From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752590Ab2GYT7y (ORCPT ); Wed, 25 Jul 2012 15:59:54 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:64202 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752466Ab2GYT7w (ORCPT ); Wed, 25 Jul 2012 15:59:52 -0400 Date: Wed, 25 Jul 2012 12:59:48 -0700 From: Greg KH To: Mel Gorman Cc: Stable , Linux-MM , LKML Subject: Re: [PATCH 30/34] mm: vmscan: Do not force kswapd to scan small targets Message-ID: <20120725195948.GB5444@kroah.com> References: <1343050727-3045-1-git-send-email-mgorman@suse.de> <1343050727-3045-31-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1343050727-3045-31-git-send-email-mgorman@suse.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 23, 2012 at 02:38:43PM +0100, Mel Gorman wrote: > commit ad2b8e601099a23dffffb53f91c18d874fe98854 upstream - WARNING: this is a substitute patch. > > Stable note: Not tracked in Bugzilla. This is a substitute for an > upstream commit addressing a completely different issue that > accidentally contained an important fix. The workload this patch > helps was memcached when IO is started in the background. memcached > should stay resident but without this patch it gets swapped more > than it should. Sometimes this manifests as a drop in throughput > but mostly it was observed through /proc/vmstat. > > Commit [246e87a9: memcg: fix get_scan_count() for small targets] was > meant to fix a problem whereby small scan targets on memcg were ignored > causing priority to raise too sharply. It forced scanning to take place > if the target was small, memcg or kswapd. > > >From the time it was introduced it cause excessive reclaim by kswapd > with workloads being pushed to swap that previously would have stayed > resident. This was accidentally fixed by commit [ad2b8e60: mm: memcg: > remove optimization of keeping the root_mem_cgroup LRU lists empty] but > that patchset is not suitable for backporting. > > The original patch came with no information on what workloads it benefits > but the cost of it is obvious in that it forces scanning to take place > on lists that would otherwise have been ignored such as small anonymous > inactive lists. This patch partially reverts 246e87a9 so that small lists > are not force scanned which means that IO-intensive workloads with small > amounts of anonymous memory will not be swapped. > > Signed-off-by: Mel Gorman > --- > mm/vmscan.c | 3 --- > 1 file changed, 3 deletions(-) I don't understand this patch. The original ad2b8e601099a23dffffb53f91c18d874fe98854 commit touched the file mm/memcontrol.c and seemed to do something quite different from what you have done below. I'm all for fixing things in a different way than what was done in Linus's tree, IF there is a reason to, but the comparison between these two patches (yours and upstream) are not making any sense at all. confused, greg k-h From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx113.postini.com [74.125.245.113]) by kanga.kvack.org (Postfix) with SMTP id 075036B005D for ; Wed, 25 Jul 2012 15:59:52 -0400 (EDT) Received: by pbbrp2 with SMTP id rp2so2174810pbb.14 for ; Wed, 25 Jul 2012 12:59:52 -0700 (PDT) Date: Wed, 25 Jul 2012 12:59:48 -0700 From: Greg KH Subject: Re: [PATCH 30/34] mm: vmscan: Do not force kswapd to scan small targets Message-ID: <20120725195948.GB5444@kroah.com> References: <1343050727-3045-1-git-send-email-mgorman@suse.de> <1343050727-3045-31-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1343050727-3045-31-git-send-email-mgorman@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Stable , Linux-MM , LKML On Mon, Jul 23, 2012 at 02:38:43PM +0100, Mel Gorman wrote: > commit ad2b8e601099a23dffffb53f91c18d874fe98854 upstream - WARNING: this is a substitute patch. > > Stable note: Not tracked in Bugzilla. This is a substitute for an > upstream commit addressing a completely different issue that > accidentally contained an important fix. The workload this patch > helps was memcached when IO is started in the background. memcached > should stay resident but without this patch it gets swapped more > than it should. Sometimes this manifests as a drop in throughput > but mostly it was observed through /proc/vmstat. > > Commit [246e87a9: memcg: fix get_scan_count() for small targets] was > meant to fix a problem whereby small scan targets on memcg were ignored > causing priority to raise too sharply. It forced scanning to take place > if the target was small, memcg or kswapd. > > >From the time it was introduced it cause excessive reclaim by kswapd > with workloads being pushed to swap that previously would have stayed > resident. This was accidentally fixed by commit [ad2b8e60: mm: memcg: > remove optimization of keeping the root_mem_cgroup LRU lists empty] but > that patchset is not suitable for backporting. > > The original patch came with no information on what workloads it benefits > but the cost of it is obvious in that it forces scanning to take place > on lists that would otherwise have been ignored such as small anonymous > inactive lists. This patch partially reverts 246e87a9 so that small lists > are not force scanned which means that IO-intensive workloads with small > amounts of anonymous memory will not be swapped. > > Signed-off-by: Mel Gorman > --- > mm/vmscan.c | 3 --- > 1 file changed, 3 deletions(-) I don't understand this patch. The original ad2b8e601099a23dffffb53f91c18d874fe98854 commit touched the file mm/memcontrol.c and seemed to do something quite different from what you have done below. I'm all for fixing things in a different way than what was done in Linus's tree, IF there is a reason to, but the comparison between these two patches (yours and upstream) are not making any sense at all. confused, greg k-h -- 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