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 E9317138330 for ; Sun, 9 Oct 2016 13:25:29 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 79668E09FC; Sun, 9 Oct 2016 13:25:22 +0000 (UTC) Received: from mail-qk0-f177.google.com (mail-qk0-f177.google.com [209.85.220.177]) (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 28EC6E09AF for ; Sun, 9 Oct 2016 13:25:21 +0000 (UTC) Received: by mail-qk0-f177.google.com with SMTP id n189so79153954qke.0 for ; Sun, 09 Oct 2016 06:25:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=sDuYyExPeKIzCv2HyiRwtPnqqajTO083dOtSwMnGC9I=; b=yofOXOXQauNJS/rNJqwJu8ReBNINXnjcNQGnq+WnSCY+tU+blfIkVU7AyS64+W8dBf bqEITM9Nf0sAZYVyJa/gB3HkGkcBDMH8wetyRf+65fh2KK1I5oJV+z3DAm/uKaTxuUyj ZaQ4ogcT9dbIQTU6m/IlNWW/HZ6eDBKOPmkLBVdBdOZ9jLhOXVrpU1zbNV9wMFgy+KFh qObu5s2VLpxAhmmdDNWwVpG0cfWNLPRyimZIaldpjzhcb9Ou0Bl7gJe47X60q/HwPrwE ccWqrIGCQKm4VY0veyW4Edvk5t3jOWAocJCBr/GrI1jc49RCrpjjhZ1lZYAsXh1fvjjD KcFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=sDuYyExPeKIzCv2HyiRwtPnqqajTO083dOtSwMnGC9I=; b=FIWbBQIKVrWAssgiV8J3jY4CFekmV+5EhfgH5b8U7O/HSWlh8k6VWTkCgD5YWw14km 90E1aSsTOlXNuPn6H3kcsuNJJw3xxHt7j34cSjU1Gtd1l9NF4NU0Gnh0/BklOtcpnPzA nJJDW52T7qmdHsCeCJTqvzIdo2c4UoGuXY2ZSvLIaygdostgdepVsI9CtB7BVZXi1Gdt PLOuifpSO6gT0LhhcS4kLOj+mnFVzqHSk0yBbx+mtoZDmPsKnIR+C9rvsM8T6E8Pw23N ZgGkFYONHxm5hNluFiFT7YiqkMGUW7tHQsHFXtWHwox3yfcuT255Vy8SWcVPaZDgmS+0 1EcQ== X-Gm-Message-State: AA6/9RkTTatFKUS3jKVUZDaTTLlSHuDbEa8cTTrxEyVPDDmecQ5T1lKpkE2RSvVao3HHlcYqHFjpcQJDoM1T7A== X-Received: by 10.55.198.85 with SMTP id b82mr25900089qkj.171.1476019521163; Sun, 09 Oct 2016 06:25:21 -0700 (PDT) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Received: by 10.140.38.133 with HTTP; Sun, 9 Oct 2016 06:25:20 -0700 (PDT) In-Reply-To: <20161008212755.3eb33f3a@jupiter.sol.kaishome.de> References: <15716586.VkCrMUdRYY@serenity> <20161008212755.3eb33f3a@jupiter.sol.kaishome.de> From: Grant Date: Sun, 9 Oct 2016 06:25:20 -0700 Message-ID: Subject: Re: [gentoo-user] Re: Strive for zero swap usage? To: Gentoo mailing list Content-Type: text/plain; charset=UTF-8 X-Archives-Salt: 7703ac55-7f1d-4859-89d6-8ec3475b07f4 X-Archives-Hash: 7a37623d8f106eb3625351f17656f3e3 > Looking at the times, it looks a lot like you are having higher iowait > only at around 2:00 and 4:20 which are pretty standard cron job times. > These probably run niced or ioniced. It's normal that you are seeing > higher iowait for such processes. > > You may want to try setting your io scheduler to deadline (or even noop > if you are using a RAID controller with bbu and write cache). Since you > seem to prefer response times over throughput you should be using > deadline io scheduler anyways. Actually, don't use the default CFQ if > your server is virtualized. At least in my tests, CFQ seems to work a > lot against what virtualized IO seems to achieve. I'm using CFQ now, no virtualization. I should use CFQ if I prefer throughput and deadline for response time? > I also suggest using maybe XFS as a filesystem. Which one are you using? I'm using ext3 but I plan to move to ZFS. > If your server is a web server and it starts swapping, there is not > much you can do against it. Tuning swappiness will probably not help at > all. Get more RAM or lower your memory usage. If, for example, MySQL > runs on the same host, either move it or lower it's memory usage. > Reduce the amount of apache application processes running at the same > time (PHP, Perl, whatever), use a layered application stack: One > frontend for handling static files, one middleware server for handling > requests over to PHP and doing the request dispatch queue, and reduce > memory/IO footprint of your backend. Changing swappiness from 60 to 30 has drastically reduced swap usage but I'm not sure how much it has done for iowait and response times. I'll know more in a few days. If swap usage stays very low and I'm still not happy with the consistency of response times, I would think reducing memory usage won't help. - Grant