* [gentoo-user] IO latency issues
@ 2013-03-09 18:15 Florian Philipp
2013-03-09 18:32 ` Volker Armin Hemmann
0 siblings, 1 reply; 6+ messages in thread
From: Florian Philipp @ 2013-03-09 18:15 UTC (permalink / raw
To: Gentoo User List
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Hi list!
Whenever I do sequential IO for a long stretch of time (e.g. md5summing
40 GB), I'm experiencing high load (ca. 6 on a 4 CPU system) and
temporary freezes of most applications. For example, switching between
tabs in konsole sometimes takes more than 2 seconds.
When doing this on an ext4 filesystem, the load seems to result from
khugepaged and kswapd0 as well as some kworkers.
I think I've had similar issues with NFS over wifi but I cannot test
this now.
Today I copied 60GB from my hard disk to an USB disk formatted with
NTFS, issuing the copy command from KDE's dolphin. The freezes became so
long it was impossible to work and then X11 locked up and had to be killed.
I tried using a preemptive kernel but that didn't seem to help. blkio
and cpu cgroups didn't help either. Ionice seems to be the only solution
but while I'm okay with that, my dad won't be. Can anyone tell me what
is causing this behavior?
Throughput is good, by the way. That's why I don't suspect a driver issue.
Thanks in advance!
Florian Philipp
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* Re: [gentoo-user] IO latency issues
2013-03-09 18:15 [gentoo-user] IO latency issues Florian Philipp
@ 2013-03-09 18:32 ` Volker Armin Hemmann
2013-03-09 23:53 ` cosmoslx lin
0 siblings, 1 reply; 6+ messages in thread
From: Volker Armin Hemmann @ 2013-03-09 18:32 UTC (permalink / raw
To: gentoo-user
Am 09.03.2013 19:15, schrieb Florian Philipp:
> Hi list!
>
> Whenever I do sequential IO for a long stretch of time (e.g. md5summing
> 40 GB), I'm experiencing high load (ca. 6 on a 4 CPU system) and
> temporary freezes of most applications. For example, switching between
> tabs in konsole sometimes takes more than 2 seconds.
>
> When doing this on an ext4 filesystem, the load seems to result from
> khugepaged and kswapd0 as well as some kworkers.
>
> I think I've had similar issues with NFS over wifi but I cannot test
> this now.
>
> Today I copied 60GB from my hard disk to an USB disk formatted with
> NTFS, issuing the copy command from KDE's dolphin. The freezes became so
> long it was impossible to work and then X11 locked up and had to be killed.
>
> I tried using a preemptive kernel but that didn't seem to help. blkio
> and cpu cgroups didn't help either. Ionice seems to be the only solution
> but while I'm okay with that, my dad won't be. Can anyone tell me what
> is causing this behavior?
>
> Throughput is good, by the way. That's why I don't suspect a driver issue.
>
> Thanks in advance!
> Florian Philipp
>
congratulation. You hit 'the bug'. Been around for ages, but for magical
reasons kernel dev are unable to see or unable to do something about it.
If you are using a vanilla kernel, posting on lkml might be the right
thing to do.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [gentoo-user] IO latency issues
2013-03-09 18:32 ` Volker Armin Hemmann
@ 2013-03-09 23:53 ` cosmoslx lin
2013-03-10 12:48 ` Florian Philipp
0 siblings, 1 reply; 6+ messages in thread
From: cosmoslx lin @ 2013-03-09 23:53 UTC (permalink / raw
To: gentoo-user
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I have try the BFQ patch outside of the kernel mainline, it works well.
Maybe you would like to see:
http://algo.ing.unimo.it/people/paolo/disk_sched/
Also there is a 15-minute demo of the performance of BFQ:
http://youtu.be/J-e7LnJblm8
2013/3/10 Volker Armin Hemmann <volkerarmin@googlemail.com>
> Am 09.03.2013 19:15, schrieb Florian Philipp:
> > Hi list!
> >
> > Whenever I do sequential IO for a long stretch of time (e.g. md5summing
> > 40 GB), I'm experiencing high load (ca. 6 on a 4 CPU system) and
> > temporary freezes of most applications. For example, switching between
> > tabs in konsole sometimes takes more than 2 seconds.
> >
> > When doing this on an ext4 filesystem, the load seems to result from
> > khugepaged and kswapd0 as well as some kworkers.
> >
> > I think I've had similar issues with NFS over wifi but I cannot test
> > this now.
> >
> > Today I copied 60GB from my hard disk to an USB disk formatted with
> > NTFS, issuing the copy command from KDE's dolphin. The freezes became so
> > long it was impossible to work and then X11 locked up and had to be
> killed.
> >
> > I tried using a preemptive kernel but that didn't seem to help. blkio
> > and cpu cgroups didn't help either. Ionice seems to be the only solution
> > but while I'm okay with that, my dad won't be. Can anyone tell me what
> > is causing this behavior?
> >
> > Throughput is good, by the way. That's why I don't suspect a driver
> issue.
> >
> > Thanks in advance!
> > Florian Philipp
> >
> congratulation. You hit 'the bug'. Been around for ages, but for magical
> reasons kernel dev are unable to see or unable to do something about it.
> If you are using a vanilla kernel, posting on lkml might be the right
> thing to do.
>
>
--
Best regards!
------------------------------------------------
Yu-yu Lin(林育宇)
The Guangdong Key Laboratory of Information Security Technology (IST),
School of Information Science and Technology,
Sun Yat-sen (Zhongshan) University (中山大学),
Guangzhou,P.R.China.
Email: cosmoslx@gmail.com
------------------------------------------------ <cosmoslx@gmail.com>
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [gentoo-user] IO latency issues
2013-03-09 23:53 ` cosmoslx lin
@ 2013-03-10 12:48 ` Florian Philipp
2013-03-10 22:23 ` Florian Philipp
0 siblings, 1 reply; 6+ messages in thread
From: Florian Philipp @ 2013-03-10 12:48 UTC (permalink / raw
To: gentoo-user
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Am 10.03.2013 00:53, schrieb cosmoslx lin:>
> 2013/3/10 Volker Armin Hemmann <volkerarmin@googlemail.com
> <mailto:volkerarmin@googlemail.com>>
>
> Am 09.03.2013 19:15, schrieb Florian Philipp:
> > Hi list!
> >
> > Whenever I do sequential IO for a long stretch of time (e.g.
> md5summing
> > 40 GB), I'm experiencing high load (ca. 6 on a 4 CPU system) and
> > temporary freezes of most applications. For example, switching between
> > tabs in konsole sometimes takes more than 2 seconds.
> >
[...]
> >
> congratulation. You hit 'the bug'. Been around for ages, but for magical
> reasons kernel dev are unable to see or unable to do something about it.
> If you are using a vanilla kernel, posting on lkml might be the right
> thing to do.
>
> I have try the BFQ patch outside of the kernel mainline, it works well.
> Maybe you would like to see:
> http://algo.ing.unimo.it/people/paolo/disk_sched/
>
Thanks. I'll try pf-sources which should to include that patch set.
Regards,
Florian Philipp
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [gentoo-user] IO latency issues
2013-03-10 12:48 ` Florian Philipp
@ 2013-03-10 22:23 ` Florian Philipp
2013-03-11 16:00 ` cosmoslx lin
0 siblings, 1 reply; 6+ messages in thread
From: Florian Philipp @ 2013-03-10 22:23 UTC (permalink / raw
To: gentoo-user
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Am 10.03.2013 13:48, schrieb Florian Philipp:
> Am 10.03.2013 00:53, schrieb cosmoslx lin:>
>> 2013/3/10 Volker Armin Hemmann <volkerarmin@googlemail.com
>> <mailto:volkerarmin@googlemail.com>>
>>
>> Am 09.03.2013 19:15, schrieb Florian Philipp:
>> > Hi list!
>> >
>> > Whenever I do sequential IO for a long stretch of time (e.g.
>> md5summing
>> > 40 GB), I'm experiencing high load (ca. 6 on a 4 CPU system) and
>> > temporary freezes of most applications. For example, switching between
>> > tabs in konsole sometimes takes more than 2 seconds.
>> >
> [...]
>> >
>> congratulation. You hit 'the bug'. Been around for ages, but for magical
>> reasons kernel dev are unable to see or unable to do something about it.
>> If you are using a vanilla kernel, posting on lkml might be the right
>> thing to do.
>>
>> I have try the BFQ patch outside of the kernel mainline, it works well.
>> Maybe you would like to see:
>> http://algo.ing.unimo.it/people/paolo/disk_sched/
>>
>
> Thanks. I'll try pf-sources which should to include that patch set.
>
> Regards,
> Florian Philipp
>
pf-sources (only BFQ enabled, not BFS) helped somewhat. kswapd still
likes to keep one CPU busy when IO is happening but I suspect cleancache
to be the culprit for that. I'll test without it later.
Regards,
Florian Philipp
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [gentoo-user] IO latency issues
2013-03-10 22:23 ` Florian Philipp
@ 2013-03-11 16:00 ` cosmoslx lin
0 siblings, 0 replies; 6+ messages in thread
From: cosmoslx lin @ 2013-03-11 16:00 UTC (permalink / raw
To: gentoo-user
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maybe it will be fixed in kernel 3.9
http://www.phoronix.com/scan.php?page=news_item&px=MTMxNzA
2013/3/11 Florian Philipp <lists@binarywings.net>
> Am 10.03.2013 13:48, schrieb Florian Philipp:
> > Am 10.03.2013 00:53, schrieb cosmoslx lin:>
> >> 2013/3/10 Volker Armin Hemmann <volkerarmin@googlemail.com
> >> <mailto:volkerarmin@googlemail.com>>
> >>
> >> Am 09.03.2013 19:15, schrieb Florian Philipp:
> >> > Hi list!
> >> >
> >> > Whenever I do sequential IO for a long stretch of time (e.g.
> >> md5summing
> >> > 40 GB), I'm experiencing high load (ca. 6 on a 4 CPU system) and
> >> > temporary freezes of most applications. For example, switching
> between
> >> > tabs in konsole sometimes takes more than 2 seconds.
> >> >
> > [...]
> >> >
> >> congratulation. You hit 'the bug'. Been around for ages, but for
> magical
> >> reasons kernel dev are unable to see or unable to do something
> about it.
> >> If you are using a vanilla kernel, posting on lkml might be the
> right
> >> thing to do.
> >>
> >> I have try the BFQ patch outside of the kernel mainline, it works well.
> >> Maybe you would like to see:
> >> http://algo.ing.unimo.it/people/paolo/disk_sched/
> >>
> >
> > Thanks. I'll try pf-sources which should to include that patch set.
> >
> > Regards,
> > Florian Philipp
> >
>
> pf-sources (only BFQ enabled, not BFS) helped somewhat. kswapd still
> likes to keep one CPU busy when IO is happening but I suspect cleancache
> to be the culprit for that. I'll test without it later.
>
> Regards,
> Florian Philipp
>
>
>
--
Best regards!
------------------------------------------------
Yu-yu Lin(林育宇)
The Guangdong Key Laboratory of Information Security Technology (IST),
School of Information Science and Technology,
Sun Yat-sen (Zhongshan) University (中山大学),
Guangzhou,P.R.China.
Email: cosmoslx@gmail.com
------------------------------------------------ <cosmoslx@gmail.com>
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-03-09 18:15 [gentoo-user] IO latency issues Florian Philipp
2013-03-09 18:32 ` Volker Armin Hemmann
2013-03-09 23:53 ` cosmoslx lin
2013-03-10 12:48 ` Florian Philipp
2013-03-10 22:23 ` Florian Philipp
2013-03-11 16:00 ` cosmoslx lin
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