From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx116.postini.com [74.125.245.116]) by kanga.kvack.org (Postfix) with SMTP id 8B35C6B006C for ; Fri, 16 Nov 2012 10:59:50 -0500 (EST) Received: by mail-ee0-f41.google.com with SMTP id d41so2104387eek.14 for ; Fri, 16 Nov 2012 07:59:48 -0800 (PST) Date: Fri, 16 Nov 2012 16:59:43 +0100 From: Ingo Molnar Subject: Re: [PATCH 0/8] Announcement: Enhanced NUMA scheduling with adaptive affinity Message-ID: <20121116155943.GB4271@gmail.com> References: <20121112160451.189715188@chello.nl> <0000013af701ca15-3acab23b-a16d-4e38-9dc0-efef05cbc5f2-000000@email.amazonses.com> <20121113072441.GA21386@gmail.com> <0000013b04769cf2-b57b16c0-5af0-4e7e-a736-e0aa2d4e4e78-000000@email.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000013b04769cf2-b57b16c0-5af0-4e7e-a736-e0aa2d4e4e78-000000@email.amazonses.com> Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Paul Turner , Lee Schermerhorn , Rik van Riel , Mel Gorman , Andrew Morton , Andrea Arcangeli , Linus Torvalds , Thomas Gleixner * Christoph Lameter wrote: > On Tue, 13 Nov 2012, Ingo Molnar wrote: > > > > the pages over both nodes in use. > > > > I'd not go as far as to claim that to be a general rule: the > > correct placement depends on the system and workload > > specifics: how much memory is on each node, how many tasks > > run on each node, and whether the access patterns and > > working set of the tasks is symmetric amongst each other - > > which is not a given at all. > > > > Say consider a database server that executes small and large > > queries over a large, memory-shared database, and has worker > > tasks to clients, to serve each query. Depending on the > > nature of the queries, interleaving can easily be the wrong > > thing to do. > > The interleaving of memory areas that have an equal amount of > shared accesses from multiple nodes is essential to limit the > traffic on the interconnect and get top performance. That is true only if the load is symmetric. > I guess through that in a non HPC environment where you are > not interested in one specific load running at top speed > varying contention on the interconnect and memory busses are > acceptable. But this means that HPC loads cannot be auto > tuned. I'm not against improving these workloads (at all) - I just pointed out that interleaving isn't necessarily the best placement strategy for 'large' workloads. Thanks, Ingo -- 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