From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754680AbYE2Msv (ORCPT ); Thu, 29 May 2008 08:48:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752049AbYE2Msm (ORCPT ); Thu, 29 May 2008 08:48:42 -0400 Received: from mtagate6.de.ibm.com ([195.212.29.155]:51979 "EHLO mtagate6.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751706AbYE2Msm (ORCPT ); Thu, 29 May 2008 08:48:42 -0400 Message-ID: <483EA5EF.70906@de.ibm.com> Date: Thu, 29 May 2008 14:47:43 +0200 From: Carsten Otte Reply-To: carsteno@de.ibm.com Organization: =?ISO-8859-1?Q?IBM_Deutschland_Entwicklung_GmbH=2CVor?= =?ISO-8859-1?Q?sitzender_des_Aufsichtsrats=3A_Martin_Jetter=2CGe?= =?ISO-8859-1?Q?sch=E4ftsf=FChrung=3A_Herbert_Kircher=2CSitz_der_?= =?ISO-8859-1?Q?Gesellschaft=3A_B=F6blingen=2CRegistergericht=3A_Amts?= =?ISO-8859-1?Q?gericht_Stuttgart=2C_HRB_243294?= User-Agent: Mozilla-Thunderbird 2.0.0.14 (X11/20080509) MIME-Version: 1.0 To: Rik van Riel CC: linux-kernel@vger.kernel.org, Christian Borntraeger Subject: Re: [PATCH -mm 00/16] VM pageout scalability improvements (V8) References: <20080523195506.084894989@redhat.com> In-Reply-To: <20080523195506.084894989@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rik van Riel wrote: > On large memory systems, the VM can spend way too much time scanning > through pages that it cannot (or should not) evict from memory. Not > only does it use up CPU time, but it also provokes lock contention > and can leave large systems under memory presure in a catatonic state. > > Against 2.6.26-rc2-mm1 > > This patch series improves VM scalability by: > > 1) putting filesystem backed, swap backed and non-reclaimable pages > onto their own LRUs, so the system only scans the pages that it > can/should evict from memory > > 2) switching to SEQ replacement for the anonymous LRUs, so the > number of pages that need to be scanned when the system > starts swapping is bound to a reasonable number > > 3) keeping non-reclaimable pages off the LRU completely, so the > VM does not waste CPU time scanning them. Currently only > ramfs and SHM_LOCKED pages are kept on the noreclaim list, > mlock()ed VMAs will be added later I think I've run into #2 with kvm on s390 lately. I've tried a large setup with 200 guests running WebSphere. The guest memory is stored in anonymous pages, all guests are started up from a script so everything is dirty initially. I use 200gig swap with 45 gig main memory for the scenario. Everything runs perfect except when vmscan is triggered for the first time: it starts to writeback, and the whole system freezes until it has paged out the 15gig in the inactive list. From there on, everything runs smooth again with a constant swap rate. I'd like to try your patchset to see how that behave in this scenario. Do you have a version that applies against current git, 2.6.26-rc3 or similar?