From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755775Ab2GaV41 (ORCPT ); Tue, 31 Jul 2012 17:56:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:9564 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753640Ab2GaV4Y (ORCPT ); Tue, 31 Jul 2012 17:56:24 -0400 Message-ID: <5018547B.4020000@redhat.com> Date: Tue, 31 Jul 2012 17:56:11 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Peter Zijlstra CC: mingo@kernel.org, oleg@redhat.com, pjt@google.com, akpm@linux-foundation.org, torvalds@linux-foundation.org, tglx@linutronix.de, Lee.Schermerhorn@hp.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 18/19] sched, numa: Per task memory placement for big processes References: <20120731191204.540691987@chello.nl> <20120731192809.428855038@chello.nl> In-Reply-To: <20120731192809.428855038@chello.nl> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/31/2012 03:12 PM, Peter Zijlstra wrote: > Probability says that the task faulting on a page after we protect it, > is most likely to be the task that uses that page most. > > To decrease the likelyhood of acting on a false relation, we only > migrate a page when two consecutive samples are from the same task. > > I'm still not entirely convinced this scheme is sound, esp. for things > like virtualization and n:m threading solutions in general the > compute<->task relation is fundamentally untrue. Again, we may need some additional code on top in the future, eg. something like Andrea's policy that tries grouping related tasks/threads together, but this looks like a very good way to start. We can introduce complexity if it is needed. Simplicity is good. Acked-by: Rik van Riel -- All rights reversed