From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx201.postini.com [74.125.245.201]) by kanga.kvack.org (Postfix) with SMTP id 221A66B0068 for ; Tue, 10 Jan 2012 22:27:24 -0500 (EST) Message-ID: <1326252320.5973.13.camel@hakkenden.homenet> Subject: Re: Kswapd in 3.2.0-rc5 is a CPU hog From: "Nikolay S." Date: Wed, 11 Jan 2012 07:25:20 +0400 In-Reply-To: <20120110143330.44cf1ccf.akpm@linux-foundation.org> References: <1324437036.4677.5.camel@hakkenden.homenet> <20111221095249.GA28474@tiehlicka.suse.cz> <20111221225512.GG23662@dastard> <1324630880.562.6.camel@rybalov.eng.ttk.net> <20111223102027.GB12731@dastard> <1324638242.562.15.camel@rybalov.eng.ttk.net> <20111223204503.GC12731@dastard> <20111227111543.5e486eb7.kamezawa.hiroyu@jp.fujitsu.com> <20111227035730.GA22840@barrios-laptop.redhat.com> <20111227135658.08c8016a.kamezawa.hiroyu@jp.fujitsu.com> <20120110143330.44cf1ccf.akpm@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: KAMEZAWA Hiroyuki , Minchan Kim , Dave Chinner , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org =D0=92 =D0=92=D1=82., 10/01/2012 =D0=B2 14:33 -0800, Andrew Morton =D0=BF= =D0=B8=D1=88=D0=B5=D1=82: > On Tue, 27 Dec 2011 13:56:58 +0900 > KAMEZAWA Hiroyuki wrote: >=20 > > Hmm, if I understand correctly, > >=20 > > - 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. > >=20 > > I wonder reducing to call shrink_slab() may be a help but I'm not sure > > where lock conention comes from... >=20 > Nikolay, it sounds as if this problem has only recently started > happening? Was 3.1 OK? >=20 > 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) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org