From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756693Ab3JGTFQ (ORCPT ); Mon, 7 Oct 2013 15:05:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50141 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756217Ab3JGTFN (ORCPT ); Mon, 7 Oct 2013 15:05:13 -0400 Message-ID: <525305D6.2020205@redhat.com> Date: Mon, 07 Oct 2013 15:04:54 -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 35/63] sched: numa: Do not trap hinting faults for shared libraries References: <1381141781-10992-1-git-send-email-mgorman@suse.de> <1381141781-10992-36-git-send-email-mgorman@suse.de> In-Reply-To: <1381141781-10992-36-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: > NUMA hinting faults will not migrate a shared executable page mapped by > multiple processes on the grounds that the data is probably in the CPU > cache already and the page may just bounce between tasks running on multipl > nodes. Even if the migration is avoided, there is still the overhead of > trapping the fault, updating the statistics, making scheduler placement > decisions based on the information etc. If we are never going to migrate > the page, it is overhead for no gain and worse a process may be placed on > a sub-optimal node for shared executable pages. This patch avoids trapping > faults for shared libraries entirely. > > Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel -- All rights reversed