From: Andrew Morton <akpm@linux-foundation.org>
To: "Nikolay S." <nowhere@hakkenden.ath.cx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Minchan Kim <minchan@kernel.org>,
Dave Chinner <david@fromorbit.com>, Michal Hocko <mhocko@suse.cz>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: Kswapd in 3.2.0-rc5 is a CPU hog
Date: Tue, 10 Jan 2012 20:42:45 -0800 [thread overview]
Message-ID: <20120110204245.d24ed540.akpm@linux-foundation.org> (raw)
In-Reply-To: <1326252320.5973.13.camel@hakkenden.homenet>
On Wed, 11 Jan 2012 07:25:20 +0400 "Nikolay S." <nowhere@hakkenden.ath.cx> wrote:
> __ ____., 10/01/2012 __ 14:33 -0800, Andrew Morton __________:
> > On Tue, 27 Dec 2011 13:56:58 +0900
> > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> >
> > > Hmm, if I understand correctly,
> > >
> > > - dd's speed down is caused by kswapd's cpu consumption.
> > > - kswapd's cpu consumption is enlarged by shrink_slab() (by perf)
> > > - kswapd can't stop because NORMAL zone is small.
> > > - memory reclaim speed is enough because dd can't get enough cpu.
> > >
> > > I wonder reducing to call shrink_slab() may be a help but I'm not sure
> > > where lock conention comes from...
> >
> > Nikolay, it sounds as if this problem has only recently started
> > happening? Was 3.1 OK?
> >
> > If so, we should work out what we did post-3.1 to cause this.
>
> Yes, 3.1. was ok.
> Recently I have upgraded to 3.2, and I can not reproduce the problem.
> I'm now at 5 days uptime, the machine usage pattern, the software - all
> the same, but the problem is not visible anymore:
>
> PID USER S %CPU %MEM TIME+ SWAP COMMAND
> 14822 nowhere R 30 0.2 0:01.52 10m dd
> 416 root S 7 0.0 6:26.72 0 kswapd0
>
> (also, kswapd run time after 5 days is only 6,5 seconds, whereas with
> -rc5 it was 22 seconds after 5 days).
>
> I can provide similar traces to see what has changed in kswapd's
> activities (if it is of any value)
OK, thanks for the followup. I suppose we assume this is fixed unless
someone reports it in 3.2.
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next prev parent reply other threads:[~2012-01-11 4:38 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1324437036.4677.5.camel@hakkenden.homenet>
2011-12-21 9:52 ` Kswapd in 3.2.0-rc5 is a CPU hog Michal Hocko
2011-12-21 10:15 ` nowhere
2011-12-21 10:24 ` Michal Hocko
2011-12-21 10:52 ` nowhere
2011-12-21 14:06 ` Alex Elder
2011-12-21 14:19 ` nowhere
2011-12-21 22:55 ` Dave Chinner
2011-12-23 9:01 ` nowhere
2011-12-23 10:20 ` Dave Chinner
2011-12-23 11:04 ` nowhere
2011-12-23 20:45 ` Dave Chinner
2011-12-25 9:09 ` Hillf Danton
2011-12-25 10:21 ` Nikolay S.
2011-12-26 12:35 ` Hillf Danton
2011-12-27 0:20 ` KAMEZAWA Hiroyuki
2011-12-27 13:33 ` Hillf Danton
2011-12-28 0:06 ` KAMEZAWA Hiroyuki
2011-12-27 2:15 ` KAMEZAWA Hiroyuki
2011-12-27 2:50 ` Nikolay S.
2011-12-27 4:44 ` KAMEZAWA Hiroyuki
2011-12-27 6:06 ` nowhere
2011-12-28 21:33 ` Dave Chinner
2011-12-28 22:57 ` KOSAKI Motohiro
2012-01-02 7:00 ` Dave Chinner
2011-12-27 3:57 ` Minchan Kim
2011-12-27 4:56 ` KAMEZAWA Hiroyuki
2012-01-10 22:33 ` Andrew Morton
2012-01-11 3:25 ` Nikolay S.
2012-01-11 4:42 ` Andrew Morton [this message]
2012-01-11 0:33 ` Dave Chinner
2012-01-11 1:17 ` Rik van Riel
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