From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f54.google.com (mail-ee0-f54.google.com [74.125.83.54]) by kanga.kvack.org (Postfix) with ESMTP id 7AF2C6B003D for ; Tue, 8 Apr 2014 10:26:53 -0400 (EDT) Received: by mail-ee0-f54.google.com with SMTP id d49so773034eek.27 for ; Tue, 08 Apr 2014 07:26:51 -0700 (PDT) Received: from moutng.kundenserver.de (moutng.kundenserver.de. [212.227.17.10]) by mx.google.com with ESMTPS id 43si2981755eei.325.2014.04.08.07.26.50 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 08 Apr 2014 07:26:50 -0700 (PDT) Date: Tue, 8 Apr 2014 16:26:42 +0200 From: Andres Freund Subject: Re: [PATCH 0/2] Disable zone_reclaim_mode by default Message-ID: <20140408142642.GU4161@awork2.anarazel.de> References: <1396910068-11637-1-git-send-email-mgorman@suse.de> <5343A494.9070707@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Vlastimil Babka , Mel Gorman , Andrew Morton , Robert Haas , Josh Berkus , Linux-MM , LKML , sivanich@sgi.com On 2014-04-08 09:17:04 -0500, Christoph Lameter wrote: > 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. FWIW, I've the problem hit majorly on 8 socket machines. Those are the largest I have seen so far in postgres scenarios. Everything larger is far less likely to be used as single node database server, so that's possibly a sensible cutoff. But then, I'd think that special many-socket machines are setup by specialists, that'd know to enable if it makes sense... Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- 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