From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <45E89F1E.8020803@redhat.com> Date: Fri, 02 Mar 2007 17:03:10 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: The performance and behaviour of the anti-fragmentation related patches References: <20070301101249.GA29351@skynet.ie> <20070301160915.6da876c5.akpm@linux-foundation.org> <45E842F6.5010105@redhat.com> <20070302085838.bcf9099e.akpm@linux-foundation.org> <20070302093501.34c6ef2a.akpm@linux-foundation.org> <45E8624E.2080001@redhat.com> <20070302100619.cec06d6a.akpm@linux-foundation.org> <45E86BA0.50508@redhat.com> <20070302211207.GJ10643@holomorphy.com> <45E894D7.2040309@redhat.com> <20070302135243.ada51084.akpm@linux-foundation.org> In-Reply-To: <20070302135243.ada51084.akpm@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Bill Irwin , Christoph Lameter , Mel Gorman , npiggin@suse.de, mingo@elte.hu, jschopp@austin.ibm.com, arjan@infradead.org, torvalds@linux-foundation.org, mbligh@mbligh.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: Andrew Morton wrote: > On Fri, 02 Mar 2007 16:19:19 -0500 > Rik van Riel wrote: >> Bill Irwin wrote: >>> On Fri, Mar 02, 2007 at 01:23:28PM -0500, Rik van Riel wrote: >>>> With 32 CPUs diving into the page reclaim simultaneously, >>>> each trying to scan a fraction of memory, this is disastrous >>>> for performance. A 256GB system should be even worse. >>> Thundering herds of a sort pounding the LRU locks from direct reclaim >>> have set off the NMI oopser for users here. >> Ditto here. > > Opterons? It's happened on IA64, too. Probably on Intel x86-64 as well. >> The main reason they end up pounding the LRU locks is the >> swappiness heuristic. They scan too much before deciding >> that it would be a good idea to actually swap something >> out, and with 32 CPUs doing such scanning simultaneously... > > What kernel version? Customers are on the 2.6.9 based RHEL4 kernel, but I believe we have reproduced the problem on 2.6.18 too during stress tests. I have no reason to believe we should stick our heads in the sand and pretend it no longer exists on 2.6.21. -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. -- 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