From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754285AbbFKOBh (ORCPT ); Thu, 11 Jun 2015 10:01:37 -0400 Received: from casper.infradead.org ([85.118.1.10]:40285 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753228AbbFKOBe (ORCPT ); Thu, 11 Jun 2015 10:01:34 -0400 Date: Thu, 11 Jun 2015 16:01:29 +0200 From: Peter Zijlstra To: Srikar Dronamraju Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Rik van Riel , Mel Gorman Subject: Re: [PATCH] sched:Prefer numa hotness over cache hotness Message-ID: <20150611140129.GV19282@twins.programming.kicks-ass.net> References: <1433919816-20386-1-git-send-email-srikar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1433919816-20386-1-git-send-email-srikar@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 10, 2015 at 12:33:35PM +0530, 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. > Does not apply.