From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965081AbbFJONF (ORCPT ); Wed, 10 Jun 2015 10:13:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56715 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964809AbbFJOMn (ORCPT ); Wed, 10 Jun 2015 10:12:43 -0400 Message-ID: <557845D5.6060800@redhat.com> Date: Wed, 10 Jun 2015 10:12:37 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Srikar Dronamraju , Ingo Molnar , Peter Zijlstra CC: linux-kernel@vger.kernel.org, Mel Gorman Subject: Re: [PATCH] sched:Prefer numa hotness over cache hotness References: <1433919816-20386-1-git-send-email-srikar@linux.vnet.ibm.com> In-Reply-To: <1433919816-20386-1-git-send-email-srikar@linux.vnet.ibm.com> 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 06/10/2015 03:03 AM, Srikar Dronamraju wrote: > The current load balancer may not try to prevent a task from moving out > of a preferred node to a less preferred node. The reason for this being: > > - Since sched features NUMA and NUMA_RESIST_LOWER are disabled by > default, migrate_degrades_locality() always returns false. > > - Even if NUMA_RESIST_LOWER were to be enabled, if its cache hot, > migrate_degrades_locality() never gets called. > > The above behaviour can mean that tasks can move out of their preferred > node but they may be eventually be brought back to their preferred node > by numa balancer (due to higher numa faults). > > To avoid the above, this commit merges migrate_degrades_locality() and > migrate_improves_locality(). It also replaces 3 sched features NUMA, > NUMA_FAVOUR_HIGHER and NUMA_RESIST_LOWER by a single sched feature NUMA. I had been looking at merging the two at well, but ran into a dead end because I failed to reorder NUMA and cache_hot testing. Nice work. > Signed-off-by: Srikar Dronamraju Acked-by: Rik van Riel -- All rights reversed