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 6E2D56B004D for ; Mon, 7 May 2012 20:05:09 -0400 (EDT) Message-ID: <4FA86332.6080601@kernel.org> Date: Tue, 08 May 2012 09:05:06 +0900 From: Minchan Kim MIME-Version: 1.0 Subject: Re: [RFC][PATCH] avoid swapping out with swappiness==0 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> In-Reply-To: <4FA82C11.2030805@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: KOSAKI Motohiro , Richard Davies , 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 On 05/08/2012 05:09 AM, Rik van Riel wrote: > On 04/26/2012 11:41 AM, KOSAKI Motohiro wrote: >> On Thu, Apr 26, 2012 at 10:26 AM, 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. > I agree Rik's opinion absolutely. -- Kind regards, Minchan Kim -- 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