From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx172.postini.com [74.125.245.172]) by kanga.kvack.org (Postfix) with SMTP id 924D06B002B for ; Fri, 9 Nov 2012 03:07:51 -0500 (EST) Message-ID: <509CB9D1.6060704@redhat.com> Date: Fri, 09 Nov 2012 09:07:45 +0100 From: Zdenek Kabelac MIME-Version: 1.0 Subject: Re: kswapd0: excessive CPU usage References: <507688CC.9000104@suse.cz> <106695.1349963080@turing-police.cc.vt.edu> <5076E700.2030909@suse.cz> <118079.1349978211@turing-police.cc.vt.edu> <50770905.5070904@suse.cz> <119175.1349979570@turing-police.cc.vt.edu> <5077434D.7080008@suse.cz> <50780F26.7070007@suse.cz> <20121012135726.GY29125@suse.de> <507BDD45.1070705@suse.cz> <20121015110937.GE29125@suse.de> <5093A3F4.8090108@redhat.com> <5093A631.5020209@suse.cz> <509422C3.1000803@suse.cz> <509C84ED.8090605@linux.vnet.ibm.com> In-Reply-To: <509C84ED.8090605@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Seth Jennings Cc: Jiri Slaby , Mel Gorman , Valdis.Kletnieks@vt.edu, Jiri Slaby , linux-mm@kvack.org, LKML , Andrew Morton , Rik van Riel , Robert Jennings Dne 9.11.2012 05:22, Seth Jennings napsal(a): > On 11/02/2012 02:45 PM, Jiri Slaby wrote: >> On 11/02/2012 11:53 AM, Jiri Slaby wrote: >>> On 11/02/2012 11:44 AM, Zdenek Kabelac wrote: >>>>>> Yes, applying this instead of the revert fixes the issue as well. >>>> >>>> I've applied this patch on 3.7.0-rc3 kernel - and I still see excessive >>>> CPU usage - mainly after suspend/resume >>>> >>>> Here is just simple kswapd backtrace from running kernel: >>> >>> Yup, this is what we were seeing with the former patch only too. Try to >>> apply the other one too: >>> https://patchwork.kernel.org/patch/1673231/ >>> >>> For me I would say, it is fixed by the two patches now. I won't be able >>> to report later, since I'm leaving to a conference tomorrow. >> >> Damn it. It recurred right now, with both patches applied. After I >> started a java program which consumed some more memory. Though there are >> still 2 gigs free, kswap is spinning: >> [] __cond_resched+0x2a/0x40 >> [] shrink_slab+0x1c0/0x2d0 >> [] kswapd+0x66d/0xb60 >> [] kthread+0xc0/0xd0 >> [] ret_from_fork+0x7c/0xb0 >> [] 0xffffffffffffffff > > I'm also hitting this issue in v3.7-rc4. It appears that the last > release not effected by this issue was v3.3. Bisecting the changes > included for v3.4-rc1 showed that this commit introduced the issue: > > fe2c2a106663130a5ab45cb0e3414b52df2fff0c is the first bad commit > commit fe2c2a106663130a5ab45cb0e3414b52df2fff0c > Author: Rik van Riel > Date: Wed Mar 21 16:33:51 2012 -0700 > > vmscan: reclaim at order 0 when compaction is enabled > ... > > This is plausible since the issue seems to be in the kswapd + compaction > realm. I've yet to figure out exactly what about this commit results in > kswapd spinning. > > I would be interested if someone can confirm this finding. > > -- > Seth > On my system 3.7-rc4 the problem seems to be effectively solved by revert patch: https://lkml.org/lkml/2012/11/5/308 i.e. in 2 days uptime kswapd0 eats 6 seconds which is IMHO ok - I'm not observing any busy loops on CPU with kswapd0. Zdenek -- 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/ . Don't email: email@kvack.org