From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f42.google.com (mail-ee0-f42.google.com [74.125.83.42]) by kanga.kvack.org (Postfix) with ESMTP id 17F756B003D for ; Tue, 8 Apr 2014 10:47:43 -0400 (EDT) Received: by mail-ee0-f42.google.com with SMTP id d17so770999eek.15 for ; Tue, 08 Apr 2014 07:47:41 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u5si3065707een.263.2014.04.08.07.47.40 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 08 Apr 2014 07:47:40 -0700 (PDT) Date: Tue, 8 Apr 2014 15:47:35 +0100 From: Mel Gorman Subject: Re: [PATCH 1/2] mm: Disable zone_reclaim_mode by default Message-ID: <20140408144735.GK7292@suse.de> References: <1396910068-11637-1-git-send-email-mgorman@suse.de> <1396910068-11637-2-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: sivanich@sgi.com, Andrew Morton , Robert Haas , Josh Berkus , Andres Freund , Linux-MM , LKML On Tue, Apr 08, 2014 at 09:14:05AM -0500, Christoph Lameter wrote: > On Mon, 7 Apr 2014, Mel Gorman wrote: > > > zone_reclaim_mode causes processes to prefer reclaiming memory from local > > node instead of spilling over to other nodes. This made sense initially when > > NUMA machines were almost exclusively HPC and the workload was partitioned > > into nodes. The NUMA penalties were sufficiently high to justify reclaiming > > the memory. On current machines and workloads it is often the case that > > zone_reclaim_mode destroys performance but not all users know how to detect > > this. Favour the common case and disable it by default. Users that are > > sophisticated enough to know they need zone_reclaim_mode will detect it. > > Ok that is going to require SGI machines to deal with zone_reclaim > configurations on bootup. Dimitri? Any comments? > The SGI machines are also likely to be managed by system administrators who are both aware of zone_reclaim_mode and know how to evaluate if it should be enabled or not. The pair of patches is really aimmed at the common case of 2-8 socket machines running workloads that are not NUMA aware. -- Mel Gorman SUSE Labs -- 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