_rq, bfqq)); + +@@ -816,6 +940,9 @@ static void bfq_add_request(struct request *rq) + if (!bfqd->low_latency) + goto add_bfqq_busy; + ++ if (bfq_bfqq_just_split(bfqq)) ++ goto set_prio_changed; ++ + /* + * If the queue: + * - is not being boosted, +@@ -840,7 +967,7 @@ static void bfq_add_request(struct request *rq) + } else if (old_wr_coeff > 1) { + if (interactive) + bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); +- else if (in_burst || ++ else if (coop_or_in_burst || + (bfqq->wr_cur_max_time == + bfqd->bfq_wr_rt_max_time && + !soft_rt)) { +@@ -905,6 +1032,7 @@ static void bfq_add_request(struct request *rq) + bfqd->bfq_wr_rt_max_time; + } + } ++set_prio_changed: + if (old_wr_coeff != bfqq->wr_coeff) + entity->prio_changed = 1; + add_bfqq_busy: +@@ -1047,6 +1175,15 @@ static void bfq_merged_request(struct request_queue *q, struct request *req, + bfqd->last_position); + BUG_ON(!next_rq); + bfqq->next_rq = next_rq; ++ /* ++ * If next_rq changes, update both the queue's budget to ++ * fit the new request and the queue's position in its ++ * rq_pos_tree. ++ */ ++ if (prev != bfqq->next_rq) { ++ bfq_updated_next_req(bfqd, bfqq); ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ } + } + } + +@@ -1129,11 +1266,346 @@ static void bfq_end_wr(struct bfq_data *bfqd) + spin_unlock_irq(bfqd->queue->queue_lock); + } + ++static sector_t bfq_io_struct_pos(void *io_struct, bool request) ++{ ++ if (request) ++ return blk_rq_pos(io_struct); ++ else ++ return ((struct bio *)io_struct)->bi_iter.bi_sector; ++} ++ ++static int bfq_rq_close_to_sector(void *io_struct, bool request, ++ sector_t sector) ++{ ++ return abs(bfq_io_struct_pos(io_struct, request) - sector) <= ++ BFQQ_SEEK_THR; ++} ++ ++static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ sector_t sector) ++{ ++ struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree; ++ struct rb_node *parent, *node; ++ struct bfq_queue *__bfqq; ++ ++ if (RB_EMPTY_ROOT(root)) ++ return NULL; ++ ++ /* ++ * First, if we find a request starting at the end of the last ++ * request, choose it. ++ */ ++ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL); ++ if (__bfqq) ++ return __bfqq; ++ ++ /* ++ * If the exact sector wasn't found, the parent of the NULL leaf ++ * will contain the closest sector (rq_pos_tree sorted by ++ * next_request position). ++ */ ++ __bfqq = rb_entry(parent, struct bfq_queue, pos_node); ++ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector)) ++ return __bfqq; ++ ++ if (blk_rq_pos(__bfqq->next_rq) < sector) ++ node = rb_next(&__bfqq->pos_node); ++ else ++ node = rb_prev(&__bfqq->pos_node); ++ if (!node) ++ return NULL; ++ ++ __bfqq = rb_entry(node, struct bfq_queue, pos_node); ++ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector)) ++ return __bfqq; ++ ++ return NULL; ++} ++ ++static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd, ++ struct bfq_queue *cur_bfqq, ++ sector_t sector) ++{ ++ struct bfq_queue *bfqq; ++ ++ /* ++ * We shall notice if some of the queues are cooperating, ++ * e.g., working closely on the same area of the device. In ++ * that case, we can group them together and: 1) don't waste ++ * time idling, and 2) serve the union of their requests in ++ * the best possible order for throughput. ++ */ ++ bfqq = bfqq_find_close(bfqd, cur_bfqq, sector); ++ if (!bfqq || bfqq == cur_bfqq) ++ return NULL; ++ ++ return bfqq; ++} ++ ++static struct bfq_queue * ++bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ int process_refs, new_process_refs; ++ struct bfq_queue *__bfqq; ++ ++ /* ++ * If there are no process references on the new_bfqq, then it is ++ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain ++ * may have dropped their last reference (not just their last process ++ * reference). ++ */ ++ if (!bfqq_process_refs(new_bfqq)) ++ return NULL; ++ ++ /* Avoid a circular list and skip interim queue merges. */ ++ while ((__bfqq = new_bfqq->new_bfqq)) { ++ if (__bfqq == bfqq) ++ return NULL; ++ new_bfqq = __bfqq; ++ } ++ ++ process_refs = bfqq_process_refs(bfqq); ++ new_process_refs = bfqq_process_refs(new_bfqq); ++ /* ++ * If the process for the bfqq has gone away, there is no ++ * sense in merging the queues. ++ */ ++ if (process_refs == 0 || new_process_refs == 0) ++ return NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", ++ new_bfqq->pid); ++ ++ /* ++ * Merging is just a redirection: the requests of the process ++ * owning one of the two queues are redirected to the other queue. ++ * The latter queue, in its turn, is set as shared if this is the ++ * first time that the requests of some process are redirected to ++ * it. ++ * ++ * We redirect bfqq to new_bfqq and not the opposite, because we ++ * are in the context of the process owning bfqq, hence we have ++ * the io_cq of this process. So we can immediately configure this ++ * io_cq to redirect the requests of the process to new_bfqq. ++ * ++ * NOTE, even if new_bfqq coincides with the in-service queue, the ++ * io_cq of new_bfqq is not available, because, if the in-service ++ * queue is shared, bfqd->in_service_bic may not point to the ++ * io_cq of the in-service queue. ++ * Redirecting the requests of the process owning bfqq to the ++ * currently in-service queue is in any case the best option, as ++ * we feed the in-service queue with new requests close to the ++ * last request served and, by doing so, hopefully increase the ++ * throughput. ++ */ ++ bfqq->new_bfqq = new_bfqq; ++ atomic_add(process_refs, &new_bfqq->ref); ++ return new_bfqq; ++} ++ ++static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq, ++ struct bfq_queue *new_bfqq) ++{ ++ if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) || ++ (bfqq->ioprio_class != new_bfqq->ioprio_class)) ++ return false; ++ ++ /* ++ * If either of the queues has already been detected as seeky, ++ * then merging it with the other queue is unlikely to lead to ++ * sequential I/O. ++ */ ++ if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq)) ++ return false; ++ ++ /* ++ * Interleaved I/O is known to be done by (some) applications ++ * only for reads, so it does not make sense to merge async ++ * queues. ++ */ ++ if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq)) ++ return false; ++ ++ return true; ++} ++ ++/* ++ * Attempt to schedule a merge of bfqq with the currently in-service queue ++ * or with a close queue among the scheduled queues. ++ * Return NULL if no merge was scheduled, a pointer to the shared bfq_queue ++ * structure otherwise. ++ * ++ * The OOM queue is not allowed to participate to cooperation: in fact, since ++ * the requests temporarily redirected to the OOM queue could be redirected ++ * again to dedicated queues at any time, the state needed to correctly ++ * handle merging with the OOM queue would be quite complex and expensive ++ * to maintain. Besides, in such a critical condition as an out of memory, ++ * the benefits of queue merging may be little relevant, or even negligible. ++ */ ++static struct bfq_queue * ++bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ void *io_struct, bool request) ++{ ++ struct bfq_queue *in_service_bfqq, *new_bfqq; ++ ++ if (bfqq->new_bfqq) ++ return bfqq->new_bfqq; ++ if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) ++ return NULL; ++ /* If device has only one backlogged bfq_queue, don't search. */ ++ if (bfqd->busy_queues == 1) ++ return NULL; ++ ++ in_service_bfqq = bfqd->in_service_queue; ++ ++ if (!in_service_bfqq || in_service_bfqq == bfqq || ++ !bfqd->in_service_bic || ++ unlikely(in_service_bfqq == &bfqd->oom_bfqq)) ++ goto check_scheduled; ++ ++ if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) && ++ bfqq->entity.parent == in_service_bfqq->entity.parent && ++ bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) { ++ new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq); ++ if (new_bfqq) ++ return new_bfqq; ++ } ++ /* ++ * Check whether there is a cooperator among currently scheduled ++ * queues. The only thing we need is that the bio/request is not ++ * NULL, as we need it to establish whether a cooperator exists. ++ */ ++check_scheduled: ++ new_bfqq = bfq_find_close_cooperator(bfqd, bfqq, ++ bfq_io_struct_pos(io_struct, request)); ++ ++ BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent); ++ ++ if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) && ++ bfq_may_be_close_cooperator(bfqq, new_bfqq)) ++ return bfq_setup_merge(bfqq, new_bfqq); ++ ++ return NULL; ++} ++ ++static void bfq_bfqq_save_state(struct bfq_queue *bfqq) ++{ ++ /* ++ * If !bfqq->bic, the queue is already shared or its requests ++ * have already been redirected to a shared queue; both idle window ++ * and weight raising state have already been saved. Do nothing. ++ */ ++ if (!bfqq->bic) ++ return; ++ if (bfqq->bic->wr_time_left) ++ /* ++ * This is the queue of a just-started process, and would ++ * deserve weight raising: we set wr_time_left to the full ++ * weight-raising duration to trigger weight-raising when ++ * and if the queue is split and the first request of the ++ * queue is enqueued. ++ */ ++ bfqq->bic->wr_time_left = bfq_wr_duration(bfqq->bfqd); ++ else if (bfqq->wr_coeff > 1) { ++ unsigned long wr_duration = ++ jiffies - bfqq->last_wr_start_finish; ++ /* ++ * It may happen that a queue's weight raising period lasts ++ * longer than its wr_cur_max_time, as weight raising is ++ * handled only when a request is enqueued or dispatched (it ++ * does not use any timer). If the weight raising period is ++ * about to end, don't save it. ++ */ ++ if (bfqq->wr_cur_max_time <= wr_duration) ++ bfqq->bic->wr_time_left = 0; ++ else ++ bfqq->bic->wr_time_left = ++ bfqq->wr_cur_max_time - wr_duration; ++ /* ++ * The bfq_queue is becoming shared or the requests of the ++ * process owning the queue are being redirected to a shared ++ * queue. Stop the weight raising period of the queue, as in ++ * both cases it should not be owned by an interactive or ++ * soft real-time application. ++ */ ++ bfq_bfqq_end_wr(bfqq); ++ } else ++ bfqq->bic->wr_time_left = 0; ++ bfqq->bic->saved_idle_window = bfq_bfqq_idle_window(bfqq); ++ bfqq->bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq); ++ bfqq->bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq); ++ bfqq->bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node); ++ bfqq->bic->cooperations++; ++ bfqq->bic->failed_cooperations = 0; ++} ++ ++static void bfq_get_bic_reference(struct bfq_queue *bfqq) ++{ ++ /* ++ * If bfqq->bic has a non-NULL value, the bic to which it belongs ++ * is about to begin using a shared bfq_queue. ++ */ ++ if (bfqq->bic) ++ atomic_long_inc(&bfqq->bic->icq.ioc->refcount); ++} ++ ++static void ++bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, ++ struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu", ++ (long unsigned)new_bfqq->pid); ++ /* Save weight raising and idle window of the merged queues */ ++ bfq_bfqq_save_state(bfqq); ++ bfq_bfqq_save_state(new_bfqq); ++ if (bfq_bfqq_IO_bound(bfqq)) ++ bfq_mark_bfqq_IO_bound(new_bfqq); ++ bfq_clear_bfqq_IO_bound(bfqq); ++ /* ++ * Grab a reference to the bic, to prevent it from being destroyed ++ * before being possibly touched by a bfq_split_bfqq(). ++ */ ++ bfq_get_bic_reference(bfqq); ++ bfq_get_bic_reference(new_bfqq); ++ /* ++ * Merge queues (that is, let bic redirect its requests to new_bfqq) ++ */ ++ bic_set_bfqq(bic, new_bfqq, 1); ++ bfq_mark_bfqq_coop(new_bfqq); ++ /* ++ * new_bfqq now belongs to at least two bics (it is a shared queue): ++ * set new_bfqq->bic to NULL. bfqq either: ++ * - does not belong to any bic any more, and hence bfqq->bic must ++ * be set to NULL, or ++ * - is a queue whose owning bics have already been redirected to a ++ * different queue, hence the queue is destined to not belong to ++ * any bic soon and bfqq->bic is already NULL (therefore the next ++ * assignment causes no harm). ++ */ ++ new_bfqq->bic = NULL; ++ bfqq->bic = NULL; ++ bfq_put_queue(bfqq); ++} ++ ++static void bfq_bfqq_increase_failed_cooperations(struct bfq_queue *bfqq) ++{ ++ struct bfq_io_cq *bic = bfqq->bic; ++ struct bfq_data *bfqd = bfqq->bfqd; ++ ++ if (bic && bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh) { ++ bic->failed_cooperations++; ++ if (bic->failed_cooperations >= bfqd->bfq_failed_cooperations) ++ bic->cooperations = 0; ++ } ++} ++ + static int bfq_allow_merge(struct request_queue *q, struct request *rq, + struct bio *bio) + { + struct bfq_data *bfqd = q->elevator->elevator_data; + struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq, *new_bfqq; + + /* + * Disallow merge of a sync bio into an async request. +@@ -1150,7 +1622,26 @@ static int bfq_allow_merge(struct request_queue *q, struct request *rq, + if (!bic) + return 0; + +- return bic_to_bfqq(bic, bfq_bio_sync(bio)) == RQ_BFQQ(rq); ++ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio)); ++ /* ++ * We take advantage of this function to perform an early merge ++ * of the queues of possible cooperating processes. ++ */ ++ if (bfqq) { ++ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false); ++ if (new_bfqq) { ++ bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq); ++ /* ++ * If we get here, the bio will be queued in the ++ * shared queue, i.e., new_bfqq, so use new_bfqq ++ * to decide whether bio and rq can be merged. ++ */ ++ bfqq = new_bfqq; ++ } else ++ bfq_bfqq_increase_failed_cooperations(bfqq); ++ } ++ ++ return bfqq == RQ_BFQQ(rq); + } + + static void __bfq_set_in_service_queue(struct bfq_data *bfqd, +@@ -1349,6 +1840,15 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) + + __bfq_bfqd_reset_in_service(bfqd); + ++ /* ++ * If this bfqq is shared between multiple processes, check ++ * to make sure that those processes are still issuing I/Os ++ * within the mean seek distance. If not, it may be time to ++ * break the queues apart again. ++ */ ++ if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq)) ++ bfq_mark_bfqq_split_coop(bfqq); ++ + if (RB_EMPTY_ROOT(&bfqq->sort_list)) { + /* + * Overloading budget_timeout field to store the time +@@ -1357,8 +1857,13 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) + */ + bfqq->budget_timeout = jiffies; + bfq_del_bfqq_busy(bfqd, bfqq, 1); +- } else ++ } else { + bfq_activate_bfqq(bfqd, bfqq); ++ /* ++ * Resort priority tree of potential close cooperators. ++ */ ++ bfq_pos_tree_add_move(bfqd, bfqq); ++ } + } + + /** +@@ -2242,10 +2747,12 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq) + /* + * If the queue was activated in a burst, or + * too much time has elapsed from the beginning +- * of this weight-raising period, then end weight +- * raising. ++ * of this weight-raising period, or the queue has ++ * exceeded the acceptable number of cooperations, ++ * then end weight raising. + */ + if (bfq_bfqq_in_large_burst(bfqq) || ++ bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh || + time_is_before_jiffies(bfqq->last_wr_start_finish + + bfqq->wr_cur_max_time)) { + bfqq->last_wr_start_finish = jiffies; +@@ -2474,6 +2981,25 @@ static void bfq_put_queue(struct bfq_queue *bfqq) + #endif + } + ++static void bfq_put_cooperator(struct bfq_queue *bfqq) ++{ ++ struct bfq_queue *__bfqq, *next; ++ ++ /* ++ * If this queue was scheduled to merge with another queue, be ++ * sure to drop the reference taken on that queue (and others in ++ * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs. ++ */ ++ __bfqq = bfqq->new_bfqq; ++ while (__bfqq) { ++ if (__bfqq == bfqq) ++ break; ++ next = __bfqq->new_bfqq; ++ bfq_put_queue(__bfqq); ++ __bfqq = next; ++ } ++} ++ + static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) + { + if (bfqq == bfqd->in_service_queue) { +@@ -2484,6 +3010,8 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) + bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, + atomic_read(&bfqq->ref)); + ++ bfq_put_cooperator(bfqq); ++ + bfq_put_queue(bfqq); + } + +@@ -2492,6 +3020,25 @@ static void bfq_init_icq(struct io_cq *icq) + struct bfq_io_cq *bic = icq_to_bic(icq); + + bic->ttime.last_end_request = jiffies; ++ /* ++ * A newly created bic indicates that the process has just ++ * started doing I/O, and is probably mapping into memory its ++ * executable and libraries: it definitely needs weight raising. ++ * There is however the possibility that the process performs, ++ * for a while, I/O close to some other process. EQM intercepts ++ * this behavior and may merge the queue corresponding to the ++ * process with some other queue, BEFORE the weight of the queue ++ * is raised. Merged queues are not weight-raised (they are assumed ++ * to belong to processes that benefit only from high throughput). ++ * If the merge is basically the consequence of an accident, then ++ * the queue will be split soon and will get back its old weight. ++ * It is then important to write down somewhere that this queue ++ * does need weight raising, even if it did not make it to get its ++ * weight raised before being merged. To this purpose, we overload ++ * the field raising_time_left and assign 1 to it, to mark the queue ++ * as needing weight raising. ++ */ ++ bic->wr_time_left = 1; + } + + static void bfq_exit_icq(struct io_cq *icq) +@@ -2505,6 +3052,13 @@ static void bfq_exit_icq(struct io_cq *icq) + } + + if (bic->bfqq[BLK_RW_SYNC]) { ++ /* ++ * If the bic is using a shared queue, put the reference ++ * taken on the io_context when the bic started using a ++ * shared bfq_queue. ++ */ ++ if (bfq_bfqq_coop(bic->bfqq[BLK_RW_SYNC])) ++ put_io_context(icq->ioc); + bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]); + bic->bfqq[BLK_RW_SYNC] = NULL; + } +@@ -2809,6 +3363,10 @@ static void bfq_update_idle_window(struct bfq_data *bfqd, + if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq)) + return; + ++ /* Idle window just restored, statistics are meaningless. */ ++ if (bfq_bfqq_just_split(bfqq)) ++ return; ++ + enable_idle = bfq_bfqq_idle_window(bfqq); + + if (atomic_read(&bic->icq.ioc->active_ref) == 0 || +@@ -2856,6 +3414,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, + if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 || + !BFQQ_SEEKY(bfqq)) + bfq_update_idle_window(bfqd, bfqq, bic); ++ bfq_clear_bfqq_just_split(bfqq); + + bfq_log_bfqq(bfqd, bfqq, + "rq_enqueued: idle_window=%d (seeky %d, mean %llu)", +@@ -2920,12 +3479,47 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, + static void bfq_insert_request(struct request_queue *q, struct request *rq) + { + struct bfq_data *bfqd = q->elevator->elevator_data; +- struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq; + + assert_spin_locked(bfqd->queue->queue_lock); + ++ /* ++ * An unplug may trigger a requeue of a request from the device ++ * driver: make sure we are in process context while trying to ++ * merge two bfq_queues. ++ */ ++ if (!in_interrupt()) { ++ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true); ++ if (new_bfqq) { ++ if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq) ++ new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1); ++ /* ++ * Release the request's reference to the old bfqq ++ * and make sure one is taken to the shared queue. ++ */ ++ new_bfqq->allocated[rq_data_dir(rq)]++; ++ bfqq->allocated[rq_data_dir(rq)]--; ++ atomic_inc(&new_bfqq->ref); ++ bfq_put_queue(bfqq); ++ if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq) ++ bfq_merge_bfqqs(bfqd, RQ_BIC(rq), ++ bfqq, new_bfqq); ++ rq->elv.priv[1] = new_bfqq; ++ bfqq = new_bfqq; ++ } else ++ bfq_bfqq_increase_failed_cooperations(bfqq); ++ } ++ + bfq_add_request(rq); + ++ /* ++ * Here a newly-created bfq_queue has already started a weight-raising ++ * period: clear raising_time_left to prevent bfq_bfqq_save_state() ++ * from assigning it a full weight-raising period. See the detailed ++ * comments about this field in bfq_init_icq(). ++ */ ++ if (bfqq->bic) ++ bfqq->bic->wr_time_left = 0; + rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; + list_add_tail(&rq->queuelist, &bfqq->fifo); + +@@ -3094,6 +3688,32 @@ static void bfq_put_request(struct request *rq) + } + + /* ++ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this ++ * was the last process referring to said bfqq. ++ */ ++static struct bfq_queue * ++bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue"); ++ ++ put_io_context(bic->icq.ioc); ++ ++ if (bfqq_process_refs(bfqq) == 1) { ++ bfqq->pid = current->pid; ++ bfq_clear_bfqq_coop(bfqq); ++ bfq_clear_bfqq_split_coop(bfqq); ++ return bfqq; ++ } ++ ++ bic_set_bfqq(bic, NULL, 1); ++ ++ bfq_put_cooperator(bfqq); ++ ++ bfq_put_queue(bfqq); ++ return NULL; ++} ++ ++/* + * Allocate bfq data structures associated with this request. + */ + static int bfq_set_request(struct request_queue *q, struct request *rq, +@@ -3105,6 +3725,7 @@ static int bfq_set_request(struct request_queue *q, struct request *rq, + const int is_sync = rq_is_sync(rq); + struct bfq_queue *bfqq; + unsigned long flags; ++ bool split = false; + + might_sleep_if(gfpflags_allow_blocking(gfp_mask)); + +@@ -3117,15 +3738,30 @@ static int bfq_set_request(struct request_queue *q, struct request *rq, + + bfq_bic_update_cgroup(bic, bio); + ++new_queue: + bfqq = bic_to_bfqq(bic, is_sync); + if (!bfqq || bfqq == &bfqd->oom_bfqq) { + bfqq = bfq_get_queue(bfqd, bio, is_sync, bic, gfp_mask); + bic_set_bfqq(bic, bfqq, is_sync); +- if (is_sync) { +- if (bfqd->large_burst) ++ if (split && is_sync) { ++ if ((bic->was_in_burst_list && bfqd->large_burst) || ++ bic->saved_in_large_burst) + bfq_mark_bfqq_in_large_burst(bfqq); +- else +- bfq_clear_bfqq_in_large_burst(bfqq); ++ else { ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ if (bic->was_in_burst_list) ++ hlist_add_head(&bfqq->burst_list_node, ++ &bfqd->burst_list); ++ } ++ } ++ } else { ++ /* If the queue was seeky for too long, break it apart. */ ++ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) { ++ bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq"); ++ bfqq = bfq_split_bfqq(bic, bfqq); ++ split = true; ++ if (!bfqq) ++ goto new_queue; + } + } + +@@ -3137,6 +3773,26 @@ static int bfq_set_request(struct request_queue *q, struct request *rq, + rq->elv.priv[0] = bic; + rq->elv.priv[1] = bfqq; + ++ /* ++ * If a bfq_queue has only one process reference, it is owned ++ * by only one bfq_io_cq: we can set the bic field of the ++ * bfq_queue to the address of that structure. Also, if the ++ * queue has just been split, mark a flag so that the ++ * information is available to the other scheduler hooks. ++ */ ++ if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) { ++ bfqq->bic = bic; ++ if (split) { ++ bfq_mark_bfqq_just_split(bfqq); ++ /* ++ * If the queue has just been split from a shared ++ * queue, restore the idle window and the possible ++ * weight raising period. ++ */ ++ bfq_bfqq_resume_state(bfqq, bic); ++ } ++ } ++ + spin_unlock_irqrestore(q->queue_lock, flags); + + return 0; +@@ -3290,6 +3946,7 @@ static void bfq_init_root_group(struct bfq_group *root_group, + root_group->my_entity = NULL; + root_group->bfqd = bfqd; + #endif ++ root_group->rq_pos_tree = RB_ROOT; + for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) + root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; + } +@@ -3370,6 +4027,8 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) + bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async; + bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync; + ++ bfqd->bfq_coop_thresh = 2; ++ bfqd->bfq_failed_cooperations = 7000; + bfqd->bfq_requests_within_timer = 120; + + bfqd->bfq_large_burst_thresh = 11; +diff --git a/block/bfq.h b/block/bfq.h +index 485d0c9..f73c942 100644 +--- a/block/bfq.h ++++ b/block/bfq.h +@@ -183,6 +183,8 @@ struct bfq_group; + * ioprio_class value. + * @new_bfqq: shared bfq_queue if queue is cooperating with + * one or more other queues. ++ * @pos_node: request-position tree member (see bfq_group's @rq_pos_tree). ++ * @pos_root: request-position tree root (see bfq_group's @rq_pos_tree). + * @sort_list: sorted list of pending requests. + * @next_rq: if fifo isn't expired, next request to serve. + * @queued: nr of requests queued in @sort_list. +@@ -304,6 +306,26 @@ struct bfq_ttime { + * @ttime: associated @bfq_ttime struct + * @ioprio: per (request_queue, blkcg) ioprio. + * @blkcg_id: id of the blkcg the related io_cq belongs to. ++ * @wr_time_left: snapshot of the time left before weight raising ends ++ * for the sync queue associated to this process; this ++ * snapshot is taken to remember this value while the weight ++ * raising is suspended because the queue is merged with a ++ * shared queue, and is used to set @raising_cur_max_time ++ * when the queue is split from the shared queue and its ++ * weight is raised again ++ * @saved_idle_window: same purpose as the previous field for the idle ++ * window ++ * @saved_IO_bound: same purpose as the previous two fields for the I/O ++ * bound classification of a queue ++ * @saved_in_large_burst: same purpose as the previous fields for the ++ * value of the field keeping the queue's belonging ++ * to a large burst ++ * @was_in_burst_list: true if the queue belonged to a burst list ++ * before its merge with another cooperating queue ++ * @cooperations: counter of consecutive successful queue merges underwent ++ * by any of the process' @bfq_queues ++ * @failed_cooperations: counter of consecutive failed queue merges of any ++ * of the process' @bfq_queues + */ + struct bfq_io_cq { + struct io_cq icq; /* must be the first member */ +@@ -314,6 +336,16 @@ struct bfq_io_cq { + #ifdef CONFIG_BFQ_GROUP_IOSCHED + uint64_t blkcg_id; /* the current blkcg ID */ + #endif ++ ++ unsigned int wr_time_left; ++ bool saved_idle_window; ++ bool saved_IO_bound; ++ ++ bool saved_in_large_burst; ++ bool was_in_burst_list; ++ ++ unsigned int cooperations; ++ unsigned int failed_cooperations; + }; + + enum bfq_device_speed { +@@ -557,6 +589,9 @@ enum bfqq_state_flags { + * may need softrt-next-start + * update + */ ++ BFQ_BFQQ_FLAG_coop, /* bfqq is shared */ ++ BFQ_BFQQ_FLAG_split_coop, /* shared bfqq will be split */ ++ BFQ_BFQQ_FLAG_just_split, /* queue has just been split */ + }; + + #define BFQ_BFQQ_FNS(name) \ +@@ -583,6 +618,9 @@ BFQ_BFQQ_FNS(budget_new); + BFQ_BFQQ_FNS(IO_bound); + BFQ_BFQQ_FNS(in_large_burst); + BFQ_BFQQ_FNS(constantly_seeky); ++BFQ_BFQQ_FNS(coop); ++BFQ_BFQQ_FNS(split_coop); ++BFQ_BFQQ_FNS(just_split); + BFQ_BFQQ_FNS(softrt_update); + #undef BFQ_BFQQ_FNS + +@@ -675,6 +713,9 @@ struct bfq_group_data { + * are groups with more than one active @bfq_entity + * (see the comments to the function + * bfq_bfqq_must_not_expire()). ++ * @rq_pos_tree: rbtree sorted by next_request position, used when ++ * determining if two or more queues have interleaving ++ * requests (see bfq_find_close_cooperator()). + * + * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup + * there is a set of bfq_groups, each one collecting the lower-level +@@ -701,6 +742,8 @@ struct bfq_group { + + int active_entities; + ++ struct rb_root rq_pos_tree; ++ + struct bfqg_stats stats; + struct bfqg_stats dead_stats; /* stats pushed from dead children */ + }; +@@ -711,6 +754,8 @@ struct bfq_group { + + struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; + struct bfq_queue *async_idle_bfqq; ++ ++ struct rb_root rq_pos_tree; + }; + #endif + +@@ -787,6 +832,27 @@ static void bfq_put_bfqd_unlock(struct bfq_data *bfqd, unsigned long *flags) + spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); + } + ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ ++static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *group_entity = bfqq->entity.parent; ++ ++ if (!group_entity) ++ group_entity = &bfqq->bfqd->root_group->entity; ++ ++ return container_of(group_entity, struct bfq_group, entity); ++} ++ ++#else ++ ++static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) ++{ ++ return bfqq->bfqd->root_group; ++} ++ ++#endif ++ + static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio); + static void bfq_put_queue(struct bfq_queue *bfqq); + static void bfq_dispatch_insert(struct request_queue *q, struct request *rq); +-- +1.9.1 + diff --git a/5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch2 b/5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch2 new file mode 100644 index 0000000..bbccb23 --- /dev/null +++ b/5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch2 @@ -0,0 +1,6361 @@ +From 62745bf5f16f14ce2bd56377eeb84615b4a19cd2 Mon Sep 17 00:00:00 2001 +From: Paolo Valente +Date: Tue, 17 May 2016 08:28:04 +0200 +Subject: [PATCH 4/4] blkck, bfq: turn BFQ-v7r11 for 4.7.0 into BFQ-v8 for + 4.7.0 + +--- + block/Kconfig.iosched | 2 +- + block/bfq-cgroup.c | 448 +++++---- + block/bfq-iosched.c | 2582 +++++++++++++++++++++++++++++-------------------- + block/bfq-sched.c | 432 +++++++-- + block/bfq.h | 697 +++++++------ + 5 files changed, 2433 insertions(+), 1728 deletions(-) + +diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched +index f78cd1a..6d92579 100644 +--- a/block/Kconfig.iosched ++++ b/block/Kconfig.iosched +@@ -53,7 +53,7 @@ config IOSCHED_BFQ + + config BFQ_GROUP_IOSCHED + bool "BFQ hierarchical scheduling support" +- depends on CGROUPS && IOSCHED_BFQ=y ++ depends on IOSCHED_BFQ && BLK_CGROUP + default n + ---help--- + Enable hierarchical scheduling in BFQ, using the blkio controller. +diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c +index 5ee99ec..bc01663 100644 +--- a/block/bfq-cgroup.c ++++ b/block/bfq-cgroup.c +@@ -162,7 +162,6 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg) + static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg) + { + struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq); +- BUG_ON(!pd); + return pd_to_bfqg(pd); + } + +@@ -224,14 +223,6 @@ static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, int rw) + blkg_rwstat_add(&bfqg->stats.merged, rw, 1); + } + +-static void bfqg_stats_update_dispatch(struct bfq_group *bfqg, +- uint64_t bytes, int rw) +-{ +- blkg_stat_add(&bfqg->stats.sectors, bytes >> 9); +- blkg_rwstat_add(&bfqg->stats.serviced, rw, 1); +- blkg_rwstat_add(&bfqg->stats.service_bytes, rw, bytes); +-} +- + static void bfqg_stats_update_completion(struct bfq_group *bfqg, + uint64_t start_time, uint64_t io_start_time, int rw) + { +@@ -248,17 +239,11 @@ static void bfqg_stats_update_completion(struct bfq_group *bfqg, + /* @stats = 0 */ + static void bfqg_stats_reset(struct bfqg_stats *stats) + { +- if (!stats) +- return; +- + /* queued stats shouldn't be cleared */ +- blkg_rwstat_reset(&stats->service_bytes); +- blkg_rwstat_reset(&stats->serviced); + blkg_rwstat_reset(&stats->merged); + blkg_rwstat_reset(&stats->service_time); + blkg_rwstat_reset(&stats->wait_time); + blkg_stat_reset(&stats->time); +- blkg_stat_reset(&stats->unaccounted_time); + blkg_stat_reset(&stats->avg_queue_size_sum); + blkg_stat_reset(&stats->avg_queue_size_samples); + blkg_stat_reset(&stats->dequeue); +@@ -268,21 +253,19 @@ static void bfqg_stats_reset(struct bfqg_stats *stats) + } + + /* @to += @from */ +-static void bfqg_stats_merge(struct bfqg_stats *to, struct bfqg_stats *from) ++static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from) + { + if (!to || !from) + return; + + /* queued stats shouldn't be cleared */ +- blkg_rwstat_add_aux(&to->service_bytes, &from->service_bytes); +- blkg_rwstat_add_aux(&to->serviced, &from->serviced); + blkg_rwstat_add_aux(&to->merged, &from->merged); + blkg_rwstat_add_aux(&to->service_time, &from->service_time); + blkg_rwstat_add_aux(&to->wait_time, &from->wait_time); + blkg_stat_add_aux(&from->time, &from->time); +- blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time); + blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum); +- blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples); ++ blkg_stat_add_aux(&to->avg_queue_size_samples, ++ &from->avg_queue_size_samples); + blkg_stat_add_aux(&to->dequeue, &from->dequeue); + blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time); + blkg_stat_add_aux(&to->idle_time, &from->idle_time); +@@ -308,10 +291,8 @@ static void bfqg_stats_xfer_dead(struct bfq_group *bfqg) + if (unlikely(!parent)) + return; + +- bfqg_stats_merge(&parent->dead_stats, &bfqg->stats); +- bfqg_stats_merge(&parent->dead_stats, &bfqg->dead_stats); ++ bfqg_stats_add_aux(&parent->stats, &bfqg->stats); + bfqg_stats_reset(&bfqg->stats); +- bfqg_stats_reset(&bfqg->dead_stats); + } + + static void bfq_init_entity(struct bfq_entity *entity, +@@ -332,15 +313,11 @@ static void bfq_init_entity(struct bfq_entity *entity, + + static void bfqg_stats_exit(struct bfqg_stats *stats) + { +- blkg_rwstat_exit(&stats->service_bytes); +- blkg_rwstat_exit(&stats->serviced); + blkg_rwstat_exit(&stats->merged); + blkg_rwstat_exit(&stats->service_time); + blkg_rwstat_exit(&stats->wait_time); + blkg_rwstat_exit(&stats->queued); +- blkg_stat_exit(&stats->sectors); + blkg_stat_exit(&stats->time); +- blkg_stat_exit(&stats->unaccounted_time); + blkg_stat_exit(&stats->avg_queue_size_sum); + blkg_stat_exit(&stats->avg_queue_size_samples); + blkg_stat_exit(&stats->dequeue); +@@ -351,15 +328,11 @@ static void bfqg_stats_exit(struct bfqg_stats *stats) + + static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) + { +- if (blkg_rwstat_init(&stats->service_bytes, gfp) || +- blkg_rwstat_init(&stats->serviced, gfp) || +- blkg_rwstat_init(&stats->merged, gfp) || ++ if (blkg_rwstat_init(&stats->merged, gfp) || + blkg_rwstat_init(&stats->service_time, gfp) || + blkg_rwstat_init(&stats->wait_time, gfp) || + blkg_rwstat_init(&stats->queued, gfp) || +- blkg_stat_init(&stats->sectors, gfp) || + blkg_stat_init(&stats->time, gfp) || +- blkg_stat_init(&stats->unaccounted_time, gfp) || + blkg_stat_init(&stats->avg_queue_size_sum, gfp) || + blkg_stat_init(&stats->avg_queue_size_samples, gfp) || + blkg_stat_init(&stats->dequeue, gfp) || +@@ -374,20 +347,36 @@ static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) + } + + static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd) +- { ++{ + return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL; +- } ++} + + static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg) + { + return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq)); + } + ++static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp) ++{ ++ struct bfq_group_data *bgd; ++ ++ bgd = kzalloc(sizeof(*bgd), GFP_KERNEL); ++ if (!bgd) ++ return NULL; ++ return &bgd->pd; ++} ++ + static void bfq_cpd_init(struct blkcg_policy_data *cpd) + { + struct bfq_group_data *d = cpd_to_bfqgd(cpd); + +- d->weight = BFQ_DEFAULT_GRP_WEIGHT; ++ d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ? ++ CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL; ++} ++ ++static void bfq_cpd_free(struct blkcg_policy_data *cpd) ++{ ++ kfree(cpd_to_bfqgd(cpd)); + } + + static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) +@@ -398,8 +387,7 @@ static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) + if (!bfqg) + return NULL; + +- if (bfqg_stats_init(&bfqg->stats, gfp) || +- bfqg_stats_init(&bfqg->dead_stats, gfp)) { ++ if (bfqg_stats_init(&bfqg->stats, gfp)) { + kfree(bfqg); + return NULL; + } +@@ -407,27 +395,20 @@ static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) + return &bfqg->pd; + } + +-static void bfq_group_set_parent(struct bfq_group *bfqg, +- struct bfq_group *parent) ++static void bfq_pd_init(struct blkg_policy_data *pd) + { ++ struct blkcg_gq *blkg; ++ struct bfq_group *bfqg; ++ struct bfq_data *bfqd; + struct bfq_entity *entity; ++ struct bfq_group_data *d; + +- BUG_ON(!parent); +- BUG_ON(!bfqg); +- BUG_ON(bfqg == parent); +- ++ blkg = pd_to_blkg(pd); ++ BUG_ON(!blkg); ++ bfqg = blkg_to_bfqg(blkg); ++ bfqd = blkg->q->elevator->elevator_data; + entity = &bfqg->entity; +- entity->parent = parent->my_entity; +- entity->sched_data = &parent->sched_data; +-} +- +-static void bfq_pd_init(struct blkg_policy_data *pd) +-{ +- struct blkcg_gq *blkg = pd_to_blkg(pd); +- struct bfq_group *bfqg = blkg_to_bfqg(blkg); +- struct bfq_data *bfqd = blkg->q->elevator->elevator_data; +- struct bfq_entity *entity = &bfqg->entity; +- struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg); ++ d = blkcg_to_bfqgd(blkg->blkcg); + + entity->orig_weight = entity->weight = entity->new_weight = d->weight; + entity->my_sched_data = &bfqg->sched_data; +@@ -445,45 +426,28 @@ static void bfq_pd_free(struct blkg_policy_data *pd) + struct bfq_group *bfqg = pd_to_bfqg(pd); + + bfqg_stats_exit(&bfqg->stats); +- bfqg_stats_exit(&bfqg->dead_stats); +- + return kfree(bfqg); + } + +-/* offset delta from bfqg->stats to bfqg->dead_stats */ +-static const int dead_stats_off_delta = offsetof(struct bfq_group, dead_stats) - +- offsetof(struct bfq_group, stats); +- +-/* to be used by recursive prfill, sums live and dead stats recursively */ +-static u64 bfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off) ++static void bfq_pd_reset_stats(struct blkg_policy_data *pd) + { +- u64 sum = 0; ++ struct bfq_group *bfqg = pd_to_bfqg(pd); + +- sum += blkg_stat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off); +- sum += blkg_stat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, +- off + dead_stats_off_delta); +- return sum; ++ bfqg_stats_reset(&bfqg->stats); + } + +-/* to be used by recursive prfill, sums live and dead rwstats recursively */ +-static struct blkg_rwstat bfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd, +- int off) ++static void bfq_group_set_parent(struct bfq_group *bfqg, ++ struct bfq_group *parent) + { +- struct blkg_rwstat a, b; +- +- a = blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off); +- b = blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, +- off + dead_stats_off_delta); +- blkg_rwstat_add_aux(&a, &b); +- return a; +-} ++ struct bfq_entity *entity; + +-static void bfq_pd_reset_stats(struct blkg_policy_data *pd) +-{ +- struct bfq_group *bfqg = pd_to_bfqg(pd); ++ BUG_ON(!parent); ++ BUG_ON(!bfqg); ++ BUG_ON(bfqg == parent); + +- bfqg_stats_reset(&bfqg->stats); +- bfqg_stats_reset(&bfqg->dead_stats); ++ entity = &bfqg->entity; ++ entity->parent = parent->my_entity; ++ entity->sched_data = &parent->sched_data; + } + + static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd, +@@ -531,13 +495,18 @@ static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd, + return bfqg; + } + +-static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq); ++static void bfq_pos_tree_add_move(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq); ++ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool compensate, ++ enum bfqq_expiration reason); + + /** + * bfq_bfqq_move - migrate @bfqq to @bfqg. + * @bfqd: queue descriptor. + * @bfqq: the queue to move. +- * @entity: @bfqq's entity. + * @bfqg: the group to move to. + * + * Move @bfqq to @bfqg, deactivating it from its old group and reactivating +@@ -548,26 +517,40 @@ static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) + * rcu_read_lock()). + */ + static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, +- struct bfq_entity *entity, struct bfq_group *bfqg) ++ struct bfq_group *bfqg) + { +- int busy, resume; ++ struct bfq_entity *entity = &bfqq->entity; + +- busy = bfq_bfqq_busy(bfqq); +- resume = !RB_EMPTY_ROOT(&bfqq->sort_list); +- +- BUG_ON(resume && !entity->on_st); +- BUG_ON(busy && !resume && entity->on_st && ++ BUG_ON(!bfq_bfqq_busy(bfqq) && !RB_EMPTY_ROOT(&bfqq->sort_list)); ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list) && !entity->on_st); ++ BUG_ON(bfq_bfqq_busy(bfqq) && RB_EMPTY_ROOT(&bfqq->sort_list) ++ && entity->on_st && + bfqq != bfqd->in_service_queue); ++ BUG_ON(!bfq_bfqq_busy(bfqq) && bfqq == bfqd->in_service_queue); ++ ++ /* If bfqq is empty, then bfq_bfqq_expire also invokes ++ * bfq_del_bfqq_busy, thereby removing bfqq and its entity ++ * from data structures related to current group. Otherwise we ++ * need to remove bfqq explicitly with bfq_deactivate_bfqq, as ++ * we do below. ++ */ ++ if (bfqq == bfqd->in_service_queue) ++ bfq_bfqq_expire(bfqd, bfqd->in_service_queue, ++ false, BFQ_BFQQ_PREEMPTED); ++ ++ BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq) ++ && &bfq_entity_service_tree(entity)->idle != ++ entity->tree); + +- if (busy) { +- BUG_ON(atomic_read(&bfqq->ref) < 2); ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq)); + +- if (!resume) +- bfq_del_bfqq_busy(bfqd, bfqq, 0); +- else +- bfq_deactivate_bfqq(bfqd, bfqq, 0); +- } else if (entity->on_st) ++ if (bfq_bfqq_busy(bfqq)) ++ bfq_deactivate_bfqq(bfqd, bfqq, 0); ++ else if (entity->on_st) { ++ BUG_ON(&bfq_entity_service_tree(entity)->idle != ++ entity->tree); + bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); ++ } + bfqg_put(bfqq_group(bfqq)); + + /* +@@ -579,14 +562,17 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, + entity->sched_data = &bfqg->sched_data; + bfqg_get(bfqg); + +- if (busy) { ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq)); ++ if (bfq_bfqq_busy(bfqq)) { + bfq_pos_tree_add_move(bfqd, bfqq); +- if (resume) +- bfq_activate_bfqq(bfqd, bfqq); ++ bfq_activate_bfqq(bfqd, bfqq); + } + + if (!bfqd->in_service_queue && !bfqd->rq_in_driver) + bfq_schedule_dispatch(bfqd); ++ BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq) ++ && &bfq_entity_service_tree(entity)->idle != ++ entity->tree); + } + + /** +@@ -621,7 +607,8 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, + bic_set_bfqq(bic, NULL, 0); + bfq_log_bfqq(bfqd, async_bfqq, + "bic_change_group: %p %d", +- async_bfqq, atomic_read(&async_bfqq->ref)); ++ async_bfqq, ++ async_bfqq->ref); + bfq_put_queue(async_bfqq); + } + } +@@ -629,7 +616,7 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, + if (sync_bfqq) { + entity = &sync_bfqq->entity; + if (entity->sched_data != &bfqg->sched_data) +- bfq_bfqq_move(bfqd, sync_bfqq, entity, bfqg); ++ bfq_bfqq_move(bfqd, sync_bfqq, bfqg); + } + + return bfqg; +@@ -638,25 +625,23 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, + static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) + { + struct bfq_data *bfqd = bic_to_bfqd(bic); +- struct blkcg *blkcg; + struct bfq_group *bfqg = NULL; +- uint64_t id; ++ uint64_t serial_nr; + + rcu_read_lock(); +- blkcg = bio_blkcg(bio); +- id = blkcg->css.serial_nr; +- rcu_read_unlock(); ++ serial_nr = bio_blkcg(bio)->css.serial_nr; + + /* + * Check whether blkcg has changed. The condition may trigger + * spuriously on a newly created cic but there's no harm. + */ +- if (unlikely(!bfqd) || likely(bic->blkcg_id == id)) +- return; ++ if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr)) ++ goto out; + +- bfqg = __bfq_bic_change_cgroup(bfqd, bic, blkcg); +- BUG_ON(!bfqg); +- bic->blkcg_id = id; ++ bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio)); ++ bic->blkcg_serial_nr = serial_nr; ++out: ++ rcu_read_unlock(); + } + + /** +@@ -682,8 +667,7 @@ static void bfq_reparent_leaf_entity(struct bfq_data *bfqd, + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + BUG_ON(!bfqq); +- bfq_bfqq_move(bfqd, bfqq, entity, bfqd->root_group); +- return; ++ bfq_bfqq_move(bfqd, bfqq, bfqd->root_group); + } + + /** +@@ -711,16 +695,15 @@ static void bfq_reparent_active_entities(struct bfq_data *bfqd, + if (bfqg->sched_data.in_service_entity) + bfq_reparent_leaf_entity(bfqd, + bfqg->sched_data.in_service_entity); +- +- return; + } + + /** +- * bfq_destroy_group - destroy @bfqg. +- * @bfqg: the group being destroyed. ++ * bfq_pd_offline - deactivate the entity associated with @pd, ++ * and reparent its children entities. ++ * @pd: descriptor of the policy going offline. + * +- * Destroy @bfqg, making sure that it is not referenced from its parent. +- * blkio already grabs the queue_lock for us, so no need to use RCU-based magic ++ * blkio already grabs the queue_lock for us, so no need to use ++ * RCU-based magic + */ + static void bfq_pd_offline(struct blkg_policy_data *pd) + { +@@ -779,6 +762,12 @@ static void bfq_pd_offline(struct blkg_policy_data *pd) + bfq_put_async_queues(bfqd, bfqg); + BUG_ON(entity->tree); + ++ /* ++ * @blkg is going offline and will be ignored by ++ * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so ++ * that they don't get lost. If IOs complete after this point, the ++ * stats for them will be lost. Oh well... ++ */ + bfqg_stats_xfer_dead(bfqg); + } + +@@ -788,46 +777,35 @@ static void bfq_end_wr_async(struct bfq_data *bfqd) + + list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) { + struct bfq_group *bfqg = blkg_to_bfqg(blkg); ++ BUG_ON(!bfqg); + + bfq_end_wr_async_queues(bfqd, bfqg); + } + bfq_end_wr_async_queues(bfqd, bfqd->root_group); + } + +-static u64 bfqio_cgroup_weight_read(struct cgroup_subsys_state *css, +- struct cftype *cftype) +-{ +- struct blkcg *blkcg = css_to_blkcg(css); +- struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); +- int ret = -EINVAL; +- +- spin_lock_irq(&blkcg->lock); +- ret = bfqgd->weight; +- spin_unlock_irq(&blkcg->lock); +- +- return ret; +-} +- +-static int bfqio_cgroup_weight_read_dfl(struct seq_file *sf, void *v) ++static int bfq_io_show_weight(struct seq_file *sf, void *v) + { + struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); + struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); ++ unsigned int val = 0; + +- spin_lock_irq(&blkcg->lock); +- seq_printf(sf, "%u\n", bfqgd->weight); +- spin_unlock_irq(&blkcg->lock); ++ if (bfqgd) ++ val = bfqgd->weight; ++ ++ seq_printf(sf, "%u\n", val); + + return 0; + } + +-static int bfqio_cgroup_weight_write(struct cgroup_subsys_state *css, +- struct cftype *cftype, +- u64 val) ++static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, ++ struct cftype *cftype, ++ u64 val) + { + struct blkcg *blkcg = css_to_blkcg(css); + struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); + struct blkcg_gq *blkg; +- int ret = -EINVAL; ++ int ret = -ERANGE; + + if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) + return ret; +@@ -837,6 +815,7 @@ static int bfqio_cgroup_weight_write(struct cgroup_subsys_state *css, + bfqgd->weight = (unsigned short)val; + hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { + struct bfq_group *bfqg = blkg_to_bfqg(blkg); ++ + if (!bfqg) + continue; + /* +@@ -871,13 +850,18 @@ static int bfqio_cgroup_weight_write(struct cgroup_subsys_state *css, + return ret; + } + +-static ssize_t bfqio_cgroup_weight_write_dfl(struct kernfs_open_file *of, +- char *buf, size_t nbytes, +- loff_t off) ++static ssize_t bfq_io_set_weight(struct kernfs_open_file *of, ++ char *buf, size_t nbytes, ++ loff_t off) + { ++ u64 weight; + /* First unsigned long found in the file is used */ +- return bfqio_cgroup_weight_write(of_css(of), NULL, +- simple_strtoull(strim(buf), NULL, 0)); ++ int ret = kstrtoull(strim(buf), 0, &weight); ++ ++ if (ret) ++ return ret; ++ ++ return bfq_io_set_weight_legacy(of_css(of), NULL, weight); + } + + static int bfqg_print_stat(struct seq_file *sf, void *v) +@@ -897,16 +881,17 @@ static int bfqg_print_rwstat(struct seq_file *sf, void *v) + static u64 bfqg_prfill_stat_recursive(struct seq_file *sf, + struct blkg_policy_data *pd, int off) + { +- u64 sum = bfqg_stat_pd_recursive_sum(pd, off); +- ++ u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd), ++ &blkcg_policy_bfq, off); + return __blkg_prfill_u64(sf, pd, sum); + } + + static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf, + struct blkg_policy_data *pd, int off) + { +- struct blkg_rwstat sum = bfqg_rwstat_pd_recursive_sum(pd, off); +- ++ struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd), ++ &blkcg_policy_bfq, ++ off); + return __blkg_prfill_rwstat(sf, pd, &sum); + } + +@@ -926,6 +911,41 @@ static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v) + return 0; + } + ++static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd, ++ int off) ++{ ++ u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes); ++ ++ return __blkg_prfill_u64(sf, pd, sum >> 9); ++} ++ ++static int bfqg_print_stat_sectors(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false); ++ return 0; ++} ++ ++static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf, ++ struct blkg_policy_data *pd, int off) ++{ ++ struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL, ++ offsetof(struct blkcg_gq, stat_bytes)); ++ u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) + ++ atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]); ++ ++ return __blkg_prfill_u64(sf, pd, sum >> 9); ++} ++ ++static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v) ++{ ++ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), ++ bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0, ++ false); ++ return 0; ++} ++ ++ + static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf, + struct blkg_policy_data *pd, int off) + { +@@ -950,7 +970,8 @@ static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v) + return 0; + } + +-static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) ++static struct bfq_group * ++bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) + { + int ret; + +@@ -958,41 +979,18 @@ static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int n + if (ret) + return NULL; + +- return blkg_to_bfqg(bfqd->queue->root_blkg); +-} +- +-static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp) +-{ +- struct bfq_group_data *bgd; +- +- bgd = kzalloc(sizeof(*bgd), GFP_KERNEL); +- if (!bgd) +- return NULL; +- return &bgd->pd; ++ return blkg_to_bfqg(bfqd->queue->root_blkg); + } + +-static void bfq_cpd_free(struct blkcg_policy_data *cpd) +-{ +- kfree(cpd_to_bfqgd(cpd)); +-} +- +-static struct cftype bfqio_files_dfl[] = { ++static struct cftype bfq_blkcg_legacy_files[] = { + { +- .name = "weight", ++ .name = "bfq.weight", + .flags = CFTYPE_NOT_ON_ROOT, +- .seq_show = bfqio_cgroup_weight_read_dfl, +- .write = bfqio_cgroup_weight_write_dfl, ++ .seq_show = bfq_io_show_weight, ++ .write_u64 = bfq_io_set_weight_legacy, + }, +- {} /* terminate */ +-}; + +-static struct cftype bfqio_files[] = { +- { +- .name = "bfq.weight", +- .read_u64 = bfqio_cgroup_weight_read, +- .write_u64 = bfqio_cgroup_weight_write, +- }, +- /* statistics, cover only the tasks in the bfqg */ ++ /* statistics, covers only the tasks in the bfqg */ + { + .name = "bfq.time", + .private = offsetof(struct bfq_group, stats.time), +@@ -1000,18 +998,17 @@ static struct cftype bfqio_files[] = { + }, + { + .name = "bfq.sectors", +- .private = offsetof(struct bfq_group, stats.sectors), +- .seq_show = bfqg_print_stat, ++ .seq_show = bfqg_print_stat_sectors, + }, + { + .name = "bfq.io_service_bytes", +- .private = offsetof(struct bfq_group, stats.service_bytes), +- .seq_show = bfqg_print_rwstat, ++ .private = (unsigned long)&blkcg_policy_bfq, ++ .seq_show = blkg_print_stat_bytes, + }, + { + .name = "bfq.io_serviced", +- .private = offsetof(struct bfq_group, stats.serviced), +- .seq_show = bfqg_print_rwstat, ++ .private = (unsigned long)&blkcg_policy_bfq, ++ .seq_show = blkg_print_stat_ios, + }, + { + .name = "bfq.io_service_time", +@@ -1042,18 +1039,17 @@ static struct cftype bfqio_files[] = { + }, + { + .name = "bfq.sectors_recursive", +- .private = offsetof(struct bfq_group, stats.sectors), +- .seq_show = bfqg_print_stat_recursive, ++ .seq_show = bfqg_print_stat_sectors_recursive, + }, + { + .name = "bfq.io_service_bytes_recursive", +- .private = offsetof(struct bfq_group, stats.service_bytes), +- .seq_show = bfqg_print_rwstat_recursive, ++ .private = (unsigned long)&blkcg_policy_bfq, ++ .seq_show = blkg_print_stat_bytes_recursive, + }, + { + .name = "bfq.io_serviced_recursive", +- .private = offsetof(struct bfq_group, stats.serviced), +- .seq_show = bfqg_print_rwstat_recursive, ++ .private = (unsigned long)&blkcg_policy_bfq, ++ .seq_show = blkg_print_stat_ios_recursive, + }, + { + .name = "bfq.io_service_time_recursive", +@@ -1099,32 +1095,35 @@ static struct cftype bfqio_files[] = { + .private = offsetof(struct bfq_group, stats.dequeue), + .seq_show = bfqg_print_stat, + }, +- { +- .name = "bfq.unaccounted_time", +- .private = offsetof(struct bfq_group, stats.unaccounted_time), +- .seq_show = bfqg_print_stat, +- }, + { } /* terminate */ + }; + +-static struct blkcg_policy blkcg_policy_bfq = { +- .dfl_cftypes = bfqio_files_dfl, +- .legacy_cftypes = bfqio_files, +- +- .pd_alloc_fn = bfq_pd_alloc, +- .pd_init_fn = bfq_pd_init, +- .pd_offline_fn = bfq_pd_offline, +- .pd_free_fn = bfq_pd_free, +- .pd_reset_stats_fn = bfq_pd_reset_stats, +- +- .cpd_alloc_fn = bfq_cpd_alloc, +- .cpd_init_fn = bfq_cpd_init, +- .cpd_bind_fn = bfq_cpd_init, +- .cpd_free_fn = bfq_cpd_free, +- ++static struct cftype bfq_blkg_files[] = { ++ { ++ .name = "bfq.weight", ++ .flags = CFTYPE_NOT_ON_ROOT, ++ .seq_show = bfq_io_show_weight, ++ .write = bfq_io_set_weight, ++ }, ++ {} /* terminate */ + }; + +-#else ++#else /* CONFIG_BFQ_GROUP_IOSCHED */ ++ ++static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg, ++ struct bfq_queue *bfqq, int rw) { } ++static inline void bfqg_stats_update_io_remove(struct bfq_group *bfqg, int rw) { } ++static inline void bfqg_stats_update_io_merged(struct bfq_group *bfqg, int rw) { } ++static inline void bfqg_stats_update_completion(struct bfq_group *bfqg, ++ uint64_t start_time, uint64_t io_start_time, int rw) { } ++static inline void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, ++struct bfq_group *curr_bfqg) { } ++static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { } ++static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { } ++static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { } ++static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { } ++static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { } ++static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { } + + static void bfq_init_entity(struct bfq_entity *entity, + struct bfq_group *bfqg) +@@ -1146,29 +1145,22 @@ bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) + return bfqd->root_group; + } + +-static void bfq_bfqq_move(struct bfq_data *bfqd, +- struct bfq_queue *bfqq, +- struct bfq_entity *entity, +- struct bfq_group *bfqg) +-{ +-} +- + static void bfq_end_wr_async(struct bfq_data *bfqd) + { + bfq_end_wr_async_queues(bfqd, bfqd->root_group); + } + +-static void bfq_disconnect_groups(struct bfq_data *bfqd) +-{ +- bfq_put_async_queues(bfqd, bfqd->root_group); +-} +- + static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd, + struct blkcg *blkcg) + { + return bfqd->root_group; + } + ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq) ++{ ++ return bfqq->bfqd->root_group; ++} ++ + static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) + { + struct bfq_group *bfqg; +diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c +index d1f648d..d1f3666 100644 +--- a/block/bfq-iosched.c ++++ b/block/bfq-iosched.c +@@ -7,25 +7,26 @@ + * Copyright (C) 2008 Fabio Checconi + * Paolo Valente + * +- * Copyright (C) 2010 Paolo Valente ++ * Copyright (C) 2016 Paolo Valente + * + * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ + * file. + * +- * BFQ is a proportional-share storage-I/O scheduling algorithm based on +- * the slice-by-slice service scheme of CFQ. But BFQ assigns budgets, +- * measured in number of sectors, to processes instead of time slices. The +- * device is not granted to the in-service process for a given time slice, +- * but until it has exhausted its assigned budget. This change from the time +- * to the service domain allows BFQ to distribute the device throughput +- * among processes as desired, without any distortion due to ZBR, workload +- * fluctuations or other factors. BFQ uses an ad hoc internal scheduler, +- * called B-WF2Q+, to schedule processes according to their budgets. More +- * precisely, BFQ schedules queues associated to processes. Thanks to the +- * accurate policy of B-WF2Q+, BFQ can afford to assign high budgets to +- * I/O-bound processes issuing sequential requests (to boost the +- * throughput), and yet guarantee a low latency to interactive and soft +- * real-time applications. ++ * BFQ is a proportional-share storage-I/O scheduling algorithm based ++ * on the slice-by-slice service scheme of CFQ. But BFQ assigns ++ * budgets, measured in number of sectors, to processes instead of ++ * time slices. The device is not granted to the in-service process ++ * for a given time slice, but until it has exhausted its assigned ++ * budget. This change from the time to the service domain enables BFQ ++ * to distribute the device throughput among processes as desired, ++ * without any distortion due to throughput fluctuations, or to device ++ * internal queueing. BFQ uses an ad hoc internal scheduler, called ++ * B-WF2Q+, to schedule processes according to their budgets. More ++ * precisely, BFQ schedules queues associated with processes. Thanks to ++ * the accurate policy of B-WF2Q+, BFQ can afford to assign high ++ * budgets to I/O-bound processes issuing sequential requests (to ++ * boost the throughput), and yet guarantee a low latency to ++ * interactive and soft real-time applications. + * + * BFQ is described in [1], where also a reference to the initial, more + * theoretical paper on BFQ can be found. The interested reader can find +@@ -87,7 +88,6 @@ static const int bfq_stats_min_budgets = 194; + + /* Default maximum budget values, in sectors and number of requests. */ + static const int bfq_default_max_budget = 16 * 1024; +-static const int bfq_max_budget_async_rq = 4; + + /* + * Async to sync throughput distribution is controlled as follows: +@@ -97,8 +97,7 @@ static const int bfq_max_budget_async_rq = 4; + static const int bfq_async_charge_factor = 10; + + /* Default timeout values, in jiffies, approximating CFQ defaults. */ +-static const int bfq_timeout_sync = HZ / 8; +-static int bfq_timeout_async = HZ / 25; ++static const int bfq_timeout = HZ / 8; + + struct kmem_cache *bfq_pool; + +@@ -109,8 +108,9 @@ struct kmem_cache *bfq_pool; + #define BFQ_HW_QUEUE_THRESHOLD 4 + #define BFQ_HW_QUEUE_SAMPLES 32 + +-#define BFQQ_SEEK_THR (sector_t)(8 * 1024) +-#define BFQQ_SEEKY(bfqq) ((bfqq)->seek_mean > BFQQ_SEEK_THR) ++#define BFQQ_SEEK_THR (sector_t)(8 * 100) ++#define BFQQ_CLOSE_THR (sector_t)(8 * 1024) ++#define BFQQ_SEEKY(bfqq) (hweight32(bfqq->seek_history) > 32/8) + + /* Min samples used for peak rate estimation (for autotuning). */ + #define BFQ_PEAK_RATE_SAMPLES 32 +@@ -141,16 +141,24 @@ struct kmem_cache *bfq_pool; + * The device's speed class is dynamically (re)detected in + * bfq_update_peak_rate() every time the estimated peak rate is updated. + * +- * In the following definitions, R_slow[0]/R_fast[0] and T_slow[0]/T_fast[0] +- * are the reference values for a slow/fast rotational device, whereas +- * R_slow[1]/R_fast[1] and T_slow[1]/T_fast[1] are the reference values for +- * a slow/fast non-rotational device. Finally, device_speed_thresh are the +- * thresholds used to switch between speed classes. ++ * In the following definitions, R_slow[0]/R_fast[0] and ++ * T_slow[0]/T_fast[0] are the reference values for a slow/fast ++ * rotational device, whereas R_slow[1]/R_fast[1] and ++ * T_slow[1]/T_fast[1] are the reference values for a slow/fast ++ * non-rotational device. Finally, device_speed_thresh are the ++ * thresholds used to switch between speed classes. The reference ++ * rates are not the actual peak rates of the devices used as a ++ * reference, but slightly lower values. The reason for using these ++ * slightly lower values is that the peak-rate estimator tends to ++ * yield slightly lower values than the actual peak rate (it can yield ++ * the actual peak rate only if there is only one process doing I/O, ++ * and the process does sequential I/O). ++ * + * Both the reference peak rates and the thresholds are measured in + * sectors/usec, left-shifted by BFQ_RATE_SHIFT. + */ +-static int R_slow[2] = {1536, 10752}; +-static int R_fast[2] = {17415, 34791}; ++static int R_slow[2] = {1000, 10700}; ++static int R_fast[2] = {14000, 33000}; + /* + * To improve readability, a conversion function is used to initialize the + * following arrays, which entails that they can be initialized only in a +@@ -410,11 +418,7 @@ static bool bfq_differentiated_weights(struct bfq_data *bfqd) + */ + static bool bfq_symmetric_scenario(struct bfq_data *bfqd) + { +- return +-#ifdef CONFIG_BFQ_GROUP_IOSCHED +- !bfqd->active_numerous_groups && +-#endif +- !bfq_differentiated_weights(bfqd); ++ return !bfq_differentiated_weights(bfqd); + } + + /* +@@ -534,9 +538,19 @@ static struct request *bfq_find_next_rq(struct bfq_data *bfqd, + static unsigned long bfq_serv_to_charge(struct request *rq, + struct bfq_queue *bfqq) + { +- return blk_rq_sectors(rq) * +- (1 + ((!bfq_bfqq_sync(bfqq)) * (bfqq->wr_coeff == 1) * +- bfq_async_charge_factor)); ++ if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1) ++ return blk_rq_sectors(rq); ++ ++ /* ++ * If there are no weight-raised queues, then amplify service ++ * by just the async charge factor; otherwise amplify service ++ * by twice the async charge factor, to further reduce latency ++ * for weight-raised queues. ++ */ ++ if (bfqq->bfqd->wr_busy_queues == 0) ++ return blk_rq_sectors(rq) * bfq_async_charge_factor; ++ ++ return blk_rq_sectors(rq) * 2 * bfq_async_charge_factor; + } + + /** +@@ -591,12 +605,23 @@ static unsigned int bfq_wr_duration(struct bfq_data *bfqd) + dur = bfqd->RT_prod; + do_div(dur, bfqd->peak_rate); + +- return dur; +-} ++ /* ++ * Limit duration between 3 and 13 seconds. Tests show that ++ * higher values than 13 seconds often yield the opposite of ++ * the desired result, i.e., worsen responsiveness by letting ++ * non-interactive and non-soft-real-time applications ++ * preserve weight raising for a too long time interval. ++ * ++ * On the other end, lower values than 3 seconds make it ++ * difficult for most interactive tasks to complete their jobs ++ * before weight-raising finishes. ++ */ ++ if (dur > msecs_to_jiffies(13000)) ++ dur = msecs_to_jiffies(13000); ++ else if (dur < msecs_to_jiffies(3000)) ++ dur = msecs_to_jiffies(3000); + +-static unsigned bfq_bfqq_cooperations(struct bfq_queue *bfqq) +-{ +- return bfqq->bic ? bfqq->bic->cooperations : 0; ++ return dur; + } + + static void +@@ -606,31 +631,11 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic) + bfq_mark_bfqq_idle_window(bfqq); + else + bfq_clear_bfqq_idle_window(bfqq); ++ + if (bic->saved_IO_bound) + bfq_mark_bfqq_IO_bound(bfqq); + else + bfq_clear_bfqq_IO_bound(bfqq); +- /* Assuming that the flag in_large_burst is already correctly set */ +- if (bic->wr_time_left && bfqq->bfqd->low_latency && +- !bfq_bfqq_in_large_burst(bfqq) && +- bic->cooperations < bfqq->bfqd->bfq_coop_thresh) { +- /* +- * Start a weight raising period with the duration given by +- * the raising_time_left snapshot. +- */ +- if (bfq_bfqq_busy(bfqq)) +- bfqq->bfqd->wr_busy_queues++; +- bfqq->wr_coeff = bfqq->bfqd->bfq_wr_coeff; +- bfqq->wr_cur_max_time = bic->wr_time_left; +- bfqq->last_wr_start_finish = jiffies; +- bfqq->entity.prio_changed = 1; +- } +- /* +- * Clear wr_time_left to prevent bfq_bfqq_save_state() from +- * getting confused about the queue's need of a weight-raising +- * period. +- */ +- bic->wr_time_left = 0; + } + + static int bfqq_process_refs(struct bfq_queue *bfqq) +@@ -640,7 +645,7 @@ static int bfqq_process_refs(struct bfq_queue *bfqq) + lockdep_assert_held(bfqq->bfqd->queue->queue_lock); + + io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE]; +- process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st; ++ process_refs = bfqq->ref - io_refs - bfqq->entity.on_st; + BUG_ON(process_refs < 0); + return process_refs; + } +@@ -655,6 +660,7 @@ static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq) + hlist_del_init(&item->burst_list_node); + hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); + bfqd->burst_size = 1; ++ bfqd->burst_parent_entity = bfqq->entity.parent; + } + + /* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */ +@@ -663,6 +669,10 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) + /* Increment burst size to take into account also bfqq */ + bfqd->burst_size++; + ++ bfq_log_bfqq(bfqd, bfqq, "add_to_burst %d", bfqd->burst_size); ++ ++ BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh); ++ + if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) { + struct bfq_queue *pos, *bfqq_item; + struct hlist_node *n; +@@ -672,15 +682,19 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) + * other to consider this burst as large. + */ + bfqd->large_burst = true; ++ bfq_log_bfqq(bfqd, bfqq, "add_to_burst: large burst started"); + + /* + * We can now mark all queues in the burst list as + * belonging to a large burst. + */ + hlist_for_each_entry(bfqq_item, &bfqd->burst_list, +- burst_list_node) ++ burst_list_node) { + bfq_mark_bfqq_in_large_burst(bfqq_item); ++ bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst"); ++ } + bfq_mark_bfqq_in_large_burst(bfqq); ++ bfq_log_bfqq(bfqd, bfqq, "marked in large burst"); + + /* + * From now on, and until the current burst finishes, any +@@ -692,67 +706,79 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) + hlist_for_each_entry_safe(pos, n, &bfqd->burst_list, + burst_list_node) + hlist_del_init(&pos->burst_list_node); +- } else /* burst not yet large: add bfqq to the burst list */ ++ } else /* ++ * Burst not yet large: add bfqq to the burst list. Do ++ * not increment the ref counter for bfqq, because bfqq ++ * is removed from the burst list before freeing bfqq ++ * in put_queue. ++ */ + hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); + } + + /* +- * If many queues happen to become active shortly after each other, then, +- * to help the processes associated to these queues get their job done as +- * soon as possible, it is usually better to not grant either weight-raising +- * or device idling to these queues. In this comment we describe, firstly, +- * the reasons why this fact holds, and, secondly, the next function, which +- * implements the main steps needed to properly mark these queues so that +- * they can then be treated in a different way. ++ * If many queues belonging to the same group happen to be created ++ * shortly after each other, then the processes associated with these ++ * queues have typically a common goal. In particular, bursts of queue ++ * creations are usually caused by services or applications that spawn ++ * many parallel threads/processes. Examples are systemd during boot, ++ * or git grep. To help these processes get their job done as soon as ++ * possible, it is usually better to not grant either weight-raising ++ * or device idling to their queues. + * +- * As for the terminology, we say that a queue becomes active, i.e., +- * switches from idle to backlogged, either when it is created (as a +- * consequence of the arrival of an I/O request), or, if already existing, +- * when a new request for the queue arrives while the queue is idle. +- * Bursts of activations, i.e., activations of different queues occurring +- * shortly after each other, are typically caused by services or applications +- * that spawn or reactivate many parallel threads/processes. Examples are +- * systemd during boot or git grep. ++ * In this comment we describe, firstly, the reasons why this fact ++ * holds, and, secondly, the next function, which implements the main ++ * steps needed to properly mark these queues so that they can then be ++ * treated in a different way. + * +- * These services or applications benefit mostly from a high throughput: +- * the quicker the requests of the activated queues are cumulatively served, +- * the sooner the target job of these queues gets completed. As a consequence, +- * weight-raising any of these queues, which also implies idling the device +- * for it, is almost always counterproductive: in most cases it just lowers +- * throughput. ++ * The above services or applications benefit mostly from a high ++ * throughput: the quicker the requests of the activated queues are ++ * cumulatively served, the sooner the target job of these queues gets ++ * completed. As a consequence, weight-raising any of these queues, ++ * which also implies idling the device for it, is almost always ++ * counterproductive. In most cases it just lowers throughput. + * +- * On the other hand, a burst of activations may be also caused by the start +- * of an application that does not consist in a lot of parallel I/O-bound +- * threads. In fact, with a complex application, the burst may be just a +- * consequence of the fact that several processes need to be executed to +- * start-up the application. To start an application as quickly as possible, +- * the best thing to do is to privilege the I/O related to the application +- * with respect to all other I/O. Therefore, the best strategy to start as +- * quickly as possible an application that causes a burst of activations is +- * to weight-raise all the queues activated during the burst. This is the ++ * On the other hand, a burst of queue creations may be caused also by ++ * the start of an application that does not consist of a lot of ++ * parallel I/O-bound threads. In fact, with a complex application, ++ * several short processes may need to be executed to start-up the ++ * application. In this respect, to start an application as quickly as ++ * possible, the best thing to do is in any case to privilege the I/O ++ * related to the application with respect to all other ++ * I/O. Therefore, the best strategy to start as quickly as possible ++ * an application that causes a burst of queue creations is to ++ * weight-raise all the queues created during the burst. This is the + * exact opposite of the best strategy for the other type of bursts. + * +- * In the end, to take the best action for each of the two cases, the two +- * types of bursts need to be distinguished. Fortunately, this seems +- * relatively easy to do, by looking at the sizes of the bursts. In +- * particular, we found a threshold such that bursts with a larger size +- * than that threshold are apparently caused only by services or commands +- * such as systemd or git grep. For brevity, hereafter we call just 'large' +- * these bursts. BFQ *does not* weight-raise queues whose activations occur +- * in a large burst. In addition, for each of these queues BFQ performs or +- * does not perform idling depending on which choice boosts the throughput +- * most. The exact choice depends on the device and request pattern at ++ * In the end, to take the best action for each of the two cases, the ++ * two types of bursts need to be distinguished. Fortunately, this ++ * seems relatively easy, by looking at the sizes of the bursts. In ++ * particular, we found a threshold such that only bursts with a ++ * larger size than that threshold are apparently caused by ++ * services or commands such as systemd or git grep. For brevity, ++ * hereafter we call just 'large' these bursts. BFQ *does not* ++ * weight-raise queues whose creation occurs in a large burst. In ++ * addition, for each of these queues BFQ performs or does not perform ++ * idling depending on which choice boosts the throughput more. The ++ * exact choice depends on the device and request pattern at + * hand. + * +- * Turning back to the next function, it implements all the steps needed +- * to detect the occurrence of a large burst and to properly mark all the +- * queues belonging to it (so that they can then be treated in a different +- * way). This goal is achieved by maintaining a special "burst list" that +- * holds, temporarily, the queues that belong to the burst in progress. The +- * list is then used to mark these queues as belonging to a large burst if +- * the burst does become large. The main steps are the following. ++ * Unfortunately, false positives may occur while an interactive task ++ * is starting (e.g., an application is being started). The ++ * consequence is that the queues associated with the task do not ++ * enjoy weight raising as expected. Fortunately these false positives ++ * are very rare. They typically occur if some service happens to ++ * start doing I/O exactly when the interactive task starts. ++ * ++ * Turning back to the next function, it implements all the steps ++ * needed to detect the occurrence of a large burst and to properly ++ * mark all the queues belonging to it (so that they can then be ++ * treated in a different way). This goal is achieved by maintaining a ++ * "burst list" that holds, temporarily, the queues that belong to the ++ * burst in progress. The list is then used to mark these queues as ++ * belonging to a large burst if the burst does become large. The main ++ * steps are the following. + * +- * . when the very first queue is activated, the queue is inserted into the ++ * . when the very first queue is created, the queue is inserted into the + * list (as it could be the first queue in a possible burst) + * + * . if the current burst has not yet become large, and a queue Q that does +@@ -773,13 +799,13 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) + * + * . the device enters a large-burst mode + * +- * . if a queue Q that does not belong to the burst is activated while ++ * . if a queue Q that does not belong to the burst is created while + * the device is in large-burst mode and shortly after the last time + * at which a queue either entered the burst list or was marked as + * belonging to the current large burst, then Q is immediately marked + * as belonging to a large burst. + * +- * . if a queue Q that does not belong to the burst is activated a while ++ * . if a queue Q that does not belong to the burst is created a while + * later, i.e., not shortly after, than the last time at which a queue + * either entered the burst list or was marked as belonging to the + * current large burst, then the current burst is deemed as finished and: +@@ -792,52 +818,44 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) + * in a possible new burst (then the burst list contains just Q + * after this step). + */ +-static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq, +- bool idle_for_long_time) ++static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) + { + /* +- * If bfqq happened to be activated in a burst, but has been idle +- * for at least as long as an interactive queue, then we assume +- * that, in the overall I/O initiated in the burst, the I/O +- * associated to bfqq is finished. So bfqq does not need to be +- * treated as a queue belonging to a burst anymore. Accordingly, +- * we reset bfqq's in_large_burst flag if set, and remove bfqq +- * from the burst list if it's there. We do not decrement instead +- * burst_size, because the fact that bfqq does not need to belong +- * to the burst list any more does not invalidate the fact that +- * bfqq may have been activated during the current burst. +- */ +- if (idle_for_long_time) { +- hlist_del_init(&bfqq->burst_list_node); +- bfq_clear_bfqq_in_large_burst(bfqq); +- } +- +- /* + * If bfqq is already in the burst list or is part of a large +- * burst, then there is nothing else to do. ++ * burst, or finally has just been split, then there is ++ * nothing else to do. + */ + if (!hlist_unhashed(&bfqq->burst_list_node) || +- bfq_bfqq_in_large_burst(bfqq)) ++ bfq_bfqq_in_large_burst(bfqq) || ++ time_is_after_eq_jiffies(bfqq->split_time + ++ msecs_to_jiffies(10))) + return; + + /* +- * If bfqq's activation happens late enough, then the current +- * burst is finished, and related data structures must be reset. ++ * If bfqq's creation happens late enough, or bfqq belongs to ++ * a different group than the burst group, then the current ++ * burst is finished, and related data structures must be ++ * reset. + * +- * In this respect, consider the special case where bfqq is the very +- * first queue being activated. In this case, last_ins_in_burst is +- * not yet significant when we get here. But it is easy to verify +- * that, whether or not the following condition is true, bfqq will +- * end up being inserted into the burst list. In particular the +- * list will happen to contain only bfqq. And this is exactly what +- * has to happen, as bfqq may be the first queue in a possible ++ * In this respect, consider the special case where bfqq is ++ * the very first queue created after BFQ is selected for this ++ * device. In this case, last_ins_in_burst and ++ * burst_parent_entity are not yet significant when we get ++ * here. But it is easy to verify that, whether or not the ++ * following condition is true, bfqq will end up being ++ * inserted into the burst list. In particular the list will ++ * happen to contain only bfqq. And this is exactly what has ++ * to happen, as bfqq may be the first queue of the first + * burst. + */ + if (time_is_before_jiffies(bfqd->last_ins_in_burst + +- bfqd->bfq_burst_interval)) { ++ bfqd->bfq_burst_interval) || ++ bfqq->entity.parent != bfqd->burst_parent_entity) { + bfqd->large_burst = false; + bfq_reset_burst_list(bfqd, bfqq); +- return; ++ bfq_log_bfqq(bfqd, bfqq, ++ "handle_burst: late activation or different group"); ++ goto end; + } + + /* +@@ -846,8 +864,9 @@ static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq, + * bfqq as belonging to this large burst immediately. + */ + if (bfqd->large_burst) { ++ bfq_log_bfqq(bfqd, bfqq, "handle_burst: marked in burst"); + bfq_mark_bfqq_in_large_burst(bfqq); +- return; ++ goto end; + } + + /* +@@ -856,25 +875,492 @@ static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq, + * queue. Then we add bfqq to the burst. + */ + bfq_add_to_burst(bfqd, bfqq); ++end: ++ /* ++ * At this point, bfqq either has been added to the current ++ * burst or has caused the current burst to terminate and a ++ * possible new burst to start. In particular, in the second ++ * case, bfqq has become the first queue in the possible new ++ * burst. In both cases last_ins_in_burst needs to be moved ++ * forward. ++ */ ++ bfqd->last_ins_in_burst = jiffies; ++ ++} ++ ++static int bfq_bfqq_budget_left(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ return entity->budget - entity->service; ++} ++ ++/* ++ * If enough samples have been computed, return the current max budget ++ * stored in bfqd, which is dynamically updated according to the ++ * estimated disk peak rate; otherwise return the default max budget ++ */ ++static int bfq_max_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < bfq_stats_min_budgets) ++ return bfq_default_max_budget; ++ else ++ return bfqd->bfq_max_budget; ++} ++ ++/* ++ * Return min budget, which is a fraction of the current or default ++ * max budget (trying with 1/32) ++ */ ++static int bfq_min_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < bfq_stats_min_budgets) ++ return bfq_default_max_budget / 32; ++ else ++ return bfqd->bfq_max_budget / 32; ++} ++ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool compensate, ++ enum bfqq_expiration reason); ++ ++/* ++ * The next function, invoked after the input queue bfqq switches from ++ * idle to busy, updates the budget of bfqq. The function also tells ++ * whether the in-service queue should be expired, by returning ++ * true. The purpose of expiring the in-service queue is to give bfqq ++ * the chance to possibly preempt the in-service queue, and the reason ++ * for preempting the in-service queue is to achieve one of the two ++ * goals below. ++ * ++ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has ++ * expired because it has remained idle. In particular, bfqq may have ++ * expired for one of the following two reasons: ++ * ++ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and ++ * did not make it to issue a new request before its last request ++ * was served; ++ * ++ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue ++ * a new request before the expiration of the idling-time. ++ * ++ * Even if bfqq has expired for one of the above reasons, the process ++ * associated with the queue may be however issuing requests greedily, ++ * and thus be sensitive to the bandwidth it receives (bfqq may have ++ * remained idle for other reasons: CPU high load, bfqq not enjoying ++ * idling, I/O throttling somewhere in the path from the process to ++ * the I/O scheduler, ...). But if, after every expiration for one of ++ * the above two reasons, bfqq has to wait for the service of at least ++ * one full budget of another queue before being served again, then ++ * bfqq is likely to get a much lower bandwidth or resource time than ++ * its reserved ones. To address this issue, two countermeasures need ++ * to be taken. ++ * ++ * First, the budget and the timestamps of bfqq need to be updated in ++ * a special way on bfqq reactivation: they need to be updated as if ++ * bfqq did not remain idle and did not expire. In fact, if they are ++ * computed as if bfqq expired and remained idle until reactivation, ++ * then the process associated with bfqq is treated as if, instead of ++ * being greedy, it stopped issuing requests when bfqq remained idle, ++ * and restarts issuing requests only on this reactivation. In other ++ * words, the scheduler does not help the process recover the "service ++ * hole" between bfqq expiration and reactivation. As a consequence, ++ * the process receives a lower bandwidth than its reserved one. In ++ * contrast, to recover this hole, the budget must be updated as if ++ * bfqq was not expired at all before this reactivation, i.e., it must ++ * be set to the value of the remaining budget when bfqq was ++ * expired. Along the same line, timestamps need to be assigned the ++ * value they had the last time bfqq was selected for service, i.e., ++ * before last expiration. Thus timestamps need to be back-shifted ++ * with respect to their normal computation (see [1] for more details ++ * on this tricky aspect). ++ * ++ * Secondly, to allow the process to recover the hole, the in-service ++ * queue must be expired too, to give bfqq the chance to preempt it ++ * immediately. In fact, if bfqq has to wait for a full budget of the ++ * in-service queue to be completed, then it may become impossible to ++ * let the process recover the hole, even if the back-shifted ++ * timestamps of bfqq are lower than those of the in-service queue. If ++ * this happens for most or all of the holes, then the process may not ++ * receive its reserved bandwidth. In this respect, it is worth noting ++ * that, being the service of outstanding requests unpreemptible, a ++ * little fraction of the holes may however be unrecoverable, thereby ++ * causing a little loss of bandwidth. ++ * ++ * The last important point is detecting whether bfqq does need this ++ * bandwidth recovery. In this respect, the next function deems the ++ * process associated with bfqq greedy, and thus allows it to recover ++ * the hole, if: 1) the process is waiting for the arrival of a new ++ * request (which implies that bfqq expired for one of the above two ++ * reasons), and 2) such a request has arrived soon. The first ++ * condition is controlled through the flag non_blocking_wait_rq, ++ * while the second through the flag arrived_in_time. If both ++ * conditions hold, then the function computes the budget in the ++ * above-described special way, and signals that the in-service queue ++ * should be expired. Timestamp back-shifting is done later in ++ * __bfq_activate_entity. ++ * ++ * 2. Reduce latency. Even if timestamps are not backshifted to let ++ * the process associated with bfqq recover a service hole, bfqq may ++ * however happen to have, after being (re)activated, a lower finish ++ * timestamp than the in-service queue. That is, the next budget of ++ * bfqq may have to be completed before the one of the in-service ++ * queue. If this is the case, then preempting the in-service queue ++ * allows this goal to be achieved, apart from the unpreemptible, ++ * outstanding requests mentioned above. ++ * ++ * Unfortunately, regardless of which of the above two goals one wants ++ * to achieve, service trees need first to be updated to know whether ++ * the in-service queue must be preempted. To have service trees ++ * correctly updated, the in-service queue must be expired and ++ * rescheduled, and bfqq must be scheduled too. This is one of the ++ * most costly operations (in future versions, the scheduling ++ * mechanism may be re-designed in such a way to make it possible to ++ * know whether preemption is needed without needing to update service ++ * trees). In addition, queue preemptions almost always cause random ++ * I/O, and thus loss of throughput. Because of these facts, the next ++ * function adopts the following simple scheme to avoid both costly ++ * operations and too frequent preemptions: it requests the expiration ++ * of the in-service queue (unconditionally) only for queues that need ++ * to recover a hole, or that either are weight-raised or deserve to ++ * be weight-raised. ++ */ ++static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ bool arrived_in_time, ++ bool wr_or_deserves_wr) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time) { ++ /* ++ * We do not clear the flag non_blocking_wait_rq here, as ++ * the latter is used in bfq_activate_bfqq to signal ++ * that timestamps need to be back-shifted (and is ++ * cleared right after). ++ */ ++ ++ /* ++ * In next assignment we rely on that either ++ * entity->service or entity->budget are not updated ++ * on expiration if bfqq is empty (see ++ * __bfq_bfqq_recalc_budget). Thus both quantities ++ * remain unchanged after such an expiration, and the ++ * following statement therefore assigns to ++ * entity->budget the remaining budget on such an ++ * expiration. For clarity, entity->service is not ++ * updated on expiration in any case, and, in normal ++ * operation, is reset only when bfqq is selected for ++ * service (see bfq_get_next_queue). ++ */ ++ entity->budget = min_t(unsigned long, ++ bfq_bfqq_budget_left(bfqq), ++ bfqq->max_budget); ++ ++ BUG_ON(entity->budget < 0); ++ return true; ++ } ++ ++ entity->budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(bfqq->next_rq,bfqq)); ++ BUG_ON(entity->budget < 0); ++ ++ bfq_clear_bfqq_non_blocking_wait_rq(bfqq); ++ return wr_or_deserves_wr; ++} ++ ++static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ unsigned int old_wr_coeff, ++ bool wr_or_deserves_wr, ++ bool interactive, ++ bool in_burst, ++ bool soft_rt) ++{ ++ if (old_wr_coeff == 1 && wr_or_deserves_wr) { ++ /* start a weight-raising period */ ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ if (interactive) /* update wr duration */ ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ else ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ /* ++ * If needed, further reduce budget to make sure it is ++ * close to bfqq's backlog, so as to reduce the ++ * scheduling-error component due to a too large ++ * budget. Do not care about throughput consequences, ++ * but only about latency. Finally, do not assign a ++ * too small budget either, to avoid increasing ++ * latency by causing too frequent expirations. ++ */ ++ bfqq->entity.budget = min_t(unsigned long, ++ bfqq->entity.budget, ++ 2 * bfq_min_budget(bfqd)); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais starting at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } else if (old_wr_coeff > 1) { ++ if (interactive) /* update wr duration */ ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ else if (in_burst) { ++ bfqq->wr_coeff = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq-> ++ wr_cur_max_time)); ++ } else if (time_before( ++ bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time, ++ jiffies + ++ bfqd->bfq_wr_rt_max_time) && ++ soft_rt) { ++ /* ++ * The remaining weight-raising time is lower ++ * than bfqd->bfq_wr_rt_max_time, which means ++ * that the application is enjoying weight ++ * raising either because deemed soft-rt in ++ * the near past, or because deemed interactive ++ * a long ago. ++ * In both cases, resetting now the current ++ * remaining weight-raising time for the ++ * application to the weight-raising duration ++ * for soft rt applications would not cause any ++ * latency increase for the application (as the ++ * new duration would be higher than the ++ * remaining time). ++ * ++ * In addition, the application is now meeting ++ * the requirements for being deemed soft rt. ++ * In the end we can correctly and safely ++ * (re)charge the weight-raising duration for ++ * the application with the weight-raising ++ * duration for soft rt applications. ++ * ++ * In particular, doing this recharge now, i.e., ++ * before the weight-raising period for the ++ * application finishes, reduces the probability ++ * of the following negative scenario: ++ * 1) the weight of a soft rt application is ++ * raised at startup (as for any newly ++ * created application), ++ * 2) since the application is not interactive, ++ * at a certain time weight-raising is ++ * stopped for the application, ++ * 3) at that time the application happens to ++ * still have pending requests, and hence ++ * is destined to not have a chance to be ++ * deemed soft rt before these requests are ++ * completed (see the comments to the ++ * function bfq_bfqq_softrt_next_start() ++ * for details on soft rt detection), ++ * 4) these pending requests experience a high ++ * latency because the application is not ++ * weight-raised while they are pending. ++ */ ++ bfqq->last_wr_start_finish = jiffies; ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ bfq_log_bfqq(bfqd, bfqq, ++ "switching to soft_rt wr, or " ++ " just moving forward duration"); ++ } ++ } ++} ++ ++static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ return bfqq->dispatched == 0 && ++ time_is_before_jiffies( ++ bfqq->budget_timeout + ++ bfqd->bfq_wr_min_idle_time); ++} ++ ++static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ int old_wr_coeff, ++ struct request *rq, ++ bool *interactive) ++{ ++ bool soft_rt, in_burst, wr_or_deserves_wr, ++ bfqq_wants_to_preempt, ++ idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq), ++ /* ++ * See the comments on ++ * bfq_bfqq_update_budg_for_activation for ++ * details on the usage of the next variable. ++ */ ++ arrived_in_time = time_is_after_jiffies( ++ RQ_BIC(rq)->ttime.last_end_request + ++ bfqd->bfq_slice_idle * 3); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "bfq_add_request non-busy: " ++ "jiffies %lu, in_time %d, idle_long %d busyw %d " ++ "wr_coeff %u", ++ jiffies, arrived_in_time, ++ idle_for_long_time, ++ bfq_bfqq_non_blocking_wait_rq(bfqq), ++ old_wr_coeff); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, ++ rq->cmd_flags); ++ ++ /* ++ * bfqq deserves to be weight-raised if: ++ * - it is sync, ++ * - it does not belong to a large burst, ++ * - it has been idle for enough time or is soft real-time, ++ * - is linked to a bfq_io_cq (it is not shared in any sense) ++ */ ++ in_burst = bfq_bfqq_in_large_burst(bfqq); ++ soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && ++ !in_burst && ++ time_is_before_jiffies(bfqq->soft_rt_next_start); ++ *interactive = ++ !in_burst && ++ idle_for_long_time; ++ wr_or_deserves_wr = bfqd->low_latency && ++ (bfqq->wr_coeff > 1 || ++ (bfq_bfqq_sync(bfqq) && ++ bfqq->bic && (*interactive || soft_rt))); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "bfq_add_request: " ++ "in_burst %d, " ++ "soft_rt %d (next %lu), inter %d, bic %p", ++ bfq_bfqq_in_large_burst(bfqq), soft_rt, ++ bfqq->soft_rt_next_start, ++ *interactive, ++ bfqq->bic); ++ ++ /* ++ * Using the last flag, update budget and check whether bfqq ++ * may want to preempt the in-service queue. ++ */ ++ bfqq_wants_to_preempt = ++ bfq_bfqq_update_budg_for_activation(bfqd, bfqq, ++ arrived_in_time, ++ wr_or_deserves_wr); ++ ++ /* ++ * If bfqq happened to be activated in a burst, but has been ++ * idle for much more than an interactive queue, then we ++ * assume that, in the overall I/O initiated in the burst, the ++ * I/O associated with bfqq is finished. So bfqq does not need ++ * to be treated as a queue belonging to a burst ++ * anymore. Accordingly, we reset bfqq's in_large_burst flag ++ * if set, and remove bfqq from the burst list if it's ++ * there. We do not decrement burst_size, because the fact ++ * that bfqq does not need to belong to the burst list any ++ * more does not invalidate the fact that bfqq was created in ++ * a burst. ++ */ ++ if (likely(!bfq_bfqq_just_created(bfqq)) && ++ idle_for_long_time && ++ time_is_before_jiffies( ++ bfqq->budget_timeout + ++ msecs_to_jiffies(10000))) { ++ hlist_del_init(&bfqq->burst_list_node); ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ } ++ ++ bfq_clear_bfqq_just_created(bfqq); ++ ++ if (!bfq_bfqq_IO_bound(bfqq)) { ++ if (arrived_in_time) { ++ bfqq->requests_within_timer++; ++ if (bfqq->requests_within_timer >= ++ bfqd->bfq_requests_within_timer) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ } else ++ bfqq->requests_within_timer = 0; ++ bfq_log_bfqq(bfqd, bfqq, "requests in time %d", ++ bfqq->requests_within_timer); ++ } ++ ++ if (bfqd->low_latency) { ++ if (unlikely(time_is_after_jiffies(bfqq->split_time))) ++ /* wraparound */ ++ bfqq->split_time = ++ jiffies - bfqd->bfq_wr_min_idle_time - 1; ++ ++ if (time_is_before_jiffies(bfqq->split_time + ++ bfqd->bfq_wr_min_idle_time)) { ++ bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq, ++ old_wr_coeff, ++ wr_or_deserves_wr, ++ *interactive, ++ in_burst, ++ soft_rt); ++ ++ if (old_wr_coeff != bfqq->wr_coeff) ++ bfqq->entity.prio_changed = 1; ++ } ++ } ++ ++ bfqq->last_idle_bklogged = jiffies; ++ bfqq->service_from_backlogged = 0; ++ bfq_clear_bfqq_softrt_update(bfqq); ++ ++ bfq_add_bfqq_busy(bfqd, bfqq); ++ ++ /* ++ * Expire in-service queue only if preemption may be needed ++ * for guarantees. In this respect, the function ++ * next_queue_may_preempt just checks a simple, necessary ++ * condition, and not a sufficient condition based on ++ * timestamps. In fact, for the latter condition to be ++ * evaluated, timestamps would need first to be updated, and ++ * this operation is quite costly (see the comments on the ++ * function bfq_bfqq_update_budg_for_activation). ++ */ ++ if (bfqd->in_service_queue && bfqq_wants_to_preempt && ++ bfqd->in_service_queue->wr_coeff == 1 && ++ next_queue_may_preempt(bfqd)) { ++ struct bfq_queue *in_serv = ++ bfqd->in_service_queue; ++ BUG_ON(in_serv == bfqq); ++ ++ bfq_bfqq_expire(bfqd, bfqd->in_service_queue, ++ false, BFQ_BFQQ_PREEMPTED); ++ BUG_ON(in_serv->entity.budget < 0); ++ } + } + + static void bfq_add_request(struct request *rq) + { + struct bfq_queue *bfqq = RQ_BFQQ(rq); +- struct bfq_entity *entity = &bfqq->entity; + struct bfq_data *bfqd = bfqq->bfqd; + struct request *next_rq, *prev; +- unsigned long old_wr_coeff = bfqq->wr_coeff; ++ unsigned int old_wr_coeff = bfqq->wr_coeff; + bool interactive = false; + +- bfq_log_bfqq(bfqd, bfqq, "add_request %d", rq_is_sync(rq)); ++ bfq_log_bfqq(bfqd, bfqq, "add_request: size %u %s", ++ blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A"); ++ ++ if (bfqq->wr_coeff > 1) /* queue is being weight-raised */ ++ bfq_log_bfqq(bfqd, bfqq, ++ "raising period dur %u/%u msec, old coeff %u, w %d(%d)", ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqq->wr_coeff, ++ bfqq->entity.weight, bfqq->entity.orig_weight); ++ + bfqq->queued[rq_is_sync(rq)]++; + bfqd->queued++; + + elv_rb_add(&bfqq->sort_list, rq); + + /* +- * Check if this request is a better next-serve candidate. ++ * Check if this request is a better next-to-serve candidate. + */ + prev = bfqq->next_rq; + next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position); +@@ -887,160 +1373,10 @@ static void bfq_add_request(struct request *rq) + if (prev != bfqq->next_rq) + bfq_pos_tree_add_move(bfqd, bfqq); + +- if (!bfq_bfqq_busy(bfqq)) { +- bool soft_rt, coop_or_in_burst, +- idle_for_long_time = time_is_before_jiffies( +- bfqq->budget_timeout + +- bfqd->bfq_wr_min_idle_time); +- +-#ifdef CONFIG_BFQ_GROUP_IOSCHED +- bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, +- rq->cmd_flags); +-#endif +- if (bfq_bfqq_sync(bfqq)) { +- bool already_in_burst = +- !hlist_unhashed(&bfqq->burst_list_node) || +- bfq_bfqq_in_large_burst(bfqq); +- bfq_handle_burst(bfqd, bfqq, idle_for_long_time); +- /* +- * If bfqq was not already in the current burst, +- * then, at this point, bfqq either has been +- * added to the current burst or has caused the +- * current burst to terminate. In particular, in +- * the second case, bfqq has become the first +- * queue in a possible new burst. +- * In both cases last_ins_in_burst needs to be +- * moved forward. +- */ +- if (!already_in_burst) +- bfqd->last_ins_in_burst = jiffies; +- } +- +- coop_or_in_burst = bfq_bfqq_in_large_burst(bfqq) || +- bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh; +- soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && +- !coop_or_in_burst && +- time_is_before_jiffies(bfqq->soft_rt_next_start); +- interactive = !coop_or_in_burst && idle_for_long_time; +- entity->budget = max_t(unsigned long, bfqq->max_budget, +- bfq_serv_to_charge(next_rq, bfqq)); +- +- if (!bfq_bfqq_IO_bound(bfqq)) { +- if (time_before(jiffies, +- RQ_BIC(rq)->ttime.last_end_request + +- bfqd->bfq_slice_idle)) { +- bfqq->requests_within_timer++; +- if (bfqq->requests_within_timer >= +- bfqd->bfq_requests_within_timer) +- bfq_mark_bfqq_IO_bound(bfqq); +- } else +- bfqq->requests_within_timer = 0; +- } +- +- if (!bfqd->low_latency) +- goto add_bfqq_busy; +- +- if (bfq_bfqq_just_split(bfqq)) +- goto set_prio_changed; +- +- /* +- * If the queue: +- * - is not being boosted, +- * - has been idle for enough time, +- * - is not a sync queue or is linked to a bfq_io_cq (it is +- * shared "for its nature" or it is not shared and its +- * requests have not been redirected to a shared queue) +- * start a weight-raising period. +- */ +- if (old_wr_coeff == 1 && (interactive || soft_rt) && +- (!bfq_bfqq_sync(bfqq) || bfqq->bic)) { +- bfqq->wr_coeff = bfqd->bfq_wr_coeff; +- if (interactive) +- bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); +- else +- bfqq->wr_cur_max_time = +- bfqd->bfq_wr_rt_max_time; +- bfq_log_bfqq(bfqd, bfqq, +- "wrais starting at %lu, rais_max_time %u", +- jiffies, +- jiffies_to_msecs(bfqq->wr_cur_max_time)); +- } else if (old_wr_coeff > 1) { +- if (interactive) +- bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); +- else if (coop_or_in_burst || +- (bfqq->wr_cur_max_time == +- bfqd->bfq_wr_rt_max_time && +- !soft_rt)) { +- bfqq->wr_coeff = 1; +- bfq_log_bfqq(bfqd, bfqq, +- "wrais ending at %lu, rais_max_time %u", +- jiffies, +- jiffies_to_msecs(bfqq-> +- wr_cur_max_time)); +- } else if (time_before( +- bfqq->last_wr_start_finish + +- bfqq->wr_cur_max_time, +- jiffies + +- bfqd->bfq_wr_rt_max_time) && +- soft_rt) { +- /* +- * +- * The remaining weight-raising time is lower +- * than bfqd->bfq_wr_rt_max_time, which means +- * that the application is enjoying weight +- * raising either because deemed soft-rt in +- * the near past, or because deemed interactive +- * a long ago. +- * In both cases, resetting now the current +- * remaining weight-raising time for the +- * application to the weight-raising duration +- * for soft rt applications would not cause any +- * latency increase for the application (as the +- * new duration would be higher than the +- * remaining time). +- * +- * In addition, the application is now meeting +- * the requirements for being deemed soft rt. +- * In the end we can correctly and safely +- * (re)charge the weight-raising duration for +- * the application with the weight-raising +- * duration for soft rt applications. +- * +- * In particular, doing this recharge now, i.e., +- * before the weight-raising period for the +- * application finishes, reduces the probability +- * of the following negative scenario: +- * 1) the weight of a soft rt application is +- * raised at startup (as for any newly +- * created application), +- * 2) since the application is not interactive, +- * at a certain time weight-raising is +- * stopped for the application, +- * 3) at that time the application happens to +- * still have pending requests, and hence +- * is destined to not have a chance to be +- * deemed soft rt before these requests are +- * completed (see the comments to the +- * function bfq_bfqq_softrt_next_start() +- * for details on soft rt detection), +- * 4) these pending requests experience a high +- * latency because the application is not +- * weight-raised while they are pending. +- */ +- bfqq->last_wr_start_finish = jiffies; +- bfqq->wr_cur_max_time = +- bfqd->bfq_wr_rt_max_time; +- } +- } +-set_prio_changed: +- if (old_wr_coeff != bfqq->wr_coeff) +- entity->prio_changed = 1; +-add_bfqq_busy: +- bfqq->last_idle_bklogged = jiffies; +- bfqq->service_from_backlogged = 0; +- bfq_clear_bfqq_softrt_update(bfqq); +- bfq_add_bfqq_busy(bfqd, bfqq); +- } else { ++ if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */ ++ bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff, ++ rq, &interactive); ++ else { + if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) && + time_is_before_jiffies( + bfqq->last_wr_start_finish + +@@ -1049,16 +1385,43 @@ add_bfqq_busy: + bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); + + bfqd->wr_busy_queues++; +- entity->prio_changed = 1; ++ bfqq->entity.prio_changed = 1; + bfq_log_bfqq(bfqd, bfqq, +- "non-idle wrais starting at %lu, rais_max_time %u", +- jiffies, +- jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ "non-idle wrais starting, " ++ "wr_max_time %u wr_busy %d", ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqd->wr_busy_queues); + } + if (prev != bfqq->next_rq) + bfq_updated_next_req(bfqd, bfqq); + } + ++ /* ++ * Assign jiffies to last_wr_start_finish in the following ++ * cases: ++ * ++ * . if bfqq is not going to be weight-raised, because, for ++ * non weight-raised queues, last_wr_start_finish stores the ++ * arrival time of the last request; as of now, this piece ++ * of information is used only for deciding whether to ++ * weight-raise async queues ++ * ++ * . if bfqq is not weight-raised, because, if bfqq is now ++ * switching to weight-raised, then last_wr_start_finish ++ * stores the time when weight-raising starts ++ * ++ * . if bfqq is interactive, because, regardless of whether ++ * bfqq is currently weight-raised, the weight-raising ++ * period must start or restart (this case is considered ++ * separately because it is not detected by the above ++ * conditions, if bfqq is already weight-raised) ++ * ++ * last_wr_start_finish has to be updated also if bfqq is soft ++ * real-time, because the weight-raising period is constantly ++ * restarted on idle-to-busy transitions for these queues, but ++ * this is already done in bfq_bfqq_handle_idle_busy_switch if ++ * needed. ++ */ + if (bfqd->low_latency && + (old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive)) + bfqq->last_wr_start_finish = jiffies; +@@ -1106,6 +1469,9 @@ static void bfq_remove_request(struct request *rq) + struct bfq_data *bfqd = bfqq->bfqd; + const int sync = rq_is_sync(rq); + ++ BUG_ON(bfqq->entity.service > bfqq->entity.budget && ++ bfqq == bfqd->in_service_queue); ++ + if (bfqq->next_rq == rq) { + bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq); + bfq_updated_next_req(bfqd, bfqq); +@@ -1119,8 +1485,25 @@ static void bfq_remove_request(struct request *rq) + elv_rb_del(&bfqq->sort_list, rq); + + if (RB_EMPTY_ROOT(&bfqq->sort_list)) { +- if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) ++ BUG_ON(bfqq->entity.budget < 0); ++ ++ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) { + bfq_del_bfqq_busy(bfqd, bfqq, 1); ++ ++ /* bfqq emptied. In normal operation, when ++ * bfqq is empty, bfqq->entity.service and ++ * bfqq->entity.budget must contain, ++ * respectively, the service received and the ++ * budget used last time bfqq emptied. These ++ * facts do not hold in this case, as at least ++ * this last removal occurred while bfqq is ++ * not in service. To avoid inconsistencies, ++ * reset both bfqq->entity.service and ++ * bfqq->entity.budget. ++ */ ++ bfqq->entity.budget = bfqq->entity.service = 0; ++ } ++ + /* + * Remove queue from request-position tree as it is empty. + */ +@@ -1134,9 +1517,7 @@ static void bfq_remove_request(struct request *rq) + BUG_ON(bfqq->meta_pending == 0); + bfqq->meta_pending--; + } +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags); +-#endif + } + + static int bfq_merge(struct request_queue *q, struct request **req, +@@ -1221,21 +1602,25 @@ static void bfq_merged_requests(struct request_queue *q, struct request *rq, + bfqq->next_rq = rq; + + bfq_remove_request(next); +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags); +-#endif + } + + /* Must be called with bfqq != NULL */ + static void bfq_bfqq_end_wr(struct bfq_queue *bfqq) + { + BUG_ON(!bfqq); ++ + if (bfq_bfqq_busy(bfqq)) + bfqq->bfqd->wr_busy_queues--; + bfqq->wr_coeff = 1; + bfqq->wr_cur_max_time = 0; +- /* Trigger a weight change on the next activation of the queue */ ++ /* ++ * Trigger a weight change on the next invocation of ++ * __bfq_entity_update_weight_prio. ++ */ + bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "end_wr: wr_busy %d", ++ bfqq->bfqd->wr_busy_queues); + } + + static void bfq_end_wr_async_queues(struct bfq_data *bfqd, +@@ -1278,7 +1663,7 @@ static int bfq_rq_close_to_sector(void *io_struct, bool request, + sector_t sector) + { + return abs(bfq_io_struct_pos(io_struct, request) - sector) <= +- BFQQ_SEEK_THR; ++ BFQQ_CLOSE_THR; + } + + static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd, +@@ -1400,7 +1785,7 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) + * throughput. + */ + bfqq->new_bfqq = new_bfqq; +- atomic_add(process_refs, &new_bfqq->ref); ++ new_bfqq->ref += process_refs; + return new_bfqq; + } + +@@ -1431,9 +1816,23 @@ static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq, + } + + /* +- * Attempt to schedule a merge of bfqq with the currently in-service queue +- * or with a close queue among the scheduled queues. +- * Return NULL if no merge was scheduled, a pointer to the shared bfq_queue ++ * If this function returns true, then bfqq cannot be merged. The idea ++ * is that true cooperation happens very early after processes start ++ * to do I/O. Usually, late cooperations are just accidental false ++ * positives. In case bfqq is weight-raised, such false positives ++ * would evidently degrade latency guarantees for bfqq. ++ */ ++bool wr_from_too_long(struct bfq_queue *bfqq) ++{ ++ return bfqq->wr_coeff > 1 && ++ time_is_before_jiffies(bfqq->last_wr_start_finish + ++ msecs_to_jiffies(100)); ++} ++ ++/* ++ * Attempt to schedule a merge of bfqq with the currently in-service ++ * queue or with a close queue among the scheduled queues. Return ++ * NULL if no merge was scheduled, a pointer to the shared bfq_queue + * structure otherwise. + * + * The OOM queue is not allowed to participate to cooperation: in fact, since +@@ -1442,6 +1841,18 @@ static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq, + * handle merging with the OOM queue would be quite complex and expensive + * to maintain. Besides, in such a critical condition as an out of memory, + * the benefits of queue merging may be little relevant, or even negligible. ++ * ++ * Weight-raised queues can be merged only if their weight-raising ++ * period has just started. In fact cooperating processes are usually ++ * started together. Thus, with this filter we avoid false positives ++ * that would jeopardize low-latency guarantees. ++ * ++ * WARNING: queue merging may impair fairness among non-weight raised ++ * queues, for at least two reasons: 1) the original weight of a ++ * merged queue may change during the merged state, 2) even being the ++ * weight the same, a merged queue may be bloated with many more ++ * requests than the ones produced by its originally-associated ++ * process. + */ + static struct bfq_queue * + bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, +@@ -1451,16 +1862,32 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, + + if (bfqq->new_bfqq) + return bfqq->new_bfqq; +- if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) ++ ++ if (io_struct && wr_from_too_long(bfqq) && ++ likely(bfqq != &bfqd->oom_bfqq)) ++ bfq_log_bfqq(bfqd, bfqq, ++ "would have looked for coop, but bfq%d wr", ++ bfqq->pid); ++ ++ if (!io_struct || ++ wr_from_too_long(bfqq) || ++ unlikely(bfqq == &bfqd->oom_bfqq)) + return NULL; +- /* If device has only one backlogged bfq_queue, don't search. */ ++ ++ /* If there is only one backlogged queue, don't search. */ + if (bfqd->busy_queues == 1) + return NULL; + + in_service_bfqq = bfqd->in_service_queue; + ++ if (in_service_bfqq && in_service_bfqq != bfqq && ++ bfqd->in_service_bic && wr_from_too_long(in_service_bfqq) ++ && likely(in_service_bfqq == &bfqd->oom_bfqq)) ++ bfq_log_bfqq(bfqd, bfqq, ++ "would have tried merge with in-service-queue, but wr"); ++ + if (!in_service_bfqq || in_service_bfqq == bfqq || +- !bfqd->in_service_bic || ++ !bfqd->in_service_bic || wr_from_too_long(in_service_bfqq) || + unlikely(in_service_bfqq == &bfqd->oom_bfqq)) + goto check_scheduled; + +@@ -1482,7 +1909,15 @@ check_scheduled: + + BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent); + +- if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) && ++ if (new_bfqq && wr_from_too_long(new_bfqq) && ++ likely(new_bfqq != &bfqd->oom_bfqq) && ++ bfq_may_be_close_cooperator(bfqq, new_bfqq)) ++ bfq_log_bfqq(bfqd, bfqq, ++ "would have merged with bfq%d, but wr", ++ new_bfqq->pid); ++ ++ if (new_bfqq && !wr_from_too_long(new_bfqq) && ++ likely(new_bfqq != &bfqd->oom_bfqq) && + bfq_may_be_close_cooperator(bfqq, new_bfqq)) + return bfq_setup_merge(bfqq, new_bfqq); + +@@ -1498,46 +1933,11 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq) + */ + if (!bfqq->bic) + return; +- if (bfqq->bic->wr_time_left) +- /* +- * This is the queue of a just-started process, and would +- * deserve weight raising: we set wr_time_left to the full +- * weight-raising duration to trigger weight-raising when +- * and if the queue is split and the first request of the +- * queue is enqueued. +- */ +- bfqq->bic->wr_time_left = bfq_wr_duration(bfqq->bfqd); +- else if (bfqq->wr_coeff > 1) { +- unsigned long wr_duration = +- jiffies - bfqq->last_wr_start_finish; +- /* +- * It may happen that a queue's weight raising period lasts +- * longer than its wr_cur_max_time, as weight raising is +- * handled only when a request is enqueued or dispatched (it +- * does not use any timer). If the weight raising period is +- * about to end, don't save it. +- */ +- if (bfqq->wr_cur_max_time <= wr_duration) +- bfqq->bic->wr_time_left = 0; +- else +- bfqq->bic->wr_time_left = +- bfqq->wr_cur_max_time - wr_duration; +- /* +- * The bfq_queue is becoming shared or the requests of the +- * process owning the queue are being redirected to a shared +- * queue. Stop the weight raising period of the queue, as in +- * both cases it should not be owned by an interactive or +- * soft real-time application. +- */ +- bfq_bfqq_end_wr(bfqq); +- } else +- bfqq->bic->wr_time_left = 0; ++ + bfqq->bic->saved_idle_window = bfq_bfqq_idle_window(bfqq); + bfqq->bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq); + bfqq->bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq); + bfqq->bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node); +- bfqq->bic->cooperations++; +- bfqq->bic->failed_cooperations = 0; + } + + static void bfq_get_bic_reference(struct bfq_queue *bfqq) +@@ -1562,6 +1962,40 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, + if (bfq_bfqq_IO_bound(bfqq)) + bfq_mark_bfqq_IO_bound(new_bfqq); + bfq_clear_bfqq_IO_bound(bfqq); ++ ++ /* ++ * If bfqq is weight-raised, then let new_bfqq inherit ++ * weight-raising. To reduce false positives, neglect the case ++ * where bfqq has just been created, but has not yet made it ++ * to be weight-raised (which may happen because EQM may merge ++ * bfqq even before bfq_add_request is executed for the first ++ * time for bfqq). Handling this case would however be very ++ * easy, thanks to the flag just_created. ++ */ ++ if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) { ++ new_bfqq->wr_coeff = bfqq->wr_coeff; ++ new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time; ++ new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish; ++ if (bfq_bfqq_busy(new_bfqq)) ++ bfqd->wr_busy_queues++; ++ new_bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqd, new_bfqq, ++ "wr starting after merge with %d, " ++ "rais_max_time %u", ++ bfqq->pid, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */ ++ bfqq->wr_coeff = 1; ++ bfqq->entity.prio_changed = 1; ++ if (bfq_bfqq_busy(bfqq)) ++ bfqd->wr_busy_queues--; ++ } ++ ++ bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d", ++ bfqd->wr_busy_queues); ++ + /* + * Grab a reference to the bic, to prevent it from being destroyed + * before being possibly touched by a bfq_split_bfqq(). +@@ -1588,18 +2022,6 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, + bfq_put_queue(bfqq); + } + +-static void bfq_bfqq_increase_failed_cooperations(struct bfq_queue *bfqq) +-{ +- struct bfq_io_cq *bic = bfqq->bic; +- struct bfq_data *bfqd = bfqq->bfqd; +- +- if (bic && bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh) { +- bic->failed_cooperations++; +- if (bic->failed_cooperations >= bfqd->bfq_failed_cooperations) +- bic->cooperations = 0; +- } +-} +- + static int bfq_allow_merge(struct request_queue *q, struct request *rq, + struct bio *bio) + { +@@ -1637,30 +2059,86 @@ static int bfq_allow_merge(struct request_queue *q, struct request *rq, + * to decide whether bio and rq can be merged. + */ + bfqq = new_bfqq; +- } else +- bfq_bfqq_increase_failed_cooperations(bfqq); ++ } + } + + return bfqq == RQ_BFQQ(rq); + } + ++/* ++ * Set the maximum time for the in-service queue to consume its ++ * budget. This prevents seeky processes from lowering the throughput. ++ * In practice, a time-slice service scheme is used with seeky ++ * processes. ++ */ ++static void bfq_set_budget_timeout(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ unsigned int timeout_coeff; ++ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time) ++ timeout_coeff = 1; ++ else ++ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight; ++ ++ bfqd->last_budget_start = ktime_get(); ++ ++ bfqq->budget_timeout = jiffies + ++ bfqd->bfq_timeout * timeout_coeff; ++ ++ bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u", ++ jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff)); ++} ++ + static void __bfq_set_in_service_queue(struct bfq_data *bfqd, + struct bfq_queue *bfqq) + { + if (bfqq) { +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_avg_queue_size(bfqq_group(bfqq)); +-#endif + bfq_mark_bfqq_must_alloc(bfqq); +- bfq_mark_bfqq_budget_new(bfqq); + bfq_clear_bfqq_fifo_expire(bfqq); + + bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8; + ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ if (bfqq->wr_coeff > 1 && ++ bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && ++ time_is_before_jiffies(bfqq->budget_timeout)) { ++ /* ++ * For soft real-time queues, move the start ++ * of the weight-raising period forward by the ++ * time the queue has not received any ++ * service. Otherwise, a relatively long ++ * service delay is likely to cause the ++ * weight-raising period of the queue to end, ++ * because of the short duration of the ++ * weight-raising period of a soft real-time ++ * queue. It is worth noting that this move ++ * is not so dangerous for the other queues, ++ * because soft real-time queues are not ++ * greedy. ++ * ++ * To not add a further variable, we use the ++ * overloaded field budget_timeout to ++ * determine for how long the queue has not ++ * received service, i.e., how much time has ++ * elapsed since the queue expired. However, ++ * this is a little imprecise, because ++ * budget_timeout is set to jiffies if bfqq ++ * not only expires, but also remains with no ++ * request. ++ */ ++ bfqq->last_wr_start_finish += jiffies - ++ bfqq->budget_timeout; ++ } ++ ++ bfq_set_budget_timeout(bfqd, bfqq); + bfq_log_bfqq(bfqd, bfqq, + "set_in_service_queue, cur-budget = %d", + bfqq->entity.budget); +- } ++ } else ++ bfq_log(bfqd, "set_in_service_queue: NULL"); + + bfqd->in_service_queue = bfqq; + } +@@ -1676,31 +2154,6 @@ static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd) + return bfqq; + } + +-/* +- * If enough samples have been computed, return the current max budget +- * stored in bfqd, which is dynamically updated according to the +- * estimated disk peak rate; otherwise return the default max budget +- */ +-static int bfq_max_budget(struct bfq_data *bfqd) +-{ +- if (bfqd->budgets_assigned < bfq_stats_min_budgets) +- return bfq_default_max_budget; +- else +- return bfqd->bfq_max_budget; +-} +- +-/* +- * Return min budget, which is a fraction of the current or default +- * max budget (trying with 1/32) +- */ +-static int bfq_min_budget(struct bfq_data *bfqd) +-{ +- if (bfqd->budgets_assigned < bfq_stats_min_budgets) +- return bfq_default_max_budget / 32; +- else +- return bfqd->bfq_max_budget / 32; +-} +- + static void bfq_arm_slice_timer(struct bfq_data *bfqd) + { + struct bfq_queue *bfqq = bfqd->in_service_queue; +@@ -1723,64 +2176,36 @@ static void bfq_arm_slice_timer(struct bfq_data *bfqd) + * + * To prevent processes with (partly) seeky workloads from + * being too ill-treated, grant them a small fraction of the +- * assigned budget before reducing the waiting time to +- * BFQ_MIN_TT. This happened to help reduce latency. +- */ +- sl = bfqd->bfq_slice_idle; +- /* +- * Unless the queue is being weight-raised or the scenario is +- * asymmetric, grant only minimum idle time if the queue either +- * has been seeky for long enough or has already proved to be +- * constantly seeky. +- */ +- if (bfq_sample_valid(bfqq->seek_samples) && +- ((BFQQ_SEEKY(bfqq) && bfqq->entity.service > +- bfq_max_budget(bfqq->bfqd) / 8) || +- bfq_bfqq_constantly_seeky(bfqq)) && bfqq->wr_coeff == 1 && +- bfq_symmetric_scenario(bfqd)) +- sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT)); +- else if (bfqq->wr_coeff > 1) +- sl = sl * 3; +- bfqd->last_idling_start = ktime_get(); +- mod_timer(&bfqd->idle_slice_timer, jiffies + sl); +-#ifdef CONFIG_BFQ_GROUP_IOSCHED +- bfqg_stats_set_start_idle_time(bfqq_group(bfqq)); +-#endif +- bfq_log(bfqd, "arm idle: %u/%u ms", +- jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle)); +-} +- +-/* +- * Set the maximum time for the in-service queue to consume its +- * budget. This prevents seeky processes from lowering the disk +- * throughput (always guaranteed with a time slice scheme as in CFQ). +- */ +-static void bfq_set_budget_timeout(struct bfq_data *bfqd) +-{ +- struct bfq_queue *bfqq = bfqd->in_service_queue; +- unsigned int timeout_coeff; +- if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time) +- timeout_coeff = 1; +- else +- timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight; +- +- bfqd->last_budget_start = ktime_get(); +- +- bfq_clear_bfqq_budget_new(bfqq); +- bfqq->budget_timeout = jiffies + +- bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * timeout_coeff; ++ * assigned budget before reducing the waiting time to ++ * BFQ_MIN_TT. This happened to help reduce latency. ++ */ ++ sl = bfqd->bfq_slice_idle; ++ /* ++ * Unless the queue is being weight-raised or the scenario is ++ * asymmetric, grant only minimum idle time if the queue ++ * is seeky. A long idling is preserved for a weight-raised ++ * queue, or, more in general, in an asymemtric scenario, ++ * because a long idling is needed for guaranteeing to a queue ++ * its reserved share of the throughput (in particular, it is ++ * needed if the queue has a higher weight than some other ++ * queue). ++ */ ++ if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 && ++ bfq_symmetric_scenario(bfqd)) ++ sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT)); + +- bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u", +- jiffies_to_msecs(bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * +- timeout_coeff)); ++ bfqd->last_idling_start = ktime_get(); ++ mod_timer(&bfqd->idle_slice_timer, jiffies + sl); ++ bfqg_stats_set_start_idle_time(bfqq_group(bfqq)); ++ bfq_log(bfqd, "arm idle: %u/%u ms", ++ jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle)); + } + + /* +- * Move request from internal lists to the request queue dispatch list. ++ * Move request from internal lists to the dispatch list of the request queue + */ + static void bfq_dispatch_insert(struct request_queue *q, struct request *rq) + { +- struct bfq_data *bfqd = q->elevator->elevator_data; + struct bfq_queue *bfqq = RQ_BFQQ(rq); + + /* +@@ -1794,15 +2219,9 @@ static void bfq_dispatch_insert(struct request_queue *q, struct request *rq) + * incrementing bfqq->dispatched. + */ + bfqq->dispatched++; ++ + bfq_remove_request(rq); + elv_dispatch_sort(q, rq); +- +- if (bfq_bfqq_sync(bfqq)) +- bfqd->sync_flight++; +-#ifdef CONFIG_BFQ_GROUP_IOSCHED +- bfqg_stats_update_dispatch(bfqq_group(bfqq), blk_rq_bytes(rq), +- rq->cmd_flags); +-#endif + } + + /* +@@ -1822,18 +2241,12 @@ static struct request *bfq_check_fifo(struct bfq_queue *bfqq) + + rq = rq_entry_fifo(bfqq->fifo.next); + +- if (time_before(jiffies, rq->fifo_time)) ++ if (time_is_after_jiffies(rq->fifo_time)) + return NULL; + + return rq; + } + +-static int bfq_bfqq_budget_left(struct bfq_queue *bfqq) +-{ +- struct bfq_entity *entity = &bfqq->entity; +- return entity->budget - entity->service; +-} +- + static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) + { + BUG_ON(bfqq != bfqd->in_service_queue); +@@ -1850,12 +2263,15 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) + bfq_mark_bfqq_split_coop(bfqq); + + if (RB_EMPTY_ROOT(&bfqq->sort_list)) { +- /* +- * Overloading budget_timeout field to store the time +- * at which the queue remains with no backlog; used by +- * the weight-raising mechanism. +- */ +- bfqq->budget_timeout = jiffies; ++ if (bfqq->dispatched == 0) ++ /* ++ * Overloading budget_timeout field to store ++ * the time at which the queue remains with no ++ * backlog and no outstanding request; used by ++ * the weight-raising mechanism. ++ */ ++ bfqq->budget_timeout = jiffies; ++ + bfq_del_bfqq_busy(bfqd, bfqq, 1); + } else { + bfq_activate_bfqq(bfqd, bfqq); +@@ -1882,10 +2298,19 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, + struct request *next_rq; + int budget, min_budget; + +- budget = bfqq->max_budget; ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ + min_budget = bfq_min_budget(bfqd); + +- BUG_ON(bfqq != bfqd->in_service_queue); ++ if (bfqq->wr_coeff == 1) ++ budget = bfqq->max_budget; ++ else /* ++ * Use a constant, low budget for weight-raised queues, ++ * to help achieve a low latency. Keep it slightly higher ++ * than the minimum possible budget, to cause a little ++ * bit fewer expirations. ++ */ ++ budget = 2 * min_budget; + + bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d", + bfqq->entity.budget, bfq_bfqq_budget_left(bfqq)); +@@ -1894,7 +2319,7 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, + bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d", + bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue)); + +- if (bfq_bfqq_sync(bfqq)) { ++ if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) { + switch (reason) { + /* + * Caveat: in all the following cases we trade latency +@@ -1936,14 +2361,10 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, + break; + case BFQ_BFQQ_BUDGET_TIMEOUT: + /* +- * We double the budget here because: 1) it +- * gives the chance to boost the throughput if +- * this is not a seeky process (which may have +- * bumped into this timeout because of, e.g., +- * ZBR), 2) together with charge_full_budget +- * it helps give seeky processes higher +- * timestamps, and hence be served less +- * frequently. ++ * We double the budget here because it gives ++ * the chance to boost the throughput if this ++ * is not a seeky process (and has bumped into ++ * this timeout because of, e.g., ZBR). + */ + budget = min(budget * 2, bfqd->bfq_max_budget); + break; +@@ -1960,17 +2381,49 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, + budget = min(budget * 4, bfqd->bfq_max_budget); + break; + case BFQ_BFQQ_NO_MORE_REQUESTS: +- /* +- * Leave the budget unchanged. +- */ ++ /* ++ * For queues that expire for this reason, it ++ * is particularly important to keep the ++ * budget close to the actual service they ++ * need. Doing so reduces the timestamp ++ * misalignment problem described in the ++ * comments in the body of ++ * __bfq_activate_entity. In fact, suppose ++ * that a queue systematically expires for ++ * BFQ_BFQQ_NO_MORE_REQUESTS and presents a ++ * new request in time to enjoy timestamp ++ * back-shifting. The larger the budget of the ++ * queue is with respect to the service the ++ * queue actually requests in each service ++ * slot, the more times the queue can be ++ * reactivated with the same virtual finish ++ * time. It follows that, even if this finish ++ * time is pushed to the system virtual time ++ * to reduce the consequent timestamp ++ * misalignment, the queue unjustly enjoys for ++ * many re-activations a lower finish time ++ * than all newly activated queues. ++ * ++ * The service needed by bfqq is measured ++ * quite precisely by bfqq->entity.service. ++ * Since bfqq does not enjoy device idling, ++ * bfqq->entity.service is equal to the number ++ * of sectors that the process associated with ++ * bfqq requested to read/write before waiting ++ * for request completions, or blocking for ++ * other reasons. ++ */ ++ budget = max_t(int, bfqq->entity.service, min_budget); ++ break; + default: + return; + } +- } else ++ } else if (!bfq_bfqq_sync(bfqq)) + /* +- * Async queues get always the maximum possible budget +- * (their ability to dispatch is limited by +- * @bfqd->bfq_max_budget_async_rq). ++ * Async queues get always the maximum possible ++ * budget, as for them we do not care about latency ++ * (in addition, their ability to dispatch is limited ++ * by the charging factor). + */ + budget = bfqd->bfq_max_budget; + +@@ -1981,65 +2434,105 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, + bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget); + + /* +- * Make sure that we have enough budget for the next request. +- * Since the finish time of the bfqq must be kept in sync with +- * the budget, be sure to call __bfq_bfqq_expire() after the ++ * If there is still backlog, then assign a new budget, making ++ * sure that it is large enough for the next request. Since ++ * the finish time of bfqq must be kept in sync with the ++ * budget, be sure to call __bfq_bfqq_expire() *after* this + * update. ++ * ++ * If there is no backlog, then no need to update the budget; ++ * it will be updated on the arrival of a new request. + */ + next_rq = bfqq->next_rq; +- if (next_rq) ++ if (next_rq) { ++ BUG_ON(reason == BFQ_BFQQ_TOO_IDLE || ++ reason == BFQ_BFQQ_NO_MORE_REQUESTS); + bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget, + bfq_serv_to_charge(next_rq, bfqq)); +- else +- bfqq->entity.budget = bfqq->max_budget; ++ BUG_ON(!bfq_bfqq_busy(bfqq)); ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ } + + bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d", + next_rq ? blk_rq_sectors(next_rq) : 0, + bfqq->entity.budget); + } + +-static unsigned long bfq_calc_max_budget(u64 peak_rate, u64 timeout) ++static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd) + { +- unsigned long max_budget; +- + /* + * The max_budget calculated when autotuning is equal to the +- * amount of sectors transfered in timeout_sync at the ++ * amount of sectors transfered in timeout at the + * estimated peak rate. + */ +- max_budget = (unsigned long)(peak_rate * 1000 * +- timeout >> BFQ_RATE_SHIFT); +- +- return max_budget; ++ return bfqd->peak_rate * 1000 * jiffies_to_msecs(bfqd->bfq_timeout) >> ++ BFQ_RATE_SHIFT; + } + + /* +- * In addition to updating the peak rate, checks whether the process +- * is "slow", and returns 1 if so. This slow flag is used, in addition +- * to the budget timeout, to reduce the amount of service provided to +- * seeky processes, and hence reduce their chances to lower the +- * throughput. See the code for more details. ++ * Update the read peak rate (quantity used for auto-tuning) as a ++ * function of the rate at which bfqq has been served, and check ++ * whether the process associated with bfqq is "slow". Return true if ++ * the process is slow. The slow flag is used, in addition to the ++ * budget timeout, to reduce the amount of service provided to seeky ++ * processes, and hence reduce their chances to lower the ++ * throughput. More details in the body of the function. ++ * ++ * An important observation is in order: with devices with internal ++ * queues, it is hard if ever possible to know when and for how long ++ * an I/O request is processed by the device (apart from the trivial ++ * I/O pattern where a new request is dispatched only after the ++ * previous one has been completed). This makes it hard to evaluate ++ * the real rate at which the I/O requests of each bfq_queue are ++ * served. In fact, for an I/O scheduler like BFQ, serving a ++ * bfq_queue means just dispatching its requests during its service ++ * slot, i.e., until the budget of the queue is exhausted, or the ++ * queue remains idle, or, finally, a timeout fires. But, during the ++ * service slot of a bfq_queue, the device may be still processing ++ * requests of bfq_queues served in previous service slots. On the ++ * opposite end, the requests of the in-service bfq_queue may be ++ * completed after the service slot of the queue finishes. Anyway, ++ * unless more sophisticated solutions are used (where possible), the ++ * sum of the sizes of the requests dispatched during the service slot ++ * of a bfq_queue is probably the only approximation available for ++ * the service received by the bfq_queue during its service slot. And, ++ * as written above, this sum is the quantity used in this function to ++ * evaluate the peak rate. + */ + static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, +- bool compensate, enum bfqq_expiration reason) ++ bool compensate, enum bfqq_expiration reason, ++ unsigned long *delta_ms) + { +- u64 bw, usecs, expected, timeout; +- ktime_t delta; ++ u64 bw, bwdiv10, delta_usecs, delta_ms_tmp; ++ ktime_t delta_ktime; + int update = 0; ++ bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */ + +- if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq)) ++ if (!bfq_bfqq_sync(bfqq)) + return false; + + if (compensate) +- delta = bfqd->last_idling_start; ++ delta_ktime = bfqd->last_idling_start; + else +- delta = ktime_get(); +- delta = ktime_sub(delta, bfqd->last_budget_start); +- usecs = ktime_to_us(delta); ++ delta_ktime = ktime_get(); ++ delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start); ++ delta_usecs = ktime_to_us(delta_ktime); + + /* Don't trust short/unrealistic values. */ +- if (usecs < 100 || usecs >= LONG_MAX) +- return false; ++ if (delta_usecs < 1000 || delta_usecs >= LONG_MAX) { ++ if (blk_queue_nonrot(bfqd->queue)) ++ *delta_ms = BFQ_MIN_TT; /* give same worst-case ++ guarantees as ++ idling for seeky ++ */ ++ else /* Charge at least one seek */ ++ *delta_ms = jiffies_to_msecs(bfq_slice_idle); ++ return slow; ++ } ++ ++ delta_ms_tmp = delta_usecs; ++ do_div(delta_ms_tmp, 1000); ++ *delta_ms = delta_ms_tmp; + + /* + * Calculate the bandwidth for the last slice. We use a 64 bit +@@ -2048,32 +2541,51 @@ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, + * and to avoid overflows. + */ + bw = (u64)bfqq->entity.service << BFQ_RATE_SHIFT; +- do_div(bw, (unsigned long)usecs); +- +- timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]); ++ do_div(bw, (unsigned long)delta_usecs); + ++ bfq_log(bfqd, "measured bw = %llu sects/sec", ++ (1000000*bw)>>BFQ_RATE_SHIFT); + /* + * Use only long (> 20ms) intervals to filter out spikes for + * the peak rate estimation. + */ +- if (usecs > 20000) { ++ if (delta_usecs > 20000) { ++ bool fully_sequential = bfqq->seek_history == 0; ++ /* ++ * Soft real-time queues are not good candidates for ++ * evaluating bw, as they are likely to be slow even ++ * if sequential. ++ */ ++ bool non_soft_rt = bfqq->wr_coeff == 1 || ++ bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time; ++ bool consumed_large_budget = ++ reason == BFQ_BFQQ_BUDGET_EXHAUSTED && ++ bfqq->entity.budget >= bfqd->bfq_max_budget * 2 / 3; ++ bool served_for_long_time = ++ reason == BFQ_BFQQ_BUDGET_TIMEOUT || ++ consumed_large_budget; ++ ++ BUG_ON(bfqq->seek_history == 0 && ++ hweight32(bfqq->seek_history) != 0); ++ + if (bw > bfqd->peak_rate || +- (!BFQQ_SEEKY(bfqq) && +- reason == BFQ_BFQQ_BUDGET_TIMEOUT)) { +- bfq_log(bfqd, "measured bw =%llu", bw); ++ (bfq_bfqq_sync(bfqq) && fully_sequential && non_soft_rt && ++ served_for_long_time)) { + /* + * To smooth oscillations use a low-pass filter with +- * alpha=7/8, i.e., +- * new_rate = (7/8) * old_rate + (1/8) * bw ++ * alpha=9/10, i.e., ++ * new_rate = (9/10) * old_rate + (1/10) * bw + */ +- do_div(bw, 8); +- if (bw == 0) +- return 0; +- bfqd->peak_rate *= 7; +- do_div(bfqd->peak_rate, 8); +- bfqd->peak_rate += bw; ++ bwdiv10 = bw; ++ do_div(bwdiv10, 10); ++ if (bwdiv10 == 0) ++ return false; /* bw too low to be used */ ++ bfqd->peak_rate *= 9; ++ do_div(bfqd->peak_rate, 10); ++ bfqd->peak_rate += bwdiv10; + update = 1; +- bfq_log(bfqd, "new peak_rate=%llu", bfqd->peak_rate); ++ bfq_log(bfqd, "new peak_rate = %llu sects/sec", ++ (1000000*bfqd->peak_rate)>>BFQ_RATE_SHIFT); + } + + update |= bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES - 1; +@@ -2086,9 +2598,8 @@ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, + int dev_type = blk_queue_nonrot(bfqd->queue); + if (bfqd->bfq_user_max_budget == 0) { + bfqd->bfq_max_budget = +- bfq_calc_max_budget(bfqd->peak_rate, +- timeout); +- bfq_log(bfqd, "new max_budget=%d", ++ bfq_calc_max_budget(bfqd); ++ bfq_log(bfqd, "new max_budget = %d", + bfqd->bfq_max_budget); + } + if (bfqd->device_speed == BFQ_BFQD_FAST && +@@ -2102,38 +2613,35 @@ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bfqd->RT_prod = R_fast[dev_type] * + T_fast[dev_type]; + } ++ bfq_log(bfqd, "dev_speed_class = %d (%d sects/sec), " ++ "thresh %d setcs/sec", ++ bfqd->device_speed, ++ bfqd->device_speed == BFQ_BFQD_FAST ? ++ (1000000*R_fast[dev_type])>>BFQ_RATE_SHIFT : ++ (1000000*R_slow[dev_type])>>BFQ_RATE_SHIFT, ++ (1000000*device_speed_thresh[dev_type])>> ++ BFQ_RATE_SHIFT); + } ++ /* ++ * Caveat: processes doing IO in the slower disk zones ++ * tend to be slow(er) even if not seeky. In this ++ * respect, the estimated peak rate is likely to be an ++ * average over the disk surface. Accordingly, to not ++ * be too harsh with unlucky processes, a process is ++ * deemed slow only if its bw has been lower than half ++ * of the estimated peak rate. ++ */ ++ slow = bw < bfqd->peak_rate / 2; + } + +- /* +- * If the process has been served for a too short time +- * interval to let its possible sequential accesses prevail on +- * the initial seek time needed to move the disk head on the +- * first sector it requested, then give the process a chance +- * and for the moment return false. +- */ +- if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8) +- return false; +- +- /* +- * A process is considered ``slow'' (i.e., seeky, so that we +- * cannot treat it fairly in the service domain, as it would +- * slow down too much the other processes) if, when a slice +- * ends for whatever reason, it has received service at a +- * rate that would not be high enough to complete the budget +- * before the budget timeout expiration. +- */ +- expected = bw * 1000 * timeout >> BFQ_RATE_SHIFT; ++ bfq_log_bfqq(bfqd, bfqq, ++ "update_peak_rate: bw %llu sect/s, peak rate %llu, " ++ "slow %d", ++ (1000000*bw)>>BFQ_RATE_SHIFT, ++ (1000000*bfqd->peak_rate)>>BFQ_RATE_SHIFT, ++ bw < bfqd->peak_rate / 2); + +- /* +- * Caveat: processes doing IO in the slower disk zones will +- * tend to be slow(er) even if not seeky. And the estimated +- * peak rate will actually be an average over the disk +- * surface. Hence, to not be too harsh with unlucky processes, +- * we keep a budget/3 margin of safety before declaring a +- * process slow. +- */ +- return expected > (4 * bfqq->entity.budget) / 3; ++ return slow; + } + + /* +@@ -2191,6 +2699,15 @@ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, + static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, + struct bfq_queue *bfqq) + { ++ bfq_log_bfqq(bfqd, bfqq, ++ "softrt_next_start: service_blkg %lu " ++ "soft_rate %u sects/sec" ++ "interval %u", ++ bfqq->service_from_backlogged, ++ bfqd->bfq_wr_max_softrt_rate, ++ jiffies_to_msecs(HZ * bfqq->service_from_backlogged / ++ bfqd->bfq_wr_max_softrt_rate)); ++ + return max(bfqq->last_idle_bklogged + + HZ * bfqq->service_from_backlogged / + bfqd->bfq_wr_max_softrt_rate, +@@ -2198,13 +2715,21 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, + } + + /* +- * Return the largest-possible time instant such that, for as long as possible, +- * the current time will be lower than this time instant according to the macro +- * time_is_before_jiffies(). ++ * Return the farthest future time instant according to jiffies ++ * macros. ++ */ ++static unsigned long bfq_greatest_from_now(void) ++{ ++ return jiffies + MAX_JIFFY_OFFSET; ++} ++ ++/* ++ * Return the farthest past time instant according to jiffies ++ * macros. + */ +-static unsigned long bfq_infinity_from_now(unsigned long now) ++static unsigned long bfq_smallest_from_now(void) + { +- return now + ULONG_MAX / 2; ++ return jiffies - MAX_JIFFY_OFFSET; + } + + /** +@@ -2214,28 +2739,24 @@ static unsigned long bfq_infinity_from_now(unsigned long now) + * @compensate: if true, compensate for the time spent idling. + * @reason: the reason causing the expiration. + * ++ * If the process associated with bfqq does slow I/O (e.g., because it ++ * issues random requests), we charge bfqq with the time it has been ++ * in service instead of the service it has received (see ++ * bfq_bfqq_charge_time for details on how this goal is achieved). As ++ * a consequence, bfqq will typically get higher timestamps upon ++ * reactivation, and hence it will be rescheduled as if it had ++ * received more service than what it has actually received. In the ++ * end, bfqq receives less service in proportion to how slowly its ++ * associated process consumes its budgets (and hence how seriously it ++ * tends to lower the throughput). In addition, this time-charging ++ * strategy guarantees time fairness among slow processes. In ++ * contrast, if the process associated with bfqq is not slow, we ++ * charge bfqq exactly with the service it has received. + * +- * If the process associated to the queue is slow (i.e., seeky), or in +- * case of budget timeout, or, finally, if it is async, we +- * artificially charge it an entire budget (independently of the +- * actual service it received). As a consequence, the queue will get +- * higher timestamps than the correct ones upon reactivation, and +- * hence it will be rescheduled as if it had received more service +- * than what it actually received. In the end, this class of processes +- * will receive less service in proportion to how slowly they consume +- * their budgets (and hence how seriously they tend to lower the +- * throughput). +- * +- * In contrast, when a queue expires because it has been idling for +- * too much or because it exhausted its budget, we do not touch the +- * amount of service it has received. Hence when the queue will be +- * reactivated and its timestamps updated, the latter will be in sync +- * with the actual service received by the queue until expiration. +- * +- * Charging a full budget to the first type of queues and the exact +- * service to the others has the effect of using the WF2Q+ policy to +- * schedule the former on a timeslice basis, without violating the +- * service domain guarantees of the latter. ++ * Charging time to the first type of queues and the exact service to ++ * the other has the effect of using the WF2Q+ policy to schedule the ++ * former on a timeslice basis, without violating service domain ++ * guarantees among the latter. + */ + static void bfq_bfqq_expire(struct bfq_data *bfqd, + struct bfq_queue *bfqq, +@@ -2243,40 +2764,51 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd, + enum bfqq_expiration reason) + { + bool slow; ++ unsigned long delta = 0; ++ struct bfq_entity *entity = &bfqq->entity; ++ + BUG_ON(bfqq != bfqd->in_service_queue); + + /* +- * Update disk peak rate for autotuning and check whether the ++ * Update device peak rate for autotuning and check whether the + * process is slow (see bfq_update_peak_rate). + */ +- slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason); ++ slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason, &delta); + + /* +- * As above explained, 'punish' slow (i.e., seeky), timed-out +- * and async queues, to favor sequential sync workloads. +- * +- * Processes doing I/O in the slower disk zones will tend to be +- * slow(er) even if not seeky. Hence, since the estimated peak +- * rate is actually an average over the disk surface, these +- * processes may timeout just for bad luck. To avoid punishing +- * them we do not charge a full budget to a process that +- * succeeded in consuming at least 2/3 of its budget. ++ * Increase service_from_backlogged before next statement, ++ * because the possible next invocation of ++ * bfq_bfqq_charge_time would likely inflate ++ * entity->service. In contrast, service_from_backlogged must ++ * contain real service, to enable the soft real-time ++ * heuristic to correctly compute the bandwidth consumed by ++ * bfqq. + */ +- if (slow || (reason == BFQ_BFQQ_BUDGET_TIMEOUT && +- bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3)) +- bfq_bfqq_charge_full_budget(bfqq); ++ bfqq->service_from_backlogged += entity->service; + +- bfqq->service_from_backlogged += bfqq->entity.service; +- +- if (BFQQ_SEEKY(bfqq) && reason == BFQ_BFQQ_BUDGET_TIMEOUT && +- !bfq_bfqq_constantly_seeky(bfqq)) { +- bfq_mark_bfqq_constantly_seeky(bfqq); +- if (!blk_queue_nonrot(bfqd->queue)) +- bfqd->const_seeky_busy_in_flight_queues++; +- } ++ /* ++ * As above explained, charge slow (typically seeky) and ++ * timed-out queues with the time and not the service ++ * received, to favor sequential workloads. ++ * ++ * Processes doing I/O in the slower disk zones will tend to ++ * be slow(er) even if not seeky. Therefore, since the ++ * estimated peak rate is actually an average over the disk ++ * surface, these processes may timeout just for bad luck. To ++ * avoid punishing them, do not charge time to processes that ++ * succeeded in consuming at least 2/3 of their budget. This ++ * allows BFQ to preserve enough elasticity to still perform ++ * bandwidth, and not time, distribution with little unlucky ++ * or quasi-sequential processes. ++ */ ++ if (bfqq->wr_coeff == 1 && ++ (slow || ++ (reason == BFQ_BFQQ_BUDGET_TIMEOUT && ++ bfq_bfqq_budget_left(bfqq) >= entity->budget / 3))) ++ bfq_bfqq_charge_time(bfqd, bfqq, delta); + + if (reason == BFQ_BFQQ_TOO_IDLE && +- bfqq->entity.service <= 2 * bfqq->entity.budget / 10 ) ++ entity->service <= 2 * entity->budget / 10 ) + bfq_clear_bfqq_IO_bound(bfqq); + + if (bfqd->low_latency && bfqq->wr_coeff == 1) +@@ -2285,19 +2817,23 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd, + if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 && + RB_EMPTY_ROOT(&bfqq->sort_list)) { + /* +- * If we get here, and there are no outstanding requests, +- * then the request pattern is isochronous (see the comments +- * to the function bfq_bfqq_softrt_next_start()). Hence we +- * can compute soft_rt_next_start. If, instead, the queue +- * still has outstanding requests, then we have to wait +- * for the completion of all the outstanding requests to ++ * If we get here, and there are no outstanding ++ * requests, then the request pattern is isochronous ++ * (see the comments on the function ++ * bfq_bfqq_softrt_next_start()). Thus we can compute ++ * soft_rt_next_start. If, instead, the queue still ++ * has outstanding requests, then we have to wait for ++ * the completion of all the outstanding requests to + * discover whether the request pattern is actually + * isochronous. + */ +- if (bfqq->dispatched == 0) ++ BUG_ON(bfqd->busy_queues < 1); ++ if (bfqq->dispatched == 0) { + bfqq->soft_rt_next_start = + bfq_bfqq_softrt_next_start(bfqd, bfqq); +- else { ++ bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu", ++ bfqq->soft_rt_next_start); ++ } else { + /* + * The application is still waiting for the + * completion of one or more requests: +@@ -2314,7 +2850,7 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd, + * happened to be in the past. + */ + bfqq->soft_rt_next_start = +- bfq_infinity_from_now(jiffies); ++ bfq_greatest_from_now(); + /* + * Schedule an update of soft_rt_next_start to when + * the task may be discovered to be isochronous. +@@ -2324,8 +2860,9 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd, + } + + bfq_log_bfqq(bfqd, bfqq, +- "expire (%d, slow %d, num_disp %d, idle_win %d)", reason, +- slow, bfqq->dispatched, bfq_bfqq_idle_window(bfqq)); ++ "expire (%d, slow %d, num_disp %d, idle_win %d, weight %d)", ++ reason, slow, bfqq->dispatched, ++ bfq_bfqq_idle_window(bfqq), entity->weight); + + /* + * Increase, decrease or leave budget unchanged according to +@@ -2333,6 +2870,14 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd, + */ + __bfq_bfqq_recalc_budget(bfqd, bfqq, reason); + __bfq_bfqq_expire(bfqd, bfqq); ++ ++ BUG_ON(!bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED && ++ !bfq_class_idle(bfqq)); ++ ++ if (!bfq_bfqq_busy(bfqq) && ++ reason != BFQ_BFQQ_BUDGET_TIMEOUT && ++ reason != BFQ_BFQQ_BUDGET_EXHAUSTED) ++ bfq_mark_bfqq_non_blocking_wait_rq(bfqq); + } + + /* +@@ -2342,20 +2887,17 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd, + */ + static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) + { +- if (bfq_bfqq_budget_new(bfqq) || +- time_before(jiffies, bfqq->budget_timeout)) +- return false; +- return true; ++ return time_is_before_eq_jiffies(bfqq->budget_timeout); + } + + /* +- * If we expire a queue that is waiting for the arrival of a new +- * request, we may prevent the fictitious timestamp back-shifting that +- * allows the guarantees of the queue to be preserved (see [1] for +- * this tricky aspect). Hence we return true only if this condition +- * does not hold, or if the queue is slow enough to deserve only to be +- * kicked off for preserving a high throughput. +-*/ ++ * If we expire a queue that is actively waiting (i.e., with the ++ * device idled) for the arrival of a new request, then we may incur ++ * the timestamp misalignment problem described in the body of the ++ * function __bfq_activate_entity. Hence we return true only if this ++ * condition does not hold, or if the queue is slow enough to deserve ++ * only to be kicked off for preserving a high throughput. ++ */ + static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) + { + bfq_log_bfqq(bfqq->bfqd, bfqq, +@@ -2397,10 +2939,12 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) + { + struct bfq_data *bfqd = bfqq->bfqd; + bool idling_boosts_thr, idling_boosts_thr_without_issues, +- all_queues_seeky, on_hdd_and_not_all_queues_seeky, + idling_needed_for_service_guarantees, + asymmetric_scenario; + ++ if (bfqd->strict_guarantees) ++ return true; ++ + /* + * The next variable takes into account the cases where idling + * boosts the throughput. +@@ -2422,7 +2966,7 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) + */ + idling_boosts_thr = !bfqd->hw_tag || + (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) && +- bfq_bfqq_idle_window(bfqq)) ; ++ bfq_bfqq_idle_window(bfqq)); + + /* + * The value of the next variable, +@@ -2463,74 +3007,27 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) + bfqd->wr_busy_queues == 0; + + /* +- * There are then two cases where idling must be performed not ++ * There is then a case where idling must be performed not + * for throughput concerns, but to preserve service +- * guarantees. In the description of these cases, we say, for +- * short, that a queue is sequential/random if the process +- * associated to the queue issues sequential/random requests +- * (in the second case the queue may be tagged as seeky or +- * even constantly_seeky). +- * +- * To introduce the first case, we note that, since +- * bfq_bfqq_idle_window(bfqq) is false if the device is +- * NCQ-capable and bfqq is random (see +- * bfq_update_idle_window()), then, from the above two +- * assignments it follows that +- * idling_boosts_thr_without_issues is false if the device is +- * NCQ-capable and bfqq is random. Therefore, for this case, +- * device idling would never be allowed if we used just +- * idling_boosts_thr_without_issues to decide whether to allow +- * it. And, beneficially, this would imply that throughput +- * would always be boosted also with random I/O on NCQ-capable +- * HDDs. +- * +- * But we must be careful on this point, to avoid an unfair +- * treatment for bfqq. In fact, because of the same above +- * assignments, idling_boosts_thr_without_issues is, on the +- * other hand, true if 1) the device is an HDD and bfqq is +- * sequential, and 2) there are no busy weight-raised +- * queues. As a consequence, if we used just +- * idling_boosts_thr_without_issues to decide whether to idle +- * the device, then with an HDD we might easily bump into a +- * scenario where queues that are sequential and I/O-bound +- * would enjoy idling, whereas random queues would not. The +- * latter might then get a low share of the device throughput, +- * simply because the former would get many requests served +- * after being set as in service, while the latter would not. ++ * guarantees. + * +- * To address this issue, we start by setting to true a +- * sentinel variable, on_hdd_and_not_all_queues_seeky, if the +- * device is rotational and not all queues with pending or +- * in-flight requests are constantly seeky (i.e., there are +- * active sequential queues, and bfqq might then be mistreated +- * if it does not enjoy idling because it is random). +- */ +- all_queues_seeky = bfq_bfqq_constantly_seeky(bfqq) && +- bfqd->busy_in_flight_queues == +- bfqd->const_seeky_busy_in_flight_queues; +- +- on_hdd_and_not_all_queues_seeky = +- !blk_queue_nonrot(bfqd->queue) && !all_queues_seeky; +- +- /* +- * To introduce the second case where idling needs to be +- * performed to preserve service guarantees, we can note that +- * allowing the drive to enqueue more than one request at a +- * time, and hence delegating de facto final scheduling +- * decisions to the drive's internal scheduler, causes loss of +- * control on the actual request service order. In particular, +- * the critical situation is when requests from different +- * processes happens to be present, at the same time, in the +- * internal queue(s) of the drive. In such a situation, the +- * drive, by deciding the service order of the +- * internally-queued requests, does determine also the actual +- * throughput distribution among these processes. But the +- * drive typically has no notion or concern about per-process +- * throughput distribution, and makes its decisions only on a +- * per-request basis. Therefore, the service distribution +- * enforced by the drive's internal scheduler is likely to +- * coincide with the desired device-throughput distribution +- * only in a completely symmetric scenario where: ++ * To introduce this case, we can note that allowing the drive ++ * to enqueue more than one request at a time, and hence ++ * delegating de facto final scheduling decisions to the ++ * drive's internal scheduler, entails loss of control on the ++ * actual request service order. In particular, the critical ++ * situation is when requests from different processes happen ++ * to be present, at the same time, in the internal queue(s) ++ * of the drive. In such a situation, the drive, by deciding ++ * the service order of the internally-queued requests, does ++ * determine also the actual throughput distribution among ++ * these processes. But the drive typically has no notion or ++ * concern about per-process throughput distribution, and ++ * makes its decisions only on a per-request basis. Therefore, ++ * the service distribution enforced by the drive's internal ++ * scheduler is likely to coincide with the desired ++ * device-throughput distribution only in a completely ++ * symmetric scenario where: + * (i) each of these processes must get the same throughput as + * the others; + * (ii) all these processes have the same I/O pattern +@@ -2552,26 +3049,53 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) + * words, only if sub-condition (i) holds, then idling is + * allowed, and the device tends to be prevented from queueing + * many requests, possibly of several processes. The reason +- * for not controlling also sub-condition (ii) is that, first, +- * in the case of an HDD, the asymmetry in terms of types of +- * I/O patterns is already taken in to account in the above +- * sentinel variable +- * on_hdd_and_not_all_queues_seeky. Secondly, in the case of a +- * flash-based device, we prefer however to privilege +- * throughput (and idling lowers throughput for this type of +- * devices), for the following reasons: +- * 1) differently from HDDs, the service time of random +- * requests is not orders of magnitudes lower than the service +- * time of sequential requests; thus, even if processes doing +- * sequential I/O get a preferential treatment with respect to +- * others doing random I/O, the consequences are not as +- * dramatic as with HDDs; +- * 2) if a process doing random I/O does need strong +- * throughput guarantees, it is hopefully already being +- * weight-raised, or the user is likely to have assigned it a +- * higher weight than the other processes (and thus +- * sub-condition (i) is likely to be false, which triggers +- * idling). ++ * for not controlling also sub-condition (ii) is that we ++ * exploit preemption to preserve guarantees in case of ++ * symmetric scenarios, even if (ii) does not hold, as ++ * explained in the next two paragraphs. ++ * ++ * Even if a queue, say Q, is expired when it remains idle, Q ++ * can still preempt the new in-service queue if the next ++ * request of Q arrives soon (see the comments on ++ * bfq_bfqq_update_budg_for_activation). If all queues and ++ * groups have the same weight, this form of preemption, ++ * combined with the hole-recovery heuristic described in the ++ * comments on function bfq_bfqq_update_budg_for_activation, ++ * are enough to preserve a correct bandwidth distribution in ++ * the mid term, even without idling. In fact, even if not ++ * idling allows the internal queues of the device to contain ++ * many requests, and thus to reorder requests, we can rather ++ * safely assume that the internal scheduler still preserves a ++ * minimum of mid-term fairness. The motivation for using ++ * preemption instead of idling is that, by not idling, ++ * service guarantees are preserved without minimally ++ * sacrificing throughput. In other words, both a high ++ * throughput and its desired distribution are obtained. ++ * ++ * More precisely, this preemption-based, idleless approach ++ * provides fairness in terms of IOPS, and not sectors per ++ * second. This can be seen with a simple example. Suppose ++ * that there are two queues with the same weight, but that ++ * the first queue receives requests of 8 sectors, while the ++ * second queue receives requests of 1024 sectors. In ++ * addition, suppose that each of the two queues contains at ++ * most one request at a time, which implies that each queue ++ * always remains idle after it is served. Finally, after ++ * remaining idle, each queue receives very quickly a new ++ * request. It follows that the two queues are served ++ * alternatively, preempting each other if needed. This ++ * implies that, although both queues have the same weight, ++ * the queue with large requests receives a service that is ++ * 1024/8 times as high as the service received by the other ++ * queue. ++ * ++ * On the other hand, device idling is performed, and thus ++ * pure sector-domain guarantees are provided, for the ++ * following queues, which are likely to need stronger ++ * throughput guarantees: weight-raised queues, and queues ++ * with a higher weight than other queues. When such queues ++ * are active, sub-condition (i) is false, which triggers ++ * device idling. + * + * According to the above considerations, the next variable is + * true (only) if sub-condition (i) holds. To compute the +@@ -2579,7 +3103,7 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) + * the function bfq_symmetric_scenario(), but also check + * whether bfqq is being weight-raised, because + * bfq_symmetric_scenario() does not take into account also +- * weight-raised queues (see comments to ++ * weight-raised queues (see comments on + * bfq_weights_tree_add()). + * + * As a side note, it is worth considering that the above +@@ -2601,17 +3125,16 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) + * bfqq. Such a case is when bfqq became active in a burst of + * queue activations. Queues that became active during a large + * burst benefit only from throughput, as discussed in the +- * comments to bfq_handle_burst. Thus, if bfqq became active ++ * comments on bfq_handle_burst. Thus, if bfqq became active + * in a burst and not idling the device maximizes throughput, + * then the device must no be idled, because not idling the + * device provides bfqq and all other queues in the burst with +- * maximum benefit. Combining this and the two cases above, we +- * can now establish when idling is actually needed to +- * preserve service guarantees. ++ * maximum benefit. Combining this and the above case, we can ++ * now establish when idling is actually needed to preserve ++ * service guarantees. + */ + idling_needed_for_service_guarantees = +- (on_hdd_and_not_all_queues_seeky || asymmetric_scenario) && +- !bfq_bfqq_in_large_burst(bfqq); ++ asymmetric_scenario && !bfq_bfqq_in_large_burst(bfqq); + + /* + * We have now all the components we need to compute the return +@@ -2621,6 +3144,14 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) + * 2) idling either boosts the throughput (without issues), or + * is necessary to preserve service guarantees. + */ ++ bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d " ++ "wr_busy %d boosts %d IO-bound %d guar %d", ++ bfq_bfqq_sync(bfqq), idling_boosts_thr, ++ bfqd->wr_busy_queues, ++ idling_boosts_thr_without_issues, ++ bfq_bfqq_IO_bound(bfqq), ++ idling_needed_for_service_guarantees); ++ + return bfq_bfqq_sync(bfqq) && + (idling_boosts_thr_without_issues || + idling_needed_for_service_guarantees); +@@ -2632,7 +3163,7 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) + * 1) the queue must remain in service and cannot be expired, and + * 2) the device must be idled to wait for the possible arrival of a new + * request for the queue. +- * See the comments to the function bfq_bfqq_may_idle for the reasons ++ * See the comments on the function bfq_bfqq_may_idle for the reasons + * why performing device idling is the best choice to boost the throughput + * and preserve service guarantees when bfq_bfqq_may_idle itself + * returns true. +@@ -2698,9 +3229,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) + */ + bfq_clear_bfqq_wait_request(bfqq); + del_timer(&bfqd->idle_slice_timer); +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_idle_time(bfqq_group(bfqq)); +-#endif + } + goto keep_queue; + } +@@ -2745,14 +3274,11 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq) + bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change"); + + /* +- * If the queue was activated in a burst, or +- * too much time has elapsed from the beginning +- * of this weight-raising period, or the queue has +- * exceeded the acceptable number of cooperations, +- * then end weight raising. ++ * If the queue was activated in a burst, or too much ++ * time has elapsed from the beginning of this ++ * weight-raising period, then end weight raising. + */ + if (bfq_bfqq_in_large_burst(bfqq) || +- bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh || + time_is_before_jiffies(bfqq->last_wr_start_finish + + bfqq->wr_cur_max_time)) { + bfqq->last_wr_start_finish = jiffies; +@@ -2814,10 +3340,25 @@ static int bfq_dispatch_request(struct bfq_data *bfqd, + goto expire; + } + ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); + /* Finally, insert request into driver dispatch list. */ + bfq_bfqq_served(bfqq, service_to_charge); ++ ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); ++ + bfq_dispatch_insert(bfqd->queue, rq); + ++ /* ++ * If weight raising has to terminate for bfqq, then next ++ * function causes an immediate update of bfqq's weight, ++ * without waiting for next activation. As a consequence, on ++ * expiration, bfqq will be timestamped as if has never been ++ * weight-raised during this service slot, even if it has ++ * received part or even most of the service as a ++ * weight-raised queue. This inflates bfqq's timestamps, which ++ * is beneficial, as bfqq is then more willing to leave the ++ * device immediately to possible other weight-raised queues. ++ */ + bfq_update_wr_data(bfqd, bfqq); + + bfq_log_bfqq(bfqd, bfqq, +@@ -2833,9 +3374,7 @@ static int bfq_dispatch_request(struct bfq_data *bfqd, + bfqd->in_service_bic = RQ_BIC(rq); + } + +- if (bfqd->busy_queues > 1 && ((!bfq_bfqq_sync(bfqq) && +- dispatched >= bfqd->bfq_max_budget_async_rq) || +- bfq_class_idle(bfqq))) ++ if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq)) + goto expire; + + return dispatched; +@@ -2881,8 +3420,8 @@ static int bfq_forced_dispatch(struct bfq_data *bfqd) + st = bfq_entity_service_tree(&bfqq->entity); + + dispatched += __bfq_forced_dispatch_bfqq(bfqq); +- bfqq->max_budget = bfq_max_budget(bfqd); + ++ bfqq->max_budget = bfq_max_budget(bfqd); + bfq_forget_idle(st); + } + +@@ -2895,9 +3434,9 @@ static int bfq_dispatch_requests(struct request_queue *q, int force) + { + struct bfq_data *bfqd = q->elevator->elevator_data; + struct bfq_queue *bfqq; +- int max_dispatch; + + bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues); ++ + if (bfqd->busy_queues == 0) + return 0; + +@@ -2908,21 +3447,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force) + if (!bfqq) + return 0; + +- if (bfq_class_idle(bfqq)) +- max_dispatch = 1; +- +- if (!bfq_bfqq_sync(bfqq)) +- max_dispatch = bfqd->bfq_max_budget_async_rq; +- +- if (!bfq_bfqq_sync(bfqq) && bfqq->dispatched >= max_dispatch) { +- if (bfqd->busy_queues > 1) +- return 0; +- if (bfqq->dispatched >= 4 * max_dispatch) +- return 0; +- } +- +- if (bfqd->sync_flight != 0 && !bfq_bfqq_sync(bfqq)) +- return 0; ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); + + bfq_clear_bfqq_wait_request(bfqq); + BUG_ON(timer_pending(&bfqd->idle_slice_timer)); +@@ -2933,6 +3458,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force) + bfq_log_bfqq(bfqd, bfqq, "dispatched %s request", + bfq_bfqq_sync(bfqq) ? "sync" : "async"); + ++ BUG_ON(bfqq->entity.budget < bfqq->entity.service); + return 1; + } + +@@ -2949,11 +3475,11 @@ static void bfq_put_queue(struct bfq_queue *bfqq) + struct bfq_group *bfqg = bfqq_group(bfqq); + #endif + +- BUG_ON(atomic_read(&bfqq->ref) <= 0); ++ BUG_ON(bfqq->ref <= 0); + +- bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq, +- atomic_read(&bfqq->ref)); +- if (!atomic_dec_and_test(&bfqq->ref)) ++ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref); ++ bfqq->ref--; ++ if (bfqq->ref) + return; + + BUG_ON(rb_first(&bfqq->sort_list)); +@@ -3007,8 +3533,7 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) + bfq_schedule_dispatch(bfqd); + } + +- bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, +- atomic_read(&bfqq->ref)); ++ bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref); + + bfq_put_cooperator(bfqq); + +@@ -3019,26 +3544,7 @@ static void bfq_init_icq(struct io_cq *icq) + { + struct bfq_io_cq *bic = icq_to_bic(icq); + +- bic->ttime.last_end_request = jiffies; +- /* +- * A newly created bic indicates that the process has just +- * started doing I/O, and is probably mapping into memory its +- * executable and libraries: it definitely needs weight raising. +- * There is however the possibility that the process performs, +- * for a while, I/O close to some other process. EQM intercepts +- * this behavior and may merge the queue corresponding to the +- * process with some other queue, BEFORE the weight of the queue +- * is raised. Merged queues are not weight-raised (they are assumed +- * to belong to processes that benefit only from high throughput). +- * If the merge is basically the consequence of an accident, then +- * the queue will be split soon and will get back its old weight. +- * It is then important to write down somewhere that this queue +- * does need weight raising, even if it did not make it to get its +- * weight raised before being merged. To this purpose, we overload +- * the field raising_time_left and assign 1 to it, to mark the queue +- * as needing weight raising. +- */ +- bic->wr_time_left = 1; ++ bic->ttime.last_end_request = bfq_smallest_from_now(); + } + + static void bfq_exit_icq(struct io_cq *icq) +@@ -3046,21 +3552,21 @@ static void bfq_exit_icq(struct io_cq *icq) + struct bfq_io_cq *bic = icq_to_bic(icq); + struct bfq_data *bfqd = bic_to_bfqd(bic); + +- if (bic->bfqq[BLK_RW_ASYNC]) { +- bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_ASYNC]); +- bic->bfqq[BLK_RW_ASYNC] = NULL; ++ if (bic_to_bfqq(bic, false)) { ++ bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false)); ++ bic_set_bfqq(bic, NULL, false); + } + +- if (bic->bfqq[BLK_RW_SYNC]) { ++ if (bic_to_bfqq(bic, true)) { + /* + * If the bic is using a shared queue, put the reference + * taken on the io_context when the bic started using a + * shared bfq_queue. + */ +- if (bfq_bfqq_coop(bic->bfqq[BLK_RW_SYNC])) ++ if (bfq_bfqq_coop(bic_to_bfqq(bic, true))) + put_io_context(icq->ioc); +- bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]); +- bic->bfqq[BLK_RW_SYNC] = NULL; ++ bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true)); ++ bic_set_bfqq(bic, NULL, true); + } + } + +@@ -3068,7 +3574,8 @@ static void bfq_exit_icq(struct io_cq *icq) + * Update the entity prio values; note that the new values will not + * be used until the next (re)activation. + */ +-static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic) ++static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic) + { + struct task_struct *tsk = current; + int ioprio_class; +@@ -3100,7 +3607,7 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *b + break; + } + +- if (bfqq->new_ioprio < 0 || bfqq->new_ioprio >= IOPRIO_BE_NR) { ++ if (bfqq->new_ioprio >= IOPRIO_BE_NR) { + printk(KERN_CRIT "bfq_set_next_ioprio_data: new_ioprio %d\n", + bfqq->new_ioprio); + BUG(); +@@ -3108,45 +3615,39 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *b + + bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio); + bfqq->entity.prio_changed = 1; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "set_next_ioprio_data: bic_class %d prio %d class %d", ++ ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class); + } + + static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio) + { +- struct bfq_data *bfqd; +- struct bfq_queue *bfqq, *new_bfqq; +- unsigned long uninitialized_var(flags); ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ struct bfq_queue *bfqq; + int ioprio = bic->icq.ioc->ioprio; + +- bfqd = bfq_get_bfqd_locked(&(bic->icq.q->elevator->elevator_data), +- &flags); + /* + * This condition may trigger on a newly created bic, be sure to + * drop the lock before returning. + */ + if (unlikely(!bfqd) || likely(bic->ioprio == ioprio)) +- goto out; ++ return; + + bic->ioprio = ioprio; + +- bfqq = bic->bfqq[BLK_RW_ASYNC]; ++ bfqq = bic_to_bfqq(bic, false); + if (bfqq) { +- new_bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic, +- GFP_ATOMIC); +- if (new_bfqq) { +- bic->bfqq[BLK_RW_ASYNC] = new_bfqq; +- bfq_log_bfqq(bfqd, bfqq, +- "check_ioprio_change: bfqq %p %d", +- bfqq, atomic_read(&bfqq->ref)); +- bfq_put_queue(bfqq); +- } ++ bfq_put_queue(bfqq); ++ bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic); ++ bic_set_bfqq(bic, bfqq, false); ++ bfq_log_bfqq(bfqd, bfqq, ++ "check_ioprio_change: bfqq %p %d", ++ bfqq, bfqq->ref); + } + +- bfqq = bic->bfqq[BLK_RW_SYNC]; ++ bfqq = bic_to_bfqq(bic, true); + if (bfqq) + bfq_set_next_ioprio_data(bfqq, bic); +- +-out: +- bfq_put_bfqd_unlock(bfqd, &flags); + } + + static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, +@@ -3155,8 +3656,9 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, + RB_CLEAR_NODE(&bfqq->entity.rb_node); + INIT_LIST_HEAD(&bfqq->fifo); + INIT_HLIST_NODE(&bfqq->burst_list_node); ++ BUG_ON(!hlist_unhashed(&bfqq->burst_list_node)); + +- atomic_set(&bfqq->ref, 0); ++ bfqq->ref = 0; + bfqq->bfqd = bfqd; + + if (bic) +@@ -3166,6 +3668,7 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, + if (!bfq_class_idle(bfqq)) + bfq_mark_bfqq_idle_window(bfqq); + bfq_mark_bfqq_sync(bfqq); ++ bfq_mark_bfqq_just_created(bfqq); + } else + bfq_clear_bfqq_sync(bfqq); + bfq_mark_bfqq_IO_bound(bfqq); +@@ -3175,72 +3678,17 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bfqq->pid = pid; + + bfqq->wr_coeff = 1; +- bfqq->last_wr_start_finish = 0; ++ bfqq->last_wr_start_finish = bfq_smallest_from_now(); ++ bfqq->budget_timeout = bfq_smallest_from_now(); ++ bfqq->split_time = bfq_smallest_from_now(); + /* + * Set to the value for which bfqq will not be deemed as + * soft rt when it becomes backlogged. + */ +- bfqq->soft_rt_next_start = bfq_infinity_from_now(jiffies); +-} +- +-static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd, +- struct bio *bio, int is_sync, +- struct bfq_io_cq *bic, +- gfp_t gfp_mask) +-{ +- struct bfq_group *bfqg; +- struct bfq_queue *bfqq, *new_bfqq = NULL; +- struct blkcg *blkcg; +- +-retry: +- rcu_read_lock(); +- +- blkcg = bio_blkcg(bio); +- bfqg = bfq_find_alloc_group(bfqd, blkcg); +- /* bic always exists here */ +- bfqq = bic_to_bfqq(bic, is_sync); +- +- /* +- * Always try a new alloc if we fall back to the OOM bfqq +- * originally, since it should just be a temporary situation. +- */ +- if (!bfqq || bfqq == &bfqd->oom_bfqq) { +- bfqq = NULL; +- if (new_bfqq) { +- bfqq = new_bfqq; +- new_bfqq = NULL; +- } else if (gfpflags_allow_blocking(gfp_mask)) { +- rcu_read_unlock(); +- spin_unlock_irq(bfqd->queue->queue_lock); +- new_bfqq = kmem_cache_alloc_node(bfq_pool, +- gfp_mask | __GFP_ZERO, +- bfqd->queue->node); +- spin_lock_irq(bfqd->queue->queue_lock); +- if (new_bfqq) +- goto retry; +- } else { +- bfqq = kmem_cache_alloc_node(bfq_pool, +- gfp_mask | __GFP_ZERO, +- bfqd->queue->node); +- } +- +- if (bfqq) { +- bfq_init_bfqq(bfqd, bfqq, bic, current->pid, +- is_sync); +- bfq_init_entity(&bfqq->entity, bfqg); +- bfq_log_bfqq(bfqd, bfqq, "allocated"); +- } else { +- bfqq = &bfqd->oom_bfqq; +- bfq_log_bfqq(bfqd, bfqq, "using oom bfqq"); +- } +- } +- +- if (new_bfqq) +- kmem_cache_free(bfq_pool, new_bfqq); ++ bfqq->soft_rt_next_start = bfq_greatest_from_now(); + +- rcu_read_unlock(); +- +- return bfqq; ++ /* first request is almost certainly seeky */ ++ bfqq->seek_history = 1; + } + + static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, +@@ -3263,44 +3711,56 @@ static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, + } + + static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, +- struct bio *bio, int is_sync, +- struct bfq_io_cq *bic, gfp_t gfp_mask) ++ struct bio *bio, bool is_sync, ++ struct bfq_io_cq *bic) + { + const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio); + const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); + struct bfq_queue **async_bfqq = NULL; +- struct bfq_queue *bfqq = NULL; ++ struct bfq_queue *bfqq; ++ struct bfq_group *bfqg; + +- if (!is_sync) { +- struct blkcg *blkcg; +- struct bfq_group *bfqg; ++ rcu_read_lock(); + +- rcu_read_lock(); +- blkcg = bio_blkcg(bio); +- rcu_read_unlock(); +- bfqg = bfq_find_alloc_group(bfqd, blkcg); ++ bfqg = bfq_find_alloc_group(bfqd,bio_blkcg(bio)); ++ ++ if (!is_sync) { + async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class, + ioprio); + bfqq = *async_bfqq; ++ if (bfqq) ++ goto out; + } + +- if (!bfqq) +- bfqq = bfq_find_alloc_queue(bfqd, bio, is_sync, bic, gfp_mask); ++ bfqq = kmem_cache_alloc_node(bfq_pool, GFP_NOWAIT | __GFP_ZERO, ++ bfqd->queue->node); ++ ++ if (bfqq) { ++ bfq_init_bfqq(bfqd, bfqq, bic, current->pid, ++ is_sync); ++ bfq_init_entity(&bfqq->entity, bfqg); ++ bfq_log_bfqq(bfqd, bfqq, "allocated"); ++ } else { ++ bfqq = &bfqd->oom_bfqq; ++ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq"); ++ goto out; ++ } + + /* + * Pin the queue now that it's allocated, scheduler exit will + * prune it. + */ +- if (!is_sync && !(*async_bfqq)) { +- atomic_inc(&bfqq->ref); ++ if (async_bfqq) { ++ bfqq->ref++; + bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d", +- bfqq, atomic_read(&bfqq->ref)); ++ bfqq, bfqq->ref); + *async_bfqq = bfqq; + } + +- atomic_inc(&bfqq->ref); +- bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, +- atomic_read(&bfqq->ref)); ++out: ++ bfqq->ref++; ++ bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref); ++ rcu_read_unlock(); + return bfqq; + } + +@@ -3316,37 +3776,21 @@ static void bfq_update_io_thinktime(struct bfq_data *bfqd, + bic->ttime.ttime_samples; + } + +-static void bfq_update_io_seektime(struct bfq_data *bfqd, +- struct bfq_queue *bfqq, +- struct request *rq) +-{ +- sector_t sdist; +- u64 total; +- +- if (bfqq->last_request_pos < blk_rq_pos(rq)) +- sdist = blk_rq_pos(rq) - bfqq->last_request_pos; +- else +- sdist = bfqq->last_request_pos - blk_rq_pos(rq); +- +- /* +- * Don't allow the seek distance to get too large from the +- * odd fragment, pagein, etc. +- */ +- if (bfqq->seek_samples == 0) /* first request, not really a seek */ +- sdist = 0; +- else if (bfqq->seek_samples <= 60) /* second & third seek */ +- sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*1024); +- else +- sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*64); + +- bfqq->seek_samples = (7*bfqq->seek_samples + 256) / 8; +- bfqq->seek_total = (7*bfqq->seek_total + (u64)256*sdist) / 8; +- total = bfqq->seek_total + (bfqq->seek_samples/2); +- do_div(total, bfqq->seek_samples); +- bfqq->seek_mean = (sector_t)total; ++static void ++bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ sector_t sdist = 0; ++ if (bfqq->last_request_pos) { ++ if (bfqq->last_request_pos < blk_rq_pos(rq)) ++ sdist = blk_rq_pos(rq) - bfqq->last_request_pos; ++ else ++ sdist = bfqq->last_request_pos - blk_rq_pos(rq); ++ } + +- bfq_log_bfqq(bfqd, bfqq, "dist=%llu mean=%llu", (u64)sdist, +- (u64)bfqq->seek_mean); ++ bfqq->seek_history <<= 1; ++ bfqq->seek_history |= (sdist > BFQQ_SEEK_THR); + } + + /* +@@ -3364,7 +3808,8 @@ static void bfq_update_idle_window(struct bfq_data *bfqd, + return; + + /* Idle window just restored, statistics are meaningless. */ +- if (bfq_bfqq_just_split(bfqq)) ++ if (time_is_after_eq_jiffies(bfqq->split_time + ++ bfqd->bfq_wr_min_idle_time)) + return; + + enable_idle = bfq_bfqq_idle_window(bfqq); +@@ -3404,22 +3849,13 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, + + bfq_update_io_thinktime(bfqd, bic); + bfq_update_io_seektime(bfqd, bfqq, rq); +- if (!BFQQ_SEEKY(bfqq) && bfq_bfqq_constantly_seeky(bfqq)) { +- bfq_clear_bfqq_constantly_seeky(bfqq); +- if (!blk_queue_nonrot(bfqd->queue)) { +- BUG_ON(!bfqd->const_seeky_busy_in_flight_queues); +- bfqd->const_seeky_busy_in_flight_queues--; +- } +- } + if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 || + !BFQQ_SEEKY(bfqq)) + bfq_update_idle_window(bfqd, bfqq, bic); +- bfq_clear_bfqq_just_split(bfqq); + + bfq_log_bfqq(bfqd, bfqq, +- "rq_enqueued: idle_window=%d (seeky %d, mean %llu)", +- bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq), +- (long long unsigned)bfqq->seek_mean); ++ "rq_enqueued: idle_window=%d (seeky %d)", ++ bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq)); + + bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); + +@@ -3433,14 +3869,15 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, + * is small and the queue is not to be expired, then + * just exit. + * +- * In this way, if the disk is being idled to wait for +- * a new request from the in-service queue, we avoid +- * unplugging the device and committing the disk to serve +- * just a small request. On the contrary, we wait for +- * the block layer to decide when to unplug the device: +- * hopefully, new requests will be merged to this one +- * quickly, then the device will be unplugged and +- * larger requests will be dispatched. ++ * In this way, if the device is being idled to wait ++ * for a new request from the in-service queue, we ++ * avoid unplugging the device and committing the ++ * device to serve just a small request. On the ++ * contrary, we wait for the block layer to decide ++ * when to unplug the device: hopefully, new requests ++ * will be merged to this one quickly, then the device ++ * will be unplugged and larger requests will be ++ * dispatched. + */ + if (small_req && !budget_timeout) + return; +@@ -3453,9 +3890,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, + */ + bfq_clear_bfqq_wait_request(bfqq); + del_timer(&bfqd->idle_slice_timer); +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_idle_time(bfqq_group(bfqq)); +-#endif + + /* + * The queue is not empty, because a new request just +@@ -3499,27 +3934,19 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq) + */ + new_bfqq->allocated[rq_data_dir(rq)]++; + bfqq->allocated[rq_data_dir(rq)]--; +- atomic_inc(&new_bfqq->ref); ++ new_bfqq->ref++; ++ bfq_clear_bfqq_just_created(bfqq); + bfq_put_queue(bfqq); + if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq) + bfq_merge_bfqqs(bfqd, RQ_BIC(rq), + bfqq, new_bfqq); + rq->elv.priv[1] = new_bfqq; + bfqq = new_bfqq; +- } else +- bfq_bfqq_increase_failed_cooperations(bfqq); ++ } + } + + bfq_add_request(rq); + +- /* +- * Here a newly-created bfq_queue has already started a weight-raising +- * period: clear raising_time_left to prevent bfq_bfqq_save_state() +- * from assigning it a full weight-raising period. See the detailed +- * comments about this field in bfq_init_icq(). +- */ +- if (bfqq->bic) +- bfqq->bic->wr_time_left = 0; + rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; + list_add_tail(&rq->queuelist, &bfqq->fifo); + +@@ -3528,8 +3955,8 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq) + + static void bfq_update_hw_tag(struct bfq_data *bfqd) + { +- bfqd->max_rq_in_driver = max(bfqd->max_rq_in_driver, +- bfqd->rq_in_driver); ++ bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver, ++ bfqd->rq_in_driver); + + if (bfqd->hw_tag == 1) + return; +@@ -3560,43 +3987,41 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq) + bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left (%d)", + blk_rq_sectors(rq), sync); + ++ assert_spin_locked(bfqd->queue->queue_lock); + bfq_update_hw_tag(bfqd); + + BUG_ON(!bfqd->rq_in_driver); + BUG_ON(!bfqq->dispatched); + bfqd->rq_in_driver--; + bfqq->dispatched--; +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_completion(bfqq_group(bfqq), + rq_start_time_ns(rq), + rq_io_start_time_ns(rq), rq->cmd_flags); +-#endif + + if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) { ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ /* ++ * Set budget_timeout (which we overload to store the ++ * time at which the queue remains with no backlog and ++ * no outstanding request; used by the weight-raising ++ * mechanism). ++ */ ++ bfqq->budget_timeout = jiffies; ++ + bfq_weights_tree_remove(bfqd, &bfqq->entity, + &bfqd->queue_weights_tree); +- if (!blk_queue_nonrot(bfqd->queue)) { +- BUG_ON(!bfqd->busy_in_flight_queues); +- bfqd->busy_in_flight_queues--; +- if (bfq_bfqq_constantly_seeky(bfqq)) { +- BUG_ON(!bfqd-> +- const_seeky_busy_in_flight_queues); +- bfqd->const_seeky_busy_in_flight_queues--; +- } +- } + } + +- if (sync) { +- bfqd->sync_flight--; +- RQ_BIC(rq)->ttime.last_end_request = jiffies; +- } ++ RQ_BIC(rq)->ttime.last_end_request = jiffies; + + /* +- * If we are waiting to discover whether the request pattern of the +- * task associated with the queue is actually isochronous, and +- * both requisites for this condition to hold are satisfied, then +- * compute soft_rt_next_start (see the comments to the function +- * bfq_bfqq_softrt_next_start()). ++ * If we are waiting to discover whether the request pattern ++ * of the task associated with the queue is actually ++ * isochronous, and both requisites for this condition to hold ++ * are now satisfied, then compute soft_rt_next_start (see the ++ * comments on the function bfq_bfqq_softrt_next_start()). We ++ * schedule this delayed check when bfqq expires, if it still ++ * has in-flight requests. + */ + if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 && + RB_EMPTY_ROOT(&bfqq->sort_list)) +@@ -3608,10 +4033,7 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq) + * or if we want to idle in case it has no pending requests. + */ + if (bfqd->in_service_queue == bfqq) { +- if (bfq_bfqq_budget_new(bfqq)) +- bfq_set_budget_timeout(bfqd); +- +- if (bfq_bfqq_must_idle(bfqq)) { ++ if (bfqq->dispatched == 0 && bfq_bfqq_must_idle(bfqq)) { + bfq_arm_slice_timer(bfqd); + goto out; + } else if (bfq_may_expire_for_budg_timeout(bfqq)) +@@ -3682,14 +4104,14 @@ static void bfq_put_request(struct request *rq) + rq->elv.priv[1] = NULL; + + bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d", +- bfqq, atomic_read(&bfqq->ref)); ++ bfqq, bfqq->ref); + bfq_put_queue(bfqq); + } + } + + /* + * Returns NULL if a new bfqq should be allocated, or the old bfqq if this +- * was the last process referring to said bfqq. ++ * was the last process referring to that bfqq. + */ + static struct bfq_queue * + bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq) +@@ -3727,11 +4149,8 @@ static int bfq_set_request(struct request_queue *q, struct request *rq, + unsigned long flags; + bool split = false; + +- might_sleep_if(gfpflags_allow_blocking(gfp_mask)); +- +- bfq_check_ioprio_change(bic, bio); +- + spin_lock_irqsave(q->queue_lock, flags); ++ bfq_check_ioprio_change(bic, bio); + + if (!bic) + goto queue_fail; +@@ -3741,23 +4160,47 @@ static int bfq_set_request(struct request_queue *q, struct request *rq, + new_queue: + bfqq = bic_to_bfqq(bic, is_sync); + if (!bfqq || bfqq == &bfqd->oom_bfqq) { +- bfqq = bfq_get_queue(bfqd, bio, is_sync, bic, gfp_mask); ++ if (bfqq) ++ bfq_put_queue(bfqq); ++ bfqq = bfq_get_queue(bfqd, bio, is_sync, bic); ++ BUG_ON(!hlist_unhashed(&bfqq->burst_list_node)); ++ + bic_set_bfqq(bic, bfqq, is_sync); + if (split && is_sync) { ++ bfq_log_bfqq(bfqd, bfqq, ++ "set_request: was_in_list %d " ++ "was_in_large_burst %d " ++ "large burst in progress %d", ++ bic->was_in_burst_list, ++ bic->saved_in_large_burst, ++ bfqd->large_burst); ++ + if ((bic->was_in_burst_list && bfqd->large_burst) || +- bic->saved_in_large_burst) ++ bic->saved_in_large_burst) { ++ bfq_log_bfqq(bfqd, bfqq, ++ "set_request: marking in " ++ "large burst"); + bfq_mark_bfqq_in_large_burst(bfqq); +- else { +- bfq_clear_bfqq_in_large_burst(bfqq); +- if (bic->was_in_burst_list) +- hlist_add_head(&bfqq->burst_list_node, +- &bfqd->burst_list); ++ } else { ++ bfq_log_bfqq(bfqd, bfqq, ++ "set_request: clearing in " ++ "large burst"); ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ if (bic->was_in_burst_list) ++ hlist_add_head(&bfqq->burst_list_node, ++ &bfqd->burst_list); + } ++ bfqq->split_time = jiffies; + } + } else { + /* If the queue was seeky for too long, break it apart. */ + if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) { + bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq"); ++ ++ /* Update bic before losing reference to bfqq */ ++ if (bfq_bfqq_in_large_burst(bfqq)) ++ bic->saved_in_large_burst = true; ++ + bfqq = bfq_split_bfqq(bic, bfqq); + split = true; + if (!bfqq) +@@ -3766,9 +4209,8 @@ new_queue: + } + + bfqq->allocated[rw]++; +- atomic_inc(&bfqq->ref); +- bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, +- atomic_read(&bfqq->ref)); ++ bfqq->ref++; ++ bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref); + + rq->elv.priv[0] = bic; + rq->elv.priv[1] = bfqq; +@@ -3783,7 +4225,6 @@ new_queue: + if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) { + bfqq->bic = bic; + if (split) { +- bfq_mark_bfqq_just_split(bfqq); + /* + * If the queue has just been split from a shared + * queue, restore the idle window and the possible +@@ -3793,6 +4234,9 @@ new_queue: + } + } + ++ if (unlikely(bfq_bfqq_just_created(bfqq))) ++ bfq_handle_burst(bfqd, bfqq); ++ + spin_unlock_irqrestore(q->queue_lock, flags); + + return 0; +@@ -3872,6 +4316,7 @@ static void bfq_shutdown_timer_wq(struct bfq_data *bfqd) + cancel_work_sync(&bfqd->unplug_work); + } + ++#ifdef CONFIG_BFQ_GROUP_IOSCHED + static void __bfq_put_async_bfqq(struct bfq_data *bfqd, + struct bfq_queue **bfqq_ptr) + { +@@ -3880,9 +4325,9 @@ static void __bfq_put_async_bfqq(struct bfq_data *bfqd, + + bfq_log(bfqd, "put_async_bfqq: %p", bfqq); + if (bfqq) { +- bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group); ++ bfq_bfqq_move(bfqd, bfqq, root_group); + bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d", +- bfqq, atomic_read(&bfqq->ref)); ++ bfqq, bfqq->ref); + bfq_put_queue(bfqq); + *bfqq_ptr = NULL; + } +@@ -3904,6 +4349,7 @@ static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg) + + __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq); + } ++#endif + + static void bfq_exit_queue(struct elevator_queue *e) + { +@@ -3923,8 +4369,6 @@ static void bfq_exit_queue(struct elevator_queue *e) + + bfq_shutdown_timer_wq(bfqd); + +- synchronize_rcu(); +- + BUG_ON(timer_pending(&bfqd->idle_slice_timer)); + + #ifdef CONFIG_BFQ_GROUP_IOSCHED +@@ -3973,11 +4417,14 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) + * will not attempt to free it. + */ + bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0); +- atomic_inc(&bfqd->oom_bfqq.ref); ++ bfqd->oom_bfqq.ref++; + bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO; + bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE; + bfqd->oom_bfqq.entity.new_weight = + bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio); ++ ++ /* oom_bfqq does not participate to bursts */ ++ bfq_clear_bfqq_just_created(&bfqd->oom_bfqq); + /* + * Trigger weight initialization, according to ioprio, at the + * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio +@@ -3996,9 +4443,6 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) + goto out_free; + bfq_init_root_group(bfqd->root_group, bfqd); + bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group); +-#ifdef CONFIG_BFQ_GROUP_IOSCHED +- bfqd->active_numerous_groups = 0; +-#endif + + init_timer(&bfqd->idle_slice_timer); + bfqd->idle_slice_timer.function = bfq_idle_slice_timer; +@@ -4023,20 +4467,19 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) + bfqd->bfq_back_penalty = bfq_back_penalty; + bfqd->bfq_slice_idle = bfq_slice_idle; + bfqd->bfq_class_idle_last_service = 0; +- bfqd->bfq_max_budget_async_rq = bfq_max_budget_async_rq; +- bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async; +- bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync; ++ bfqd->bfq_timeout = bfq_timeout; + +- bfqd->bfq_coop_thresh = 2; +- bfqd->bfq_failed_cooperations = 7000; + bfqd->bfq_requests_within_timer = 120; + +- bfqd->bfq_large_burst_thresh = 11; +- bfqd->bfq_burst_interval = msecs_to_jiffies(500); ++ bfqd->bfq_large_burst_thresh = 8; ++ bfqd->bfq_burst_interval = msecs_to_jiffies(180); + + bfqd->low_latency = true; + +- bfqd->bfq_wr_coeff = 20; ++ /* ++ * Trade-off between responsiveness and fairness. ++ */ ++ bfqd->bfq_wr_coeff = 30; + bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300); + bfqd->bfq_wr_max_time = 0; + bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000); +@@ -4048,16 +4491,15 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) + * video. + */ + bfqd->wr_busy_queues = 0; +- bfqd->busy_in_flight_queues = 0; +- bfqd->const_seeky_busy_in_flight_queues = 0; + + /* +- * Begin by assuming, optimistically, that the device peak rate is +- * equal to the highest reference rate. ++ * Begin by assuming, optimistically, that the device is a ++ * high-speed one, and that its peak rate is equal to 2/3 of ++ * the highest reference rate. + */ + bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] * + T_fast[blk_queue_nonrot(bfqd->queue)]; +- bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)]; ++ bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)] * 2 / 3; + bfqd->device_speed = BFQ_BFQD_FAST; + + return 0; +@@ -4161,10 +4603,8 @@ SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0); + SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0); + SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 1); + SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0); +-SHOW_FUNCTION(bfq_max_budget_async_rq_show, +- bfqd->bfq_max_budget_async_rq, 0); +-SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout[BLK_RW_SYNC], 1); +-SHOW_FUNCTION(bfq_timeout_async_show, bfqd->bfq_timeout[BLK_RW_ASYNC], 1); ++SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1); ++SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0); + SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0); + SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0); + SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1); +@@ -4199,10 +4639,6 @@ STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0); + STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1, + INT_MAX, 0); + STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 1); +-STORE_FUNCTION(bfq_max_budget_async_rq_store, &bfqd->bfq_max_budget_async_rq, +- 1, INT_MAX, 0); +-STORE_FUNCTION(bfq_timeout_async_store, &bfqd->bfq_timeout[BLK_RW_ASYNC], 0, +- INT_MAX, 1); + STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0); + STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1); + STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX, +@@ -4224,10 +4660,8 @@ static ssize_t bfq_weights_store(struct elevator_queue *e, + + static unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd) + { +- u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]); +- + if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES) +- return bfq_calc_max_budget(bfqd->peak_rate, timeout); ++ return bfq_calc_max_budget(bfqd); + else + return bfq_default_max_budget; + } +@@ -4252,6 +4686,10 @@ static ssize_t bfq_max_budget_store(struct elevator_queue *e, + return ret; + } + ++/* ++ * Leaving this name to preserve name compatibility with cfq ++ * parameters, but this timeout is used for both sync and async. ++ */ + static ssize_t bfq_timeout_sync_store(struct elevator_queue *e, + const char *page, size_t count) + { +@@ -4264,13 +4702,31 @@ static ssize_t bfq_timeout_sync_store(struct elevator_queue *e, + else if (__data > INT_MAX) + __data = INT_MAX; + +- bfqd->bfq_timeout[BLK_RW_SYNC] = msecs_to_jiffies(__data); ++ bfqd->bfq_timeout = msecs_to_jiffies(__data); + if (bfqd->bfq_user_max_budget == 0) + bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd); + + return ret; + } + ++static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data > 1) ++ __data = 1; ++ if (!bfqd->strict_guarantees && __data == 1 ++ && bfqd->bfq_slice_idle < msecs_to_jiffies(8)) ++ bfqd->bfq_slice_idle = msecs_to_jiffies(8); ++ ++ bfqd->strict_guarantees = __data; ++ ++ return ret; ++} ++ + static ssize_t bfq_low_latency_store(struct elevator_queue *e, + const char *page, size_t count) + { +@@ -4297,9 +4753,8 @@ static struct elv_fs_entry bfq_attrs[] = { + BFQ_ATTR(back_seek_penalty), + BFQ_ATTR(slice_idle), + BFQ_ATTR(max_budget), +- BFQ_ATTR(max_budget_async_rq), + BFQ_ATTR(timeout_sync), +- BFQ_ATTR(timeout_async), ++ BFQ_ATTR(strict_guarantees), + BFQ_ATTR(low_latency), + BFQ_ATTR(wr_coeff), + BFQ_ATTR(wr_max_time), +@@ -4342,9 +4797,28 @@ static struct elevator_type iosched_bfq = { + .elevator_owner = THIS_MODULE, + }; + ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++static struct blkcg_policy blkcg_policy_bfq = { ++ .dfl_cftypes = bfq_blkg_files, ++ .legacy_cftypes = bfq_blkcg_legacy_files, ++ ++ .cpd_alloc_fn = bfq_cpd_alloc, ++ .cpd_init_fn = bfq_cpd_init, ++ .cpd_bind_fn = bfq_cpd_init, ++ .cpd_free_fn = bfq_cpd_free, ++ ++ .pd_alloc_fn = bfq_pd_alloc, ++ .pd_init_fn = bfq_pd_init, ++ .pd_offline_fn = bfq_pd_offline, ++ .pd_free_fn = bfq_pd_free, ++ .pd_reset_stats_fn = bfq_pd_reset_stats, ++}; ++#endif ++ + static int __init bfq_init(void) + { + int ret; ++ char msg[50] = "BFQ I/O-scheduler: v8"; + + /* + * Can be 0 on HZ < 1000 setups. +@@ -4352,9 +4826,6 @@ static int __init bfq_init(void) + if (bfq_slice_idle == 0) + bfq_slice_idle = 1; + +- if (bfq_timeout_async == 0) +- bfq_timeout_async = 1; +- + #ifdef CONFIG_BFQ_GROUP_IOSCHED + ret = blkcg_policy_register(&blkcg_policy_bfq); + if (ret) +@@ -4370,23 +4841,34 @@ static int __init bfq_init(void) + * installed on the reference devices (see the comments before the + * definitions of the two arrays). + */ +- T_slow[0] = msecs_to_jiffies(2600); +- T_slow[1] = msecs_to_jiffies(1000); +- T_fast[0] = msecs_to_jiffies(5500); +- T_fast[1] = msecs_to_jiffies(2000); ++ T_slow[0] = msecs_to_jiffies(3500); ++ T_slow[1] = msecs_to_jiffies(1500); ++ T_fast[0] = msecs_to_jiffies(8000); ++ T_fast[1] = msecs_to_jiffies(3000); + + /* +- * Thresholds that determine the switch between speed classes (see +- * the comments before the definition of the array). ++ * Thresholds that determine the switch between speed classes ++ * (see the comments before the definition of the array ++ * device_speed_thresh). These thresholds are biased towards ++ * transitions to the fast class. This is safer than the ++ * opposite bias. In fact, a wrong transition to the slow ++ * class results in short weight-raising periods, because the ++ * speed of the device then tends to be higher that the ++ * reference peak rate. On the opposite end, a wrong ++ * transition to the fast class tends to increase ++ * weight-raising periods, because of the opposite reason. + */ +- device_speed_thresh[0] = (R_fast[0] + R_slow[0]) / 2; +- device_speed_thresh[1] = (R_fast[1] + R_slow[1]) / 2; ++ device_speed_thresh[0] = (4 * R_slow[0]) / 3; ++ device_speed_thresh[1] = (4 * R_slow[1]) / 3; + + ret = elv_register(&iosched_bfq); + if (ret) + goto err_pol_unreg; + +- pr_info("BFQ I/O-scheduler: v7r11"); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ strcat(msg, " (with cgroups support)"); ++#endif ++ pr_info("%s", msg); + + return 0; + +diff --git a/block/bfq-sched.c b/block/bfq-sched.c +index a64fec1..e54b149 100644 +--- a/block/bfq-sched.c ++++ b/block/bfq-sched.c +@@ -7,9 +7,11 @@ + * Copyright (C) 2008 Fabio Checconi + * Paolo Valente + * +- * Copyright (C) 2010 Paolo Valente ++ * Copyright (C) 2016 Paolo Valente + */ + ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); ++ + #ifdef CONFIG_BFQ_GROUP_IOSCHED + #define for_each_entity(entity) \ + for (; entity ; entity = entity->parent) +@@ -22,8 +24,6 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, + int extract, + struct bfq_data *bfqd); + +-static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); +- + static void bfq_update_budget(struct bfq_entity *next_in_service) + { + struct bfq_entity *bfqg_entity; +@@ -48,6 +48,7 @@ static void bfq_update_budget(struct bfq_entity *next_in_service) + static int bfq_update_next_in_service(struct bfq_sched_data *sd) + { + struct bfq_entity *next_in_service; ++ struct bfq_queue *bfqq; + + if (sd->in_service_entity) + /* will update/requeue at the end of service */ +@@ -65,14 +66,29 @@ static int bfq_update_next_in_service(struct bfq_sched_data *sd) + + if (next_in_service) + bfq_update_budget(next_in_service); ++ else ++ goto exit; + ++ bfqq = bfq_entity_to_bfqq(next_in_service); ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "update_next_in_service: chosen this queue"); ++ else { ++ struct bfq_group *bfqg = ++ container_of(next_in_service, ++ struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "update_next_in_service: chosen this entity"); ++ } ++exit: + return 1; + } + + static void bfq_check_next_in_service(struct bfq_sched_data *sd, + struct bfq_entity *entity) + { +- BUG_ON(sd->next_in_service != entity); ++ WARN_ON(sd->next_in_service != entity); + } + #else + #define for_each_entity(entity) \ +@@ -151,20 +167,35 @@ static u64 bfq_delta(unsigned long service, unsigned long weight) + static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service) + { + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); +- ++ unsigned long long start, finish, delta ; + BUG_ON(entity->weight == 0); + + entity->finish = entity->start + + bfq_delta(service, entity->weight); + ++ start = ((entity->start>>10)*1000)>>12; ++ finish = ((entity->finish>>10)*1000)>>12; ++ delta = ((bfq_delta(service, entity->weight)>>10)*1000)>>12; ++ + if (bfqq) { + bfq_log_bfqq(bfqq->bfqd, bfqq, + "calc_finish: serv %lu, w %d", + service, entity->weight); + bfq_log_bfqq(bfqq->bfqd, bfqq, + "calc_finish: start %llu, finish %llu, delta %llu", +- entity->start, entity->finish, +- bfq_delta(service, entity->weight)); ++ start, finish, delta); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ } else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "calc_finish group: serv %lu, w %d", ++ service, entity->weight); ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "calc_finish group: start %llu, finish %llu, delta %llu", ++ start, finish, delta); ++#endif + } + } + +@@ -386,8 +417,6 @@ static void bfq_active_insert(struct bfq_service_tree *st, + BUG_ON(!bfqg); + BUG_ON(!bfqd); + bfqg->active_entities++; +- if (bfqg->active_entities == 2) +- bfqd->active_numerous_groups++; + } + #endif + } +@@ -399,7 +428,7 @@ static void bfq_active_insert(struct bfq_service_tree *st, + static unsigned short bfq_ioprio_to_weight(int ioprio) + { + BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR); +- return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - ioprio; ++ return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF ; + } + + /** +@@ -422,9 +451,9 @@ static void bfq_get_entity(struct bfq_entity *entity) + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + if (bfqq) { +- atomic_inc(&bfqq->ref); ++ bfqq->ref++; + bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", +- bfqq, atomic_read(&bfqq->ref)); ++ bfqq, bfqq->ref); + } + } + +@@ -499,10 +528,6 @@ static void bfq_active_extract(struct bfq_service_tree *st, + BUG_ON(!bfqd); + BUG_ON(!bfqg->active_entities); + bfqg->active_entities--; +- if (bfqg->active_entities == 1) { +- BUG_ON(!bfqd->active_numerous_groups); +- bfqd->active_numerous_groups--; +- } + } + #endif + } +@@ -552,7 +577,7 @@ static void bfq_forget_entity(struct bfq_service_tree *st, + if (bfqq) { + sd = entity->sched_data; + bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d", +- bfqq, atomic_read(&bfqq->ref)); ++ bfqq, bfqq->ref); + bfq_put_queue(bfqq); + } + } +@@ -628,12 +653,14 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, + if (entity->new_weight != entity->orig_weight) { + if (entity->new_weight < BFQ_MIN_WEIGHT || + entity->new_weight > BFQ_MAX_WEIGHT) { +- printk(KERN_CRIT "update_weight_prio: " +- "new_weight %d\n", ++ pr_crit("update_weight_prio: new_weight %d\n", + entity->new_weight); +- BUG(); ++ if (entity->new_weight < BFQ_MIN_WEIGHT) ++ entity->new_weight = BFQ_MIN_WEIGHT; ++ else ++ entity->new_weight = BFQ_MAX_WEIGHT; + } +- entity->orig_weight = entity->new_weight; ++ entity->orig_weight = entity->new_weight; + if (bfqq) + bfqq->ioprio = + bfq_weight_to_ioprio(entity->orig_weight); +@@ -708,7 +735,7 @@ static void bfq_bfqq_served(struct bfq_queue *bfqq, int served) + st = bfq_entity_service_tree(entity); + + entity->service += served; +- BUG_ON(entity->service > entity->budget); ++ + BUG_ON(st->wsum == 0); + + st->vtime += bfq_delta(served, st->wsum); +@@ -717,31 +744,69 @@ static void bfq_bfqq_served(struct bfq_queue *bfqq, int served) + #ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_set_start_empty_time(bfqq_group(bfqq)); + #endif +- bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served); ++ st = bfq_entity_service_tree(&bfqq->entity); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs, vtime %llu on %p", ++ served, ((st->vtime>>10)*1000)>>12, st); + } + + /** +- * bfq_bfqq_charge_full_budget - set the service to the entity budget. ++ * bfq_bfqq_charge_time - charge an amount of service equivalent to the length ++ * of the time interval during which bfqq has been in ++ * service. ++ * @bfqd: the device + * @bfqq: the queue that needs a service update. ++ * @time_ms: the amount of time during which the queue has received service ++ * ++ * If a queue does not consume its budget fast enough, then providing ++ * the queue with service fairness may impair throughput, more or less ++ * severely. For this reason, queues that consume their budget slowly ++ * are provided with time fairness instead of service fairness. This ++ * goal is achieved through the BFQ scheduling engine, even if such an ++ * engine works in the service, and not in the time domain. The trick ++ * is charging these queues with an inflated amount of service, equal ++ * to the amount of service that they would have received during their ++ * service slot if they had been fast, i.e., if their requests had ++ * been dispatched at a rate equal to the estimated peak rate. + * +- * When it's not possible to be fair in the service domain, because +- * a queue is not consuming its budget fast enough (the meaning of +- * fast depends on the timeout parameter), we charge it a full +- * budget. In this way we should obtain a sort of time-domain +- * fairness among all the seeky/slow queues. ++ * It is worth noting that time fairness can cause important ++ * distortions in terms of bandwidth distribution, on devices with ++ * internal queueing. The reason is that I/O requests dispatched ++ * during the service slot of a queue may be served after that service ++ * slot is finished, and may have a total processing time loosely ++ * correlated with the duration of the service slot. This is ++ * especially true for short service slots. + */ +-static void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq) ++static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ unsigned long time_ms) + { + struct bfq_entity *entity = &bfqq->entity; ++ int tot_serv_to_charge = entity->service; ++ unsigned int timeout_ms = jiffies_to_msecs(bfq_timeout); ++ ++ if (time_ms > 0 && time_ms < timeout_ms) ++ tot_serv_to_charge = ++ (bfqd->bfq_max_budget * time_ms) / timeout_ms; ++ ++ if (tot_serv_to_charge < entity->service) ++ tot_serv_to_charge = entity->service; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "charge_time: %lu/%u ms, %d/%d/%d sectors", ++ time_ms, timeout_ms, entity->service, ++ tot_serv_to_charge, entity->budget); + +- bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget"); ++ /* Increase budget to avoid inconsistencies */ ++ if (tot_serv_to_charge > entity->budget) ++ entity->budget = tot_serv_to_charge; + +- bfq_bfqq_served(bfqq, entity->budget - entity->service); ++ bfq_bfqq_served(bfqq, ++ max_t(int, 0, tot_serv_to_charge - entity->service)); + } + + /** + * __bfq_activate_entity - activate an entity. + * @entity: the entity being activated. ++ * @non_blocking_wait_rq: true if this entity was waiting for a request + * + * Called whenever an entity is activated, i.e., it is not active and one + * of its children receives a new request, or has to be reactivated due to +@@ -749,11 +814,16 @@ static void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq) + * service received if @entity is active) of the queue to calculate its + * timestamps. + */ +-static void __bfq_activate_entity(struct bfq_entity *entity) ++static void __bfq_activate_entity(struct bfq_entity *entity, ++ bool non_blocking_wait_rq) + { + struct bfq_sched_data *sd = entity->sched_data; + struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ bool backshifted = false; + ++ BUG_ON(!sd); ++ BUG_ON(!st); + if (entity == sd->in_service_entity) { + BUG_ON(entity->tree); + /* +@@ -771,45 +841,133 @@ static void __bfq_activate_entity(struct bfq_entity *entity) + * old start time. + */ + bfq_active_extract(st, entity); +- } else if (entity->tree == &st->idle) { +- /* +- * Must be on the idle tree, bfq_idle_extract() will +- * check for that. +- */ +- bfq_idle_extract(st, entity); +- entity->start = bfq_gt(st->vtime, entity->finish) ? +- st->vtime : entity->finish; + } else { +- /* +- * The finish time of the entity may be invalid, and +- * it is in the past for sure, otherwise the queue +- * would have been on the idle tree. +- */ +- entity->start = st->vtime; +- st->wsum += entity->weight; +- bfq_get_entity(entity); ++ unsigned long long min_vstart; ++ ++ /* See comments on bfq_fqq_update_budg_for_activation */ ++ if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) { ++ backshifted = true; ++ min_vstart = entity->finish; ++ } else ++ min_vstart = st->vtime; + +- BUG_ON(entity->on_st); +- entity->on_st = 1; ++ if (entity->tree == &st->idle) { ++ /* ++ * Must be on the idle tree, bfq_idle_extract() will ++ * check for that. ++ */ ++ bfq_idle_extract(st, entity); ++ entity->start = bfq_gt(min_vstart, entity->finish) ? ++ min_vstart : entity->finish; ++ } else { ++ /* ++ * The finish time of the entity may be invalid, and ++ * it is in the past for sure, otherwise the queue ++ * would have been on the idle tree. ++ */ ++ entity->start = min_vstart; ++ st->wsum += entity->weight; ++ bfq_get_entity(entity); ++ ++ BUG_ON(entity->on_st); ++ entity->on_st = 1; ++ } + } + + st = __bfq_entity_update_weight_prio(st, entity); + bfq_calc_finish(entity, entity->budget); ++ ++ /* ++ * If some queues enjoy backshifting for a while, then their ++ * (virtual) finish timestamps may happen to become lower and ++ * lower than the system virtual time. In particular, if ++ * these queues often happen to be idle for short time ++ * periods, and during such time periods other queues with ++ * higher timestamps happen to be busy, then the backshifted ++ * timestamps of the former queues can become much lower than ++ * the system virtual time. In fact, to serve the queues with ++ * higher timestamps while the ones with lower timestamps are ++ * idle, the system virtual time may be pushed-up to much ++ * higher values than the finish timestamps of the idle ++ * queues. As a consequence, the finish timestamps of all new ++ * or newly activated queues may end up being much larger than ++ * those of lucky queues with backshifted timestamps. The ++ * latter queues may then monopolize the device for a lot of ++ * time. This would simply break service guarantees. ++ * ++ * To reduce this problem, push up a little bit the ++ * backshifted timestamps of the queue associated with this ++ * entity (only a queue can happen to have the backshifted ++ * flag set): just enough to let the finish timestamp of the ++ * queue be equal to the current value of the system virtual ++ * time. This may introduce a little unfairness among queues ++ * with backshifted timestamps, but it does not break ++ * worst-case fairness guarantees. ++ * ++ * As a special case, if bfqq is weight-raised, push up ++ * timestamps much less, to keep very low the probability that ++ * this push up causes the backshifted finish timestamps of ++ * weight-raised queues to become higher than the backshifted ++ * finish timestamps of non weight-raised queues. ++ */ ++ if (backshifted && bfq_gt(st->vtime, entity->finish)) { ++ unsigned long delta = st->vtime - entity->finish; ++ ++ if (bfqq) ++ delta /= bfqq->wr_coeff; ++ ++ entity->start += delta; ++ entity->finish += delta; ++ ++ if (bfqq) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "__activate_entity: new queue finish %llu", ++ ((entity->finish>>10)*1000)>>12); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ } else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "__activate_entity: new group finish %llu", ++ ((entity->finish>>10)*1000)>>12); ++#endif ++ } ++ } ++ + bfq_active_insert(st, entity); ++ ++ if (bfqq) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "__activate_entity: queue %seligible in st %p", ++ entity->start <= st->vtime ? "" : "non ", st); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ } else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "__activate_entity: group %seligible in st %p", ++ entity->start <= st->vtime ? "" : "non ", st); ++#endif ++ } + } + + /** + * bfq_activate_entity - activate an entity and its ancestors if necessary. + * @entity: the entity to activate. ++ * @non_blocking_wait_rq: true if this entity was waiting for a request + * + * Activate @entity and all the entities on the path from it to the root. + */ +-static void bfq_activate_entity(struct bfq_entity *entity) ++static void bfq_activate_entity(struct bfq_entity *entity, ++ bool non_blocking_wait_rq) + { + struct bfq_sched_data *sd; + + for_each_entity(entity) { +- __bfq_activate_entity(entity); ++ BUG_ON(!entity); ++ __bfq_activate_entity(entity, non_blocking_wait_rq); + + sd = entity->sched_data; + if (!bfq_update_next_in_service(sd)) +@@ -890,23 +1048,24 @@ static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue) + + if (!__bfq_deactivate_entity(entity, requeue)) + /* +- * The parent entity is still backlogged, and +- * we don't need to update it as it is still +- * in service. ++ * next_in_service has not been changed, so ++ * no upwards update is needed + */ + break; + + if (sd->next_in_service) + /* +- * The parent entity is still backlogged and +- * the budgets on the path towards the root +- * need to be updated. ++ * The parent entity is still backlogged, ++ * because next_in_service is not NULL, and ++ * next_in_service has been updated (see ++ * comment on the body of the above if): ++ * upwards update of the schedule is needed. + */ + goto update; + + /* +- * If we reach there the parent is no more backlogged and +- * we want to propagate the dequeue upwards. ++ * If we get here, then the parent is no more backlogged and ++ * we want to propagate the deactivation upwards. + */ + requeue = 1; + } +@@ -916,9 +1075,23 @@ static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue) + update: + entity = parent; + for_each_entity(entity) { +- __bfq_activate_entity(entity); ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ __bfq_activate_entity(entity, false); + + sd = entity->sched_data; ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "invoking udpdate_next for this queue"); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, ++ struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "invoking udpdate_next for this entity"); ++ } ++#endif + if (!bfq_update_next_in_service(sd)) + break; + } +@@ -997,10 +1170,11 @@ left: + * Update the virtual time in @st and return the first eligible entity + * it contains. + */ +-static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st, +- bool force) ++static struct bfq_entity * ++__bfq_lookup_next_entity(struct bfq_service_tree *st, bool force) + { + struct bfq_entity *entity, *new_next_in_service = NULL; ++ struct bfq_queue *bfqq; + + if (RB_EMPTY_ROOT(&st->active)) + return NULL; +@@ -1009,6 +1183,24 @@ static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st, + entity = bfq_first_active_entity(st); + BUG_ON(bfq_gt(entity->start, st->vtime)); + ++ bfqq = bfq_entity_to_bfqq(entity); ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "__lookup_next: start %llu vtime %llu st %p", ++ ((entity->start>>10)*1000)>>12, ++ ((st->vtime>>10)*1000)>>12, st); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "__lookup_next: start %llu vtime %llu st %p", ++ ((entity->start>>10)*1000)>>12, ++ ((st->vtime>>10)*1000)>>12, st); ++ } ++#endif ++ + /* + * If the chosen entity does not match with the sched_data's + * next_in_service and we are forcedly serving the IDLE priority +@@ -1045,10 +1237,28 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, + BUG_ON(sd->in_service_entity); + + if (bfqd && +- jiffies - bfqd->bfq_class_idle_last_service > BFQ_CL_IDLE_TIMEOUT) { ++ jiffies - bfqd->bfq_class_idle_last_service > ++ BFQ_CL_IDLE_TIMEOUT) { + entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1, + true); + if (entity) { ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ if (bfqq) ++ bfq_log_bfqq(bfqd, bfqq, ++ "idle chosen from st %p %d", ++ st + BFQ_IOPRIO_CLASSES - 1, ++ BFQ_IOPRIO_CLASSES - 1) ; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg(bfqd, bfqg, ++ "idle chosen from st %p %d", ++ st + BFQ_IOPRIO_CLASSES - 1, ++ BFQ_IOPRIO_CLASSES - 1) ; ++ } ++#endif + i = BFQ_IOPRIO_CLASSES - 1; + bfqd->bfq_class_idle_last_service = jiffies; + sd->next_in_service = entity; +@@ -1057,6 +1267,24 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, + for (; i < BFQ_IOPRIO_CLASSES; i++) { + entity = __bfq_lookup_next_entity(st + i, false); + if (entity) { ++ if (bfqd != NULL) { ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ if (bfqq) ++ bfq_log_bfqq(bfqd, bfqq, ++ "chosen from st %p %d", ++ st + i, i) ; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg(bfqd, bfqg, ++ "chosen from st %p %d", ++ st + i, i) ; ++ } ++#endif ++ } ++ + if (extract) { + bfq_check_next_in_service(sd, entity); + bfq_active_extract(st + i, entity); +@@ -1070,6 +1298,13 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, + return entity; + } + ++static bool next_queue_may_preempt(struct bfq_data *bfqd) ++{ ++ struct bfq_sched_data *sd = &bfqd->root_group->sched_data; ++ ++ return sd->next_in_service != sd->in_service_entity; ++} ++ + /* + * Get next queue for service. + */ +@@ -1086,7 +1321,36 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd) + + sd = &bfqd->root_group->sched_data; + for (; sd ; sd = entity->my_sched_data) { ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ if (entity) { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg(bfqd, bfqg, ++ "get_next_queue: lookup in this group"); ++ } else ++ bfq_log_bfqg(bfqd, bfqd->root_group, ++ "get_next_queue: lookup in root group"); ++#endif ++ + entity = bfq_lookup_next_entity(sd, 1, bfqd); ++ ++ bfqq = bfq_entity_to_bfqq(entity); ++ if (bfqq) ++ bfq_log_bfqq(bfqd, bfqq, ++ "get_next_queue: this queue, finish %llu", ++ (((entity->finish>>10)*1000)>>10)>>2); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg(bfqd, bfqg, ++ "get_next_queue: this entity, finish %llu", ++ (((entity->finish>>10)*1000)>>10)>>2); ++ } ++#endif ++ + BUG_ON(!entity); + entity->service = 0; + } +@@ -1113,9 +1377,7 @@ static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, + { + struct bfq_entity *entity = &bfqq->entity; + +- if (bfqq == bfqd->in_service_queue) +- __bfq_bfqd_reset_in_service(bfqd); +- ++ BUG_ON(bfqq == bfqd->in_service_queue); + bfq_deactivate_entity(entity, requeue); + } + +@@ -1123,12 +1385,11 @@ static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) + { + struct bfq_entity *entity = &bfqq->entity; + +- bfq_activate_entity(entity); ++ bfq_activate_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq)); ++ bfq_clear_bfqq_non_blocking_wait_rq(bfqq); + } + +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + static void bfqg_stats_update_dequeue(struct bfq_group *bfqg); +-#endif + + /* + * Called when the bfqq no longer has requests pending, remove it from +@@ -1139,6 +1400,7 @@ static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, + { + BUG_ON(!bfq_bfqq_busy(bfqq)); + BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ BUG_ON(bfqq == bfqd->in_service_queue); + + bfq_log_bfqq(bfqd, bfqq, "del from busy"); + +@@ -1147,27 +1409,20 @@ static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, + BUG_ON(bfqd->busy_queues == 0); + bfqd->busy_queues--; + +- if (!bfqq->dispatched) { ++ if (!bfqq->dispatched) + bfq_weights_tree_remove(bfqd, &bfqq->entity, + &bfqd->queue_weights_tree); +- if (!blk_queue_nonrot(bfqd->queue)) { +- BUG_ON(!bfqd->busy_in_flight_queues); +- bfqd->busy_in_flight_queues--; +- if (bfq_bfqq_constantly_seeky(bfqq)) { +- BUG_ON(!bfqd-> +- const_seeky_busy_in_flight_queues); +- bfqd->const_seeky_busy_in_flight_queues--; +- } +- } +- } ++ + if (bfqq->wr_coeff > 1) + bfqd->wr_busy_queues--; + +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_dequeue(bfqq_group(bfqq)); +-#endif + ++ BUG_ON(bfqq->entity.budget < 0); ++ + bfq_deactivate_bfqq(bfqd, bfqq, requeue); ++ ++ BUG_ON(bfqq->entity.budget < 0); + } + + /* +@@ -1185,16 +1440,11 @@ static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq) + bfq_mark_bfqq_busy(bfqq); + bfqd->busy_queues++; + +- if (!bfqq->dispatched) { ++ if (!bfqq->dispatched) + if (bfqq->wr_coeff == 1) + bfq_weights_tree_add(bfqd, &bfqq->entity, + &bfqd->queue_weights_tree); +- if (!blk_queue_nonrot(bfqd->queue)) { +- bfqd->busy_in_flight_queues++; +- if (bfq_bfqq_constantly_seeky(bfqq)) +- bfqd->const_seeky_busy_in_flight_queues++; +- } +- } ++ + if (bfqq->wr_coeff > 1) + bfqd->wr_busy_queues++; + } +diff --git a/block/bfq.h b/block/bfq.h +index f73c942..9e76b27 100644 +--- a/block/bfq.h ++++ b/block/bfq.h +@@ -1,5 +1,5 @@ + /* +- * BFQ-v7r11 for 4.5.0: data structures and common functions prototypes. ++ * BFQ-v8 for 4.6.0: data structures and common functions prototypes. + * + * Based on ideas and code from CFQ: + * Copyright (C) 2003 Jens Axboe +@@ -28,7 +28,7 @@ + + #define BFQ_DEFAULT_QUEUE_IOPRIO 4 + +-#define BFQ_DEFAULT_GRP_WEIGHT 10 ++#define BFQ_WEIGHT_LEGACY_DFL 100 + #define BFQ_DEFAULT_GRP_IOPRIO 0 + #define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE + +@@ -36,12 +36,6 @@ struct bfq_entity; + + /** + * struct bfq_service_tree - per ioprio_class service tree. +- * @active: tree for active entities (i.e., those backlogged). +- * @idle: tree for idle entities (i.e., those not backlogged, with V <= F_i). +- * @first_idle: idle entity with minimum F_i. +- * @last_idle: idle entity with maximum F_i. +- * @vtime: scheduler virtual time. +- * @wsum: scheduler weight sum; active and idle entities contribute to it. + * + * Each service tree represents a B-WF2Q+ scheduler on its own. Each + * ioprio_class has its own independent scheduler, and so its own +@@ -49,27 +43,28 @@ struct bfq_entity; + * of the containing bfqd. + */ + struct bfq_service_tree { ++ /* tree for active entities (i.e., those backlogged) */ + struct rb_root active; ++ /* tree for idle entities (i.e., not backlogged, with V <= F_i)*/ + struct rb_root idle; + +- struct bfq_entity *first_idle; +- struct bfq_entity *last_idle; ++ struct bfq_entity *first_idle; /* idle entity with minimum F_i */ ++ struct bfq_entity *last_idle; /* idle entity with maximum F_i */ + +- u64 vtime; ++ u64 vtime; /* scheduler virtual time */ ++ /* scheduler weight sum; active and idle entities contribute to it */ + unsigned long wsum; + }; + + /** + * struct bfq_sched_data - multi-class scheduler. +- * @in_service_entity: entity in service. +- * @next_in_service: head-of-the-line entity in the scheduler. +- * @service_tree: array of service trees, one per ioprio_class. + * + * bfq_sched_data is the basic scheduler queue. It supports three +- * ioprio_classes, and can be used either as a toplevel queue or as +- * an intermediate queue on a hierarchical setup. +- * @next_in_service points to the active entity of the sched_data +- * service trees that will be scheduled next. ++ * ioprio_classes, and can be used either as a toplevel queue or as an ++ * intermediate queue on a hierarchical setup. @next_in_service ++ * points to the active entity of the sched_data service trees that ++ * will be scheduled next. It is used to reduce the number of steps ++ * needed for each hierarchical-schedule update. + * + * The supported ioprio_classes are the same as in CFQ, in descending + * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. +@@ -79,48 +74,29 @@ struct bfq_service_tree { + * All the fields are protected by the queue lock of the containing bfqd. + */ + struct bfq_sched_data { +- struct bfq_entity *in_service_entity; ++ struct bfq_entity *in_service_entity; /* entity in service */ ++ /* head-of-the-line entity in the scheduler (see comments above) */ + struct bfq_entity *next_in_service; ++ /* array of service trees, one per ioprio_class */ + struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; + }; + + /** + * struct bfq_weight_counter - counter of the number of all active entities + * with a given weight. +- * @weight: weight of the entities that this counter refers to. +- * @num_active: number of active entities with this weight. +- * @weights_node: weights tree member (see bfq_data's @queue_weights_tree +- * and @group_weights_tree). + */ + struct bfq_weight_counter { +- short int weight; +- unsigned int num_active; ++ short int weight; /* weight of the entities this counter refers to */ ++ unsigned int num_active; /* nr of active entities with this weight */ ++ /* ++ * Weights tree member (see bfq_data's @queue_weights_tree and ++ * @group_weights_tree) ++ */ + struct rb_node weights_node; + }; + + /** + * struct bfq_entity - schedulable entity. +- * @rb_node: service_tree member. +- * @weight_counter: pointer to the weight counter associated with this entity. +- * @on_st: flag, true if the entity is on a tree (either the active or +- * the idle one of its service_tree). +- * @finish: B-WF2Q+ finish timestamp (aka F_i). +- * @start: B-WF2Q+ start timestamp (aka S_i). +- * @tree: tree the entity is enqueued into; %NULL if not on a tree. +- * @min_start: minimum start time of the (active) subtree rooted at +- * this entity; used for O(log N) lookups into active trees. +- * @service: service received during the last round of service. +- * @budget: budget used to calculate F_i; F_i = S_i + @budget / @weight. +- * @weight: weight of the queue +- * @parent: parent entity, for hierarchical scheduling. +- * @my_sched_data: for non-leaf nodes in the cgroup hierarchy, the +- * associated scheduler queue, %NULL on leaf nodes. +- * @sched_data: the scheduler queue this entity belongs to. +- * @ioprio: the ioprio in use. +- * @new_weight: when a weight change is requested, the new weight value. +- * @orig_weight: original weight, used to implement weight boosting +- * @prio_changed: flag, true when the user requested a weight, ioprio or +- * ioprio_class change. + * + * A bfq_entity is used to represent either a bfq_queue (leaf node in the + * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each +@@ -147,27 +123,52 @@ struct bfq_weight_counter { + * containing bfqd. + */ + struct bfq_entity { +- struct rb_node rb_node; ++ struct rb_node rb_node; /* service_tree member */ ++ /* pointer to the weight counter associated with this entity */ + struct bfq_weight_counter *weight_counter; + ++ /* ++ * flag, true if the entity is on a tree (either the active or ++ * the idle one of its service_tree). ++ */ + int on_st; + +- u64 finish; +- u64 start; ++ u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */ ++ u64 start; /* B-WF2Q+ start timestamp (aka S_i) */ + ++ /* tree the entity is enqueued into; %NULL if not on a tree */ + struct rb_root *tree; + ++ /* ++ * minimum start time of the (active) subtree rooted at this ++ * entity; used for O(log N) lookups into active trees ++ */ + u64 min_start; + +- int service, budget; +- unsigned short weight, new_weight; ++ /* amount of service received during the last service slot */ ++ int service; ++ ++ /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */ ++ int budget; ++ ++ unsigned short weight; /* weight of the queue */ ++ unsigned short new_weight; /* next weight if a change is in progress */ ++ ++ /* original weight, used to implement weight boosting */ + unsigned short orig_weight; + ++ /* parent entity, for hierarchical scheduling */ + struct bfq_entity *parent; + ++ /* ++ * For non-leaf nodes in the hierarchy, the associated ++ * scheduler queue, %NULL on leaf nodes. ++ */ + struct bfq_sched_data *my_sched_data; ++ /* the scheduler queue this entity belongs to */ + struct bfq_sched_data *sched_data; + ++ /* flag, set to request a weight, ioprio or ioprio_class change */ + int prio_changed; + }; + +@@ -175,56 +176,6 @@ struct bfq_group; + + /** + * struct bfq_queue - leaf schedulable entity. +- * @ref: reference counter. +- * @bfqd: parent bfq_data. +- * @new_ioprio: when an ioprio change is requested, the new ioprio value. +- * @ioprio_class: the ioprio_class in use. +- * @new_ioprio_class: when an ioprio_class change is requested, the new +- * ioprio_class value. +- * @new_bfqq: shared bfq_queue if queue is cooperating with +- * one or more other queues. +- * @pos_node: request-position tree member (see bfq_group's @rq_pos_tree). +- * @pos_root: request-position tree root (see bfq_group's @rq_pos_tree). +- * @sort_list: sorted list of pending requests. +- * @next_rq: if fifo isn't expired, next request to serve. +- * @queued: nr of requests queued in @sort_list. +- * @allocated: currently allocated requests. +- * @meta_pending: pending metadata requests. +- * @fifo: fifo list of requests in sort_list. +- * @entity: entity representing this queue in the scheduler. +- * @max_budget: maximum budget allowed from the feedback mechanism. +- * @budget_timeout: budget expiration (in jiffies). +- * @dispatched: number of requests on the dispatch list or inside driver. +- * @flags: status flags. +- * @bfqq_list: node for active/idle bfqq list inside our bfqd. +- * @burst_list_node: node for the device's burst list. +- * @seek_samples: number of seeks sampled +- * @seek_total: sum of the distances of the seeks sampled +- * @seek_mean: mean seek distance +- * @last_request_pos: position of the last request enqueued +- * @requests_within_timer: number of consecutive pairs of request completion +- * and arrival, such that the queue becomes idle +- * after the completion, but the next request arrives +- * within an idle time slice; used only if the queue's +- * IO_bound has been cleared. +- * @pid: pid of the process owning the queue, used for logging purposes. +- * @last_wr_start_finish: start time of the current weight-raising period if +- * the @bfq-queue is being weight-raised, otherwise +- * finish time of the last weight-raising period +- * @wr_cur_max_time: current max raising time for this queue +- * @soft_rt_next_start: minimum time instant such that, only if a new +- * request is enqueued after this time instant in an +- * idle @bfq_queue with no outstanding requests, then +- * the task associated with the queue it is deemed as +- * soft real-time (see the comments to the function +- * bfq_bfqq_softrt_next_start()) +- * @last_idle_bklogged: time of the last transition of the @bfq_queue from +- * idle to backlogged +- * @service_from_backlogged: cumulative service received from the @bfq_queue +- * since the last transition from idle to +- * backlogged +- * @bic: pointer to the bfq_io_cq owning the bfq_queue, set to %NULL if the +- * queue is shared + * + * A bfq_queue is a leaf request queue; it can be associated with an + * io_context or more, if it is async or shared between cooperating +@@ -235,117 +186,163 @@ struct bfq_group; + * All the fields are protected by the queue lock of the containing bfqd. + */ + struct bfq_queue { +- atomic_t ref; ++ /* reference counter */ ++ int ref; ++ /* parent bfq_data */ + struct bfq_data *bfqd; + +- unsigned short ioprio, new_ioprio; +- unsigned short ioprio_class, new_ioprio_class; ++ /* current ioprio and ioprio class */ ++ unsigned short ioprio, ioprio_class; ++ /* next ioprio and ioprio class if a change is in progress */ ++ unsigned short new_ioprio, new_ioprio_class; + +- /* fields for cooperating queues handling */ ++ /* ++ * Shared bfq_queue if queue is cooperating with one or more ++ * other queues. ++ */ + struct bfq_queue *new_bfqq; ++ /* request-position tree member (see bfq_group's @rq_pos_tree) */ + struct rb_node pos_node; ++ /* request-position tree root (see bfq_group's @rq_pos_tree) */ + struct rb_root *pos_root; + ++ /* sorted list of pending requests */ + struct rb_root sort_list; ++ /* if fifo isn't expired, next request to serve */ + struct request *next_rq; ++ /* number of sync and async requests queued */ + int queued[2]; ++ /* number of sync and async requests currently allocated */ + int allocated[2]; ++ /* number of pending metadata requests */ + int meta_pending; ++ /* fifo list of requests in sort_list */ + struct list_head fifo; + ++ /* entity representing this queue in the scheduler */ + struct bfq_entity entity; + ++ /* maximum budget allowed from the feedback mechanism */ + int max_budget; ++ /* budget expiration (in jiffies) */ + unsigned long budget_timeout; + ++ /* number of requests on the dispatch list or inside driver */ + int dispatched; + +- unsigned int flags; ++ unsigned int flags; /* status flags.*/ + ++ /* node for active/idle bfqq list inside parent bfqd */ + struct list_head bfqq_list; + ++ /* bit vector: a 1 for each seeky requests in history */ ++ u32 seek_history; ++ ++ /* node for the device's burst list */ + struct hlist_node burst_list_node; + +- unsigned int seek_samples; +- u64 seek_total; +- sector_t seek_mean; ++ /* position of the last request enqueued */ + sector_t last_request_pos; + ++ /* Number of consecutive pairs of request completion and ++ * arrival, such that the queue becomes idle after the ++ * completion, but the next request arrives within an idle ++ * time slice; used only if the queue's IO_bound flag has been ++ * cleared. ++ */ + unsigned int requests_within_timer; + ++ /* pid of the process owning the queue, used for logging purposes */ + pid_t pid; ++ ++ /* ++ * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL ++ * if the queue is shared. ++ */ + struct bfq_io_cq *bic; + +- /* weight-raising fields */ ++ /* current maximum weight-raising time for this queue */ + unsigned long wr_cur_max_time; ++ /* ++ * Minimum time instant such that, only if a new request is ++ * enqueued after this time instant in an idle @bfq_queue with ++ * no outstanding requests, then the task associated with the ++ * queue it is deemed as soft real-time (see the comments on ++ * the function bfq_bfqq_softrt_next_start()) ++ */ + unsigned long soft_rt_next_start; ++ /* ++ * Start time of the current weight-raising period if ++ * the @bfq-queue is being weight-raised, otherwise ++ * finish time of the last weight-raising period. ++ */ + unsigned long last_wr_start_finish; ++ /* factor by which the weight of this queue is multiplied */ + unsigned int wr_coeff; ++ /* ++ * Time of the last transition of the @bfq_queue from idle to ++ * backlogged. ++ */ + unsigned long last_idle_bklogged; ++ /* ++ * Cumulative service received from the @bfq_queue since the ++ * last transition from idle to backlogged. ++ */ + unsigned long service_from_backlogged; ++ ++ unsigned long split_time; /* time of last split */ + }; + + /** + * struct bfq_ttime - per process thinktime stats. +- * @ttime_total: total process thinktime +- * @ttime_samples: number of thinktime samples +- * @ttime_mean: average process thinktime + */ + struct bfq_ttime { +- unsigned long last_end_request; ++ unsigned long last_end_request; /* completion time of last request */ ++ ++ unsigned long ttime_total; /* total process thinktime */ ++ unsigned long ttime_samples; /* number of thinktime samples */ ++ unsigned long ttime_mean; /* average process thinktime */ + +- unsigned long ttime_total; +- unsigned long ttime_samples; +- unsigned long ttime_mean; + }; + + /** + * struct bfq_io_cq - per (request_queue, io_context) structure. +- * @icq: associated io_cq structure +- * @bfqq: array of two process queues, the sync and the async +- * @ttime: associated @bfq_ttime struct +- * @ioprio: per (request_queue, blkcg) ioprio. +- * @blkcg_id: id of the blkcg the related io_cq belongs to. +- * @wr_time_left: snapshot of the time left before weight raising ends +- * for the sync queue associated to this process; this +- * snapshot is taken to remember this value while the weight +- * raising is suspended because the queue is merged with a +- * shared queue, and is used to set @raising_cur_max_time +- * when the queue is split from the shared queue and its +- * weight is raised again +- * @saved_idle_window: same purpose as the previous field for the idle +- * window +- * @saved_IO_bound: same purpose as the previous two fields for the I/O +- * bound classification of a queue +- * @saved_in_large_burst: same purpose as the previous fields for the +- * value of the field keeping the queue's belonging +- * to a large burst +- * @was_in_burst_list: true if the queue belonged to a burst list +- * before its merge with another cooperating queue +- * @cooperations: counter of consecutive successful queue merges underwent +- * by any of the process' @bfq_queues +- * @failed_cooperations: counter of consecutive failed queue merges of any +- * of the process' @bfq_queues + */ + struct bfq_io_cq { ++ /* associated io_cq structure */ + struct io_cq icq; /* must be the first member */ ++ /* array of two process queues, the sync and the async */ + struct bfq_queue *bfqq[2]; ++ /* associated @bfq_ttime struct */ + struct bfq_ttime ttime; ++ /* per (request_queue, blkcg) ioprio */ + int ioprio; +- + #ifdef CONFIG_BFQ_GROUP_IOSCHED +- uint64_t blkcg_id; /* the current blkcg ID */ ++ uint64_t blkcg_serial_nr; /* the current blkcg serial */ + #endif + +- unsigned int wr_time_left; ++ /* ++ * Snapshot of the idle window before merging; taken to ++ * remember this value while the queue is merged, so as to be ++ * able to restore it in case of split. ++ */ + bool saved_idle_window; ++ /* ++ * Same purpose as the previous two fields for the I/O bound ++ * classification of a queue. ++ */ + bool saved_IO_bound; + ++ /* ++ * Same purpose as the previous fields for the value of the ++ * field keeping the queue's belonging to a large burst ++ */ + bool saved_in_large_burst; ++ /* ++ * True if the queue belonged to a burst list before its merge ++ * with another cooperating queue. ++ */ + bool was_in_burst_list; +- +- unsigned int cooperations; +- unsigned int failed_cooperations; + }; + + enum bfq_device_speed { +@@ -354,224 +351,216 @@ enum bfq_device_speed { + }; + + /** +- * struct bfq_data - per device data structure. +- * @queue: request queue for the managed device. +- * @root_group: root bfq_group for the device. +- * @active_numerous_groups: number of bfq_groups containing more than one +- * active @bfq_entity. +- * @queue_weights_tree: rbtree of weight counters of @bfq_queues, sorted by +- * weight. Used to keep track of whether all @bfq_queues +- * have the same weight. The tree contains one counter +- * for each distinct weight associated to some active +- * and not weight-raised @bfq_queue (see the comments to +- * the functions bfq_weights_tree_[add|remove] for +- * further details). +- * @group_weights_tree: rbtree of non-queue @bfq_entity weight counters, sorted +- * by weight. Used to keep track of whether all +- * @bfq_groups have the same weight. The tree contains +- * one counter for each distinct weight associated to +- * some active @bfq_group (see the comments to the +- * functions bfq_weights_tree_[add|remove] for further +- * details). +- * @busy_queues: number of bfq_queues containing requests (including the +- * queue in service, even if it is idling). +- * @busy_in_flight_queues: number of @bfq_queues containing pending or +- * in-flight requests, plus the @bfq_queue in +- * service, even if idle but waiting for the +- * possible arrival of its next sync request. This +- * field is updated only if the device is rotational, +- * but used only if the device is also NCQ-capable. +- * The reason why the field is updated also for non- +- * NCQ-capable rotational devices is related to the +- * fact that the value of @hw_tag may be set also +- * later than when busy_in_flight_queues may need to +- * be incremented for the first time(s). Taking also +- * this possibility into account, to avoid unbalanced +- * increments/decrements, would imply more overhead +- * than just updating busy_in_flight_queues +- * regardless of the value of @hw_tag. +- * @const_seeky_busy_in_flight_queues: number of constantly-seeky @bfq_queues +- * (that is, seeky queues that expired +- * for budget timeout at least once) +- * containing pending or in-flight +- * requests, including the in-service +- * @bfq_queue if constantly seeky. This +- * field is updated only if the device +- * is rotational, but used only if the +- * device is also NCQ-capable (see the +- * comments to @busy_in_flight_queues). +- * @wr_busy_queues: number of weight-raised busy @bfq_queues. +- * @queued: number of queued requests. +- * @rq_in_driver: number of requests dispatched and waiting for completion. +- * @sync_flight: number of sync requests in the driver. +- * @max_rq_in_driver: max number of reqs in driver in the last +- * @hw_tag_samples completed requests. +- * @hw_tag_samples: nr of samples used to calculate hw_tag. +- * @hw_tag: flag set to one if the driver is showing a queueing behavior. +- * @budgets_assigned: number of budgets assigned. +- * @idle_slice_timer: timer set when idling for the next sequential request +- * from the queue in service. +- * @unplug_work: delayed work to restart dispatching on the request queue. +- * @in_service_queue: bfq_queue in service. +- * @in_service_bic: bfq_io_cq (bic) associated with the @in_service_queue. +- * @last_position: on-disk position of the last served request. +- * @last_budget_start: beginning of the last budget. +- * @last_idling_start: beginning of the last idle slice. +- * @peak_rate: peak transfer rate observed for a budget. +- * @peak_rate_samples: number of samples used to calculate @peak_rate. +- * @bfq_max_budget: maximum budget allotted to a bfq_queue before +- * rescheduling. +- * @active_list: list of all the bfq_queues active on the device. +- * @idle_list: list of all the bfq_queues idle on the device. +- * @bfq_fifo_expire: timeout for async/sync requests; when it expires +- * requests are served in fifo order. +- * @bfq_back_penalty: weight of backward seeks wrt forward ones. +- * @bfq_back_max: maximum allowed backward seek. +- * @bfq_slice_idle: maximum idling time. +- * @bfq_user_max_budget: user-configured max budget value +- * (0 for auto-tuning). +- * @bfq_max_budget_async_rq: maximum budget (in nr of requests) allotted to +- * async queues. +- * @bfq_timeout: timeout for bfq_queues to consume their budget; used to +- * to prevent seeky queues to impose long latencies to well +- * behaved ones (this also implies that seeky queues cannot +- * receive guarantees in the service domain; after a timeout +- * they are charged for the whole allocated budget, to try +- * to preserve a behavior reasonably fair among them, but +- * without service-domain guarantees). +- * @bfq_coop_thresh: number of queue merges after which a @bfq_queue is +- * no more granted any weight-raising. +- * @bfq_failed_cooperations: number of consecutive failed cooperation +- * chances after which weight-raising is restored +- * to a queue subject to more than bfq_coop_thresh +- * queue merges. +- * @bfq_requests_within_timer: number of consecutive requests that must be +- * issued within the idle time slice to set +- * again idling to a queue which was marked as +- * non-I/O-bound (see the definition of the +- * IO_bound flag for further details). +- * @last_ins_in_burst: last time at which a queue entered the current +- * burst of queues being activated shortly after +- * each other; for more details about this and the +- * following parameters related to a burst of +- * activations, see the comments to the function +- * @bfq_handle_burst. +- * @bfq_burst_interval: reference time interval used to decide whether a +- * queue has been activated shortly after +- * @last_ins_in_burst. +- * @burst_size: number of queues in the current burst of queue activations. +- * @bfq_large_burst_thresh: maximum burst size above which the current +- * queue-activation burst is deemed as 'large'. +- * @large_burst: true if a large queue-activation burst is in progress. +- * @burst_list: head of the burst list (as for the above fields, more details +- * in the comments to the function bfq_handle_burst). +- * @low_latency: if set to true, low-latency heuristics are enabled. +- * @bfq_wr_coeff: maximum factor by which the weight of a weight-raised +- * queue is multiplied. +- * @bfq_wr_max_time: maximum duration of a weight-raising period (jiffies). +- * @bfq_wr_rt_max_time: maximum duration for soft real-time processes. +- * @bfq_wr_min_idle_time: minimum idle period after which weight-raising +- * may be reactivated for a queue (in jiffies). +- * @bfq_wr_min_inter_arr_async: minimum period between request arrivals +- * after which weight-raising may be +- * reactivated for an already busy queue +- * (in jiffies). +- * @bfq_wr_max_softrt_rate: max service-rate for a soft real-time queue, +- * sectors per seconds. +- * @RT_prod: cached value of the product R*T used for computing the maximum +- * duration of the weight raising automatically. +- * @device_speed: device-speed class for the low-latency heuristic. +- * @oom_bfqq: fallback dummy bfqq for extreme OOM conditions. ++ * struct bfq_data - per-device data structure. + * + * All the fields are protected by the @queue lock. + */ + struct bfq_data { ++ /* request queue for the device */ + struct request_queue *queue; + ++ /* root bfq_group for the device */ + struct bfq_group *root_group; + +-#ifdef CONFIG_BFQ_GROUP_IOSCHED +- int active_numerous_groups; +-#endif +- ++ /* ++ * rbtree of weight counters of @bfq_queues, sorted by ++ * weight. Used to keep track of whether all @bfq_queues have ++ * the same weight. The tree contains one counter for each ++ * distinct weight associated to some active and not ++ * weight-raised @bfq_queue (see the comments to the functions ++ * bfq_weights_tree_[add|remove] for further details). ++ */ + struct rb_root queue_weights_tree; ++ /* ++ * rbtree of non-queue @bfq_entity weight counters, sorted by ++ * weight. Used to keep track of whether all @bfq_groups have ++ * the same weight. The tree contains one counter for each ++ * distinct weight associated to some active @bfq_group (see ++ * the comments to the functions bfq_weights_tree_[add|remove] ++ * for further details). ++ */ + struct rb_root group_weights_tree; + ++ /* ++ * Number of bfq_queues containing requests (including the ++ * queue in service, even if it is idling). ++ */ + int busy_queues; +- int busy_in_flight_queues; +- int const_seeky_busy_in_flight_queues; ++ /* number of weight-raised busy @bfq_queues */ + int wr_busy_queues; ++ /* number of queued requests */ + int queued; ++ /* number of requests dispatched and waiting for completion */ + int rq_in_driver; +- int sync_flight; + ++ /* ++ * Maximum number of requests in driver in the last ++ * @hw_tag_samples completed requests. ++ */ + int max_rq_in_driver; ++ /* number of samples used to calculate hw_tag */ + int hw_tag_samples; ++ /* flag set to one if the driver is showing a queueing behavior */ + int hw_tag; + ++ /* number of budgets assigned */ + int budgets_assigned; + ++ /* ++ * Timer set when idling (waiting) for the next request from ++ * the queue in service. ++ */ + struct timer_list idle_slice_timer; ++ /* delayed work to restart dispatching on the request queue */ + struct work_struct unplug_work; + ++ /* bfq_queue in service */ + struct bfq_queue *in_service_queue; ++ /* bfq_io_cq (bic) associated with the @in_service_queue */ + struct bfq_io_cq *in_service_bic; + ++ /* on-disk position of the last served request */ + sector_t last_position; + ++ /* beginning of the last budget */ + ktime_t last_budget_start; ++ /* beginning of the last idle slice */ + ktime_t last_idling_start; ++ /* number of samples used to calculate @peak_rate */ + int peak_rate_samples; ++ /* peak transfer rate observed for a budget */ + u64 peak_rate; ++ /* maximum budget allotted to a bfq_queue before rescheduling */ + int bfq_max_budget; + ++ /* list of all the bfq_queues active on the device */ + struct list_head active_list; ++ /* list of all the bfq_queues idle on the device */ + struct list_head idle_list; + ++ /* ++ * Timeout for async/sync requests; when it fires, requests ++ * are served in fifo order. ++ */ + unsigned int bfq_fifo_expire[2]; ++ /* weight of backward seeks wrt forward ones */ + unsigned int bfq_back_penalty; ++ /* maximum allowed backward seek */ + unsigned int bfq_back_max; ++ /* maximum idling time */ + unsigned int bfq_slice_idle; ++ /* last time CLASS_IDLE was served */ + u64 bfq_class_idle_last_service; + ++ /* user-configured max budget value (0 for auto-tuning) */ + int bfq_user_max_budget; +- int bfq_max_budget_async_rq; +- unsigned int bfq_timeout[2]; +- +- unsigned int bfq_coop_thresh; +- unsigned int bfq_failed_cooperations; ++ /* ++ * Timeout for bfq_queues to consume their budget; used to ++ * prevent seeky queues from imposing long latencies to ++ * sequential or quasi-sequential ones (this also implies that ++ * seeky queues cannot receive guarantees in the service ++ * domain; after a timeout they are charged for the time they ++ * have been in service, to preserve fairness among them, but ++ * without service-domain guarantees). ++ */ ++ unsigned int bfq_timeout; ++ ++ /* ++ * Number of consecutive requests that must be issued within ++ * the idle time slice to set again idling to a queue which ++ * was marked as non-I/O-bound (see the definition of the ++ * IO_bound flag for further details). ++ */ + unsigned int bfq_requests_within_timer; + ++ /* ++ * Force device idling whenever needed to provide accurate ++ * service guarantees, without caring about throughput ++ * issues. CAVEAT: this may even increase latencies, in case ++ * of useless idling for processes that did stop doing I/O. ++ */ ++ bool strict_guarantees; ++ ++ /* ++ * Last time at which a queue entered the current burst of ++ * queues being activated shortly after each other; for more ++ * details about this and the following parameters related to ++ * a burst of activations, see the comments on the function ++ * bfq_handle_burst. ++ */ + unsigned long last_ins_in_burst; ++ /* ++ * Reference time interval used to decide whether a queue has ++ * been activated shortly after @last_ins_in_burst. ++ */ + unsigned long bfq_burst_interval; ++ /* number of queues in the current burst of queue activations */ + int burst_size; ++ ++ /* common parent entity for the queues in the burst */ ++ struct bfq_entity *burst_parent_entity; ++ /* Maximum burst size above which the current queue-activation ++ * burst is deemed as 'large'. ++ */ + unsigned long bfq_large_burst_thresh; ++ /* true if a large queue-activation burst is in progress */ + bool large_burst; ++ /* ++ * Head of the burst list (as for the above fields, more ++ * details in the comments on the function bfq_handle_burst). ++ */ + struct hlist_head burst_list; + ++ /* if set to true, low-latency heuristics are enabled */ + bool low_latency; +- +- /* parameters of the low_latency heuristics */ ++ /* ++ * Maximum factor by which the weight of a weight-raised queue ++ * is multiplied. ++ */ + unsigned int bfq_wr_coeff; ++ /* maximum duration of a weight-raising period (jiffies) */ + unsigned int bfq_wr_max_time; ++ ++ /* Maximum weight-raising duration for soft real-time processes */ + unsigned int bfq_wr_rt_max_time; ++ /* ++ * Minimum idle period after which weight-raising may be ++ * reactivated for a queue (in jiffies). ++ */ + unsigned int bfq_wr_min_idle_time; ++ /* ++ * Minimum period between request arrivals after which ++ * weight-raising may be reactivated for an already busy async ++ * queue (in jiffies). ++ */ + unsigned long bfq_wr_min_inter_arr_async; ++ ++ /* Max service-rate for a soft real-time queue, in sectors/sec */ + unsigned int bfq_wr_max_softrt_rate; ++ /* ++ * Cached value of the product R*T, used for computing the ++ * maximum duration of weight raising automatically. ++ */ + u64 RT_prod; ++ /* device-speed class for the low-latency heuristic */ + enum bfq_device_speed device_speed; + ++ /* fallback dummy bfqq for extreme OOM conditions */ + struct bfq_queue oom_bfqq; + }; + + enum bfqq_state_flags { +- BFQ_BFQQ_FLAG_busy = 0, /* has requests or is in service */ ++ BFQ_BFQQ_FLAG_just_created = 0, /* queue just allocated */ ++ BFQ_BFQQ_FLAG_busy, /* has requests or is in service */ + BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */ ++ BFQ_BFQQ_FLAG_non_blocking_wait_rq, /* ++ * waiting for a request ++ * without idling the device ++ */ + BFQ_BFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ + BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ + BFQ_BFQQ_FLAG_idle_window, /* slice idling enabled */ + BFQ_BFQQ_FLAG_sync, /* synchronous queue */ +- BFQ_BFQQ_FLAG_budget_new, /* no completion with this budget */ + BFQ_BFQQ_FLAG_IO_bound, /* + * bfqq has timed-out at least once + * having consumed at most 2/10 of +@@ -581,17 +570,12 @@ enum bfqq_state_flags { + * bfqq activated in a large burst, + * see comments to bfq_handle_burst. + */ +- BFQ_BFQQ_FLAG_constantly_seeky, /* +- * bfqq has proved to be slow and +- * seeky until budget timeout +- */ + BFQ_BFQQ_FLAG_softrt_update, /* + * may need softrt-next-start + * update + */ + BFQ_BFQQ_FLAG_coop, /* bfqq is shared */ +- BFQ_BFQQ_FLAG_split_coop, /* shared bfqq will be split */ +- BFQ_BFQQ_FLAG_just_split, /* queue has just been split */ ++ BFQ_BFQQ_FLAG_split_coop /* shared bfqq will be split */ + }; + + #define BFQ_BFQQ_FNS(name) \ +@@ -608,25 +592,53 @@ static int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ + return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \ + } + ++BFQ_BFQQ_FNS(just_created); + BFQ_BFQQ_FNS(busy); + BFQ_BFQQ_FNS(wait_request); ++BFQ_BFQQ_FNS(non_blocking_wait_rq); + BFQ_BFQQ_FNS(must_alloc); + BFQ_BFQQ_FNS(fifo_expire); + BFQ_BFQQ_FNS(idle_window); + BFQ_BFQQ_FNS(sync); +-BFQ_BFQQ_FNS(budget_new); + BFQ_BFQQ_FNS(IO_bound); + BFQ_BFQQ_FNS(in_large_burst); +-BFQ_BFQQ_FNS(constantly_seeky); + BFQ_BFQQ_FNS(coop); + BFQ_BFQQ_FNS(split_coop); +-BFQ_BFQQ_FNS(just_split); + BFQ_BFQQ_FNS(softrt_update); + #undef BFQ_BFQQ_FNS + + /* Logging facilities. */ +-#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ +- blk_add_trace_msg((bfqd)->queue, "bfq%d " fmt, (bfqq)->pid, ##args) ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); ++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ ++ char __pbuf[128]; \ ++ \ ++ assert_spin_locked((bfqd)->queue->queue_lock); \ ++ blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \ ++ blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \ ++ (bfqq)->pid, \ ++ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ __pbuf, ##args); \ ++} while (0) ++ ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ ++ char __pbuf[128]; \ ++ \ ++ blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf)); \ ++ blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args); \ ++} while (0) ++ ++#else /* CONFIG_BFQ_GROUP_IOSCHED */ ++ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid, \ ++ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ ++ ##args) ++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) ++ ++#endif /* CONFIG_BFQ_GROUP_IOSCHED */ + + #define bfq_log(bfqd, fmt, args...) \ + blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) +@@ -640,15 +652,12 @@ enum bfqq_expiration { + BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */ + BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */ + BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */ ++ BFQ_BFQQ_PREEMPTED /* preemption in progress */ + }; + +-#ifdef CONFIG_BFQ_GROUP_IOSCHED + + struct bfqg_stats { +- /* total bytes transferred */ +- struct blkg_rwstat service_bytes; +- /* total IOs serviced, post merge */ +- struct blkg_rwstat serviced; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED + /* number of ios merged */ + struct blkg_rwstat merged; + /* total time spent on device in ns, may not be accurate w/ queueing */ +@@ -657,12 +666,8 @@ struct bfqg_stats { + struct blkg_rwstat wait_time; + /* number of IOs queued up */ + struct blkg_rwstat queued; +- /* total sectors transferred */ +- struct blkg_stat sectors; + /* total disk time and nr sectors dispatched by this group */ + struct blkg_stat time; +- /* time not charged to this cgroup */ +- struct blkg_stat unaccounted_time; + /* sum of number of ios queued across all samples */ + struct blkg_stat avg_queue_size_sum; + /* count of samples taken for average */ +@@ -680,8 +685,10 @@ struct bfqg_stats { + uint64_t start_idle_time; + uint64_t start_empty_time; + uint16_t flags; ++#endif + }; + ++#ifdef CONFIG_BFQ_GROUP_IOSCHED + /* + * struct bfq_group_data - per-blkcg storage for the blkio subsystem. + * +@@ -712,7 +719,7 @@ struct bfq_group_data { + * unused for the root group. Used to know whether there + * are groups with more than one active @bfq_entity + * (see the comments to the function +- * bfq_bfqq_must_not_expire()). ++ * bfq_bfqq_may_idle()). + * @rq_pos_tree: rbtree sorted by next_request position, used when + * determining if two or more queues have interleaving + * requests (see bfq_find_close_cooperator()). +@@ -745,7 +752,6 @@ struct bfq_group { + struct rb_root rq_pos_tree; + + struct bfqg_stats stats; +- struct bfqg_stats dead_stats; /* stats pushed from dead children */ + }; + + #else +@@ -767,11 +773,25 @@ bfq_entity_service_tree(struct bfq_entity *entity) + struct bfq_sched_data *sched_data = entity->sched_data; + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + unsigned int idx = bfqq ? bfqq->ioprio_class - 1 : +- BFQ_DEFAULT_GRP_CLASS; ++ BFQ_DEFAULT_GRP_CLASS - 1; + + BUG_ON(idx >= BFQ_IOPRIO_CLASSES); + BUG_ON(sched_data == NULL); + ++ if (bfqq) ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "entity_service_tree %p %d", ++ sched_data->service_tree + idx, idx) ; ++#ifdef CONFIG_BFQ_GROUP_IOSCHED ++ else { ++ struct bfq_group *bfqg = ++ container_of(entity, struct bfq_group, entity); ++ ++ bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg, ++ "entity_service_tree %p %d", ++ sched_data->service_tree + idx, idx) ; ++ } ++#endif + return sched_data->service_tree + idx; + } + +@@ -791,47 +811,6 @@ static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic) + return bic->icq.q->elevator->elevator_data; + } + +-/** +- * bfq_get_bfqd_locked - get a lock to a bfqd using a RCU protected pointer. +- * @ptr: a pointer to a bfqd. +- * @flags: storage for the flags to be saved. +- * +- * This function allows bfqg->bfqd to be protected by the +- * queue lock of the bfqd they reference; the pointer is dereferenced +- * under RCU, so the storage for bfqd is assured to be safe as long +- * as the RCU read side critical section does not end. After the +- * bfqd->queue->queue_lock is taken the pointer is rechecked, to be +- * sure that no other writer accessed it. If we raced with a writer, +- * the function returns NULL, with the queue unlocked, otherwise it +- * returns the dereferenced pointer, with the queue locked. +- */ +-static struct bfq_data *bfq_get_bfqd_locked(void **ptr, unsigned long *flags) +-{ +- struct bfq_data *bfqd; +- +- rcu_read_lock(); +- bfqd = rcu_dereference(*(struct bfq_data **)ptr); +- +- if (bfqd != NULL) { +- spin_lock_irqsave(bfqd->queue->queue_lock, *flags); +- if (ptr == NULL) +- printk(KERN_CRIT "get_bfqd_locked pointer NULL\n"); +- else if (*ptr == bfqd) +- goto out; +- spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); +- } +- +- bfqd = NULL; +-out: +- rcu_read_unlock(); +- return bfqd; +-} +- +-static void bfq_put_bfqd_unlock(struct bfq_data *bfqd, unsigned long *flags) +-{ +- spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); +-} +- + #ifdef CONFIG_BFQ_GROUP_IOSCHED + + static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) +@@ -857,11 +836,13 @@ static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio); + static void bfq_put_queue(struct bfq_queue *bfqq); + static void bfq_dispatch_insert(struct request_queue *q, struct request *rq); + static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, +- struct bio *bio, int is_sync, +- struct bfq_io_cq *bic, gfp_t gfp_mask); ++ struct bio *bio, bool is_sync, ++ struct bfq_io_cq *bic); + static void bfq_end_wr_async_queues(struct bfq_data *bfqd, + struct bfq_group *bfqg); ++#ifdef CONFIG_BFQ_GROUP_IOSCHED + static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); ++#endif + static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); + + #endif /* _BFQ_H */ +-- +1.9.1 +