Messages in this thread | | | Subject | Re: Kswapd in 3.2.0-rc5 is a CPU hog | From | "Nikolay S." <> | Date | Wed, 11 Jan 2012 07:25:20 +0400 |
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В Вт., 10/01/2012 в 14:33 -0800, Andrew Morton пишет: > 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)
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