From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754833AbaA1J6e (ORCPT ); Tue, 28 Jan 2014 04:58:34 -0500 Received: from cantor2.suse.de ([195.135.220.15]:54545 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751711AbaA1J6c (ORCPT ); Tue, 28 Jan 2014 04:58:32 -0500 Date: Tue, 28 Jan 2014 09:58:28 +0000 From: Mel Gorman To: riel@redhat.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, peterz@infradead.org, mingo@redhat.com, chegu_vinod@hp.com Subject: Re: [PATCH 5/9] numa,sched,mm: use active_nodes nodemask to limit numa migrations Message-ID: <20140128095828.GR4963@suse.de> References: <1390860228-21539-1-git-send-email-riel@redhat.com> <1390860228-21539-6-git-send-email-riel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1390860228-21539-6-git-send-email-riel@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 27, 2014 at 05:03:44PM -0500, riel@redhat.com wrote: > From: Rik van Riel > > Use the active_nodes nodemask to make smarter decisions on NUMA migrations. > > In order to maximize performance of workloads that do not fit in one NUMA > node, we want to satisfy the following criteria: > 1) keep private memory local to each thread > 2) avoid excessive NUMA migration of pages > 3) distribute shared memory across the active nodes, to > maximize memory bandwidth available to the workload > > This patch accomplishes that by implementing the following policy for > NUMA migrations: > 1) always migrate on a private fault > 2) never migrate to a node that is not in the set of active nodes > for the numa_group > 3) always migrate from a node outside of the set of active nodes, > to a node that is in that set > 4) within the set of active nodes in the numa_group, only migrate > from a node with more NUMA page faults, to a node with fewer > NUMA page faults, with a 25% margin to avoid ping-ponging > > This results in most pages of a workload ending up on the actively > used nodes, with reduced ping-ponging of pages between those nodes. > > Cc: Peter Zijlstra > Cc: Mel Gorman > Cc: Ingo Molnar > Cc: Chegu Vinod > Signed-off-by: Rik van Riel Acked-by: Mel Gorman -- Mel Gorman SUSE Labs