From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f182.google.com (mail-pd0-f182.google.com [209.85.192.182]) by kanga.kvack.org (Postfix) with ESMTP id 54E696B00AE for ; Tue, 8 Apr 2014 10:17:08 -0400 (EDT) Received: by mail-pd0-f182.google.com with SMTP id y10so1068855pdj.27 for ; Tue, 08 Apr 2014 07:17:07 -0700 (PDT) Received: from qmta14.emeryville.ca.mail.comcast.net (qmta14.emeryville.ca.mail.comcast.net. [2001:558:fe2d:44:76:96:27:212]) by mx.google.com with ESMTP id m9si1091628pab.372.2014.04.08.07.17.07 for ; Tue, 08 Apr 2014 07:17:07 -0700 (PDT) Date: Tue, 8 Apr 2014 09:17:04 -0500 (CDT) From: Christoph Lameter 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: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Mel Gorman , Andrew Morton , Robert Haas , Josh Berkus , Andres Freund , Linux-MM , LKML , sivanich@sgi.com 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org