From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754024AbYE1LvQ (ORCPT ); Wed, 28 May 2008 07:51:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752592AbYE1LvF (ORCPT ); Wed, 28 May 2008 07:51:05 -0400 Received: from E23SMTP02.au.ibm.com ([202.81.18.163]:59485 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752380AbYE1Lup (ORCPT ); Wed, 28 May 2008 07:50:45 -0400 Message-ID: <483D46CE.2020507@linux.vnet.ibm.com> Date: Wed, 28 May 2008 17:19:34 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com Organization: IBM User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Rik van Riel CC: linux-kernel@vger.kernel.org, Andrew Morton , Lee Schermerhorn , Kosaki Motohiro Subject: Re: [PATCH -mm 00/16] VM pageout scalability improvements (V8) References: <20080523195506.084894989@redhat.com> <483B0077.7000207@linux.vnet.ibm.com> <20080526153318.29edc0b2@bree.surriel.com> In-Reply-To: <20080526153318.29edc0b2@bree.surriel.com> Content-Type: text/plain; charset=ISO-8859-1 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 Mon, 26 May 2008 23:54:55 +0530 > Balbir Singh wrote: > >> 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. >> Hi, Rik, >> >> This patchset looks good (I did a brief scan). I'll go ahead and play with it? >> What is a good memory size to test the patches on (to see improvements). > > The larger, the better. One known problem with the current upstream > VM is large numbers of anonymous pages, or a mix of mlocked and anon > pages. > > Once the system needs to swap something out, every single anon page > will have the referenced bit set and the system needs to do lots of > scanning before it can evict the first page. This scanning causes > multiple CPUs to pile up and things slow down exponentially and/or > catastrophically :) > > Unfortunately the largest system I have access to on a regular basis > has "only" 16GB of RAM :( > > I am also making 2.6.25 based kernel RPMs available with the split LRU > patch set, at http://people.redhat.com/riel/splitvm/ > > The most recently posted patches are newer, though... > Rik, I've run into a case where with the splitvm patches the memory controller immediately OOMs a task in the cgroup on exceeding it's limit. I am going to try and find the root cause for it. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL