From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754213Ab2EUHMe (ORCPT ); Mon, 21 May 2012 03:12:34 -0400 Received: from alpha.arachsys.com ([91.203.57.7]:49694 "EHLO alpha.arachsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751885Ab2EUHMd (ORCPT ); Mon, 21 May 2012 03:12:33 -0400 Date: Mon, 21 May 2012 08:12:26 +0100 From: Richard Davies To: Rik van Riel Cc: KOSAKI Motohiro , Satoru Moriya , Jerome Marchand , "jweiner@redhat.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "lwoodman@redhat.com" , "shaohua.li@intel.com" , "dle-develop@lists.sourceforge.net" , Seiji Aguchi , Minchan Kim Subject: Re: [RFC][PATCH] avoid swapping out with swappiness==0 Message-ID: <20120521071226.GJ29495@alpha.arachsys.com> References: <65795E11DBF1E645A09CEC7EAEE94B9CB951A45F@USINDEVS02.corp.hds.com> <20120424082019.GA18395@alpha.arachsys.com> <65795E11DBF1E645A09CEC7EAEE94B9C014649EC4D@USINDEVS02.corp.hds.com> <20120426142643.GA18863@alpha.arachsys.com> <4FA82C11.2030805@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FA82C11.2030805@redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Satoru, Rik van Riel wrote: > KOSAKI Motohiro wrote: > > Richard Davies wrote: > > >Satoru Moriya wrote: > > > > > I have run into problems with heavy swapping with swappiness==0 and > > > > > was pointed to this thread ( > > > > > http://marc.info/?l=linux-mm&m=133522782307215 ) > > > > > > > > Did you test this patch with your workload? > > > > > > I haven't yet tested this patch. It takes a long time since these are > > > production machines, and the bug itself takes several weeks of > > > production use to really show up. > > > > > > Rik van Riel has pointed out a lot of VM tweaks that he put into 3.4: > > > http://marc.info/?l=linux-mm&m=133536506926326 > > > > > > My intention is to reboot half of our machines into plain 3.4 once it > > > is out, and half onto 3.4 + your patch. > > > > > > Then we can compare behaviour. > > > > > > Will your patch apply cleanly on 3.4? > > > > Note. This patch doesn't solve your issue. This patch mean, > > when occuring very few swap io, it change to 0. But you said > > you are seeing eager swap io. As Dave already pointed out, your > > machine have buffer head issue. > > > > So, this thread is pointless. > > Running KVM guests directly off block devices results in a lot > of buffer cache. > > I suspect that this patch will in fact fix Richard's issue. > > The patch is small, fairly simple and looks like it will fix > people's problems. It also makes swappiness=0 behave the way > most people seem to imagine it would work. > > If it works for a few people (test results), I believe we > might as well merge it. > > Yes, for cgroups we may need additional logic, but we can > sort that out as we go along. Now that 3.4 is out with Rik's fixes, I'm keen to start testing with and without this extra patch. Satoru - should I just apply your original patch (most likely), or do you need to update for the final released kernel? Thanks, Richard.