Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757100AbaDHORJ (ORCPT ); Tue, 8 Apr 2014 10:17:09 -0400 Received: from qmta15.emeryville.ca.mail.comcast.net ([76.96.27.228]:44057 "EHLO qmta15.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756869AbaDHORH (ORCPT ); Tue, 8 Apr 2014 10:17:07 -0400 Date: Tue, 8 Apr 2014 09:17:04 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@nuc To: Vlastimil Babka cc: Mel Gorman , Andrew Morton , Robert Haas , Josh Berkus , Andres Freund , Linux-MM , LKML , sivanich@sgi.com Subject: Re: [PATCH 0/2] Disable zone_reclaim_mode by default In-Reply-To: <5343A494.9070707@suse.cz> Message-ID: References: <1396910068-11637-1-git-send-email-mgorman@suse.de> <5343A494.9070707@suse.cz> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 8 Apr 2014, Vlastimil Babka wrote: > On 04/08/2014 12:34 AM, Mel Gorman wrote: > > When it was introduced, zone_reclaim_mode made sense as NUMA distances > > punished and workloads were generally partitioned to fit into a NUMA > > node. NUMA machines are now common but few of the workloads are NUMA-aware > > and it's routine to see major performance due to zone_reclaim_mode being > > disabled but relatively few can identify the problem. > ^ I think you meant "enabled" here? > > Just in case the cover letter goes to the changelog... Correct. Another solution here would be to increase the threshhold so that 4 socket machines do not enable zone reclaim by default. The larger the NUMA system is the more memory is off node from the perspective of a processor and the larger the hit from remote memory. On the other hand: The more expensive we make reclaim the less it makes sense to allow zone reclaim to occur. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/