From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756741Ab3JGTKZ (ORCPT ); Mon, 7 Oct 2013 15:10:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56846 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751475Ab3JGTKW (ORCPT ); Mon, 7 Oct 2013 15:10:22 -0400 Message-ID: <525306DE.4090102@redhat.com> Date: Mon, 07 Oct 2013 15:09:18 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Mel Gorman CC: Peter Zijlstra , Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML Subject: Re: [PATCH 43/63] sched: numa: Use {cpu, pid} to create task groups for shared faults References: <1381141781-10992-1-git-send-email-mgorman@suse.de> <1381141781-10992-44-git-send-email-mgorman@suse.de> In-Reply-To: <1381141781-10992-44-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/07/2013 06:29 AM, Mel Gorman wrote: > From: Peter Zijlstra > > While parallel applications tend to align their data on the cache > boundary, they tend not to align on the page or THP boundary. > Consequently tasks that partition their data can still "false-share" > pages presenting a problem for optimal NUMA placement. > > This patch uses NUMA hinting faults to chain tasks together into > numa_groups. As well as storing the NID a task was running on when > accessing a page a truncated representation of the faulting PID is > stored. If subsequent faults are from different PIDs it is reasonable > to assume that those two tasks share a page and are candidates for > being grouped together. Note that this patch makes no scheduling > decisions based on the grouping information. > > Signed-off-by: Peter Zijlstra > Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel -- All rights reversed