From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id B590090010D for ; Mon, 16 May 2011 17:04:07 -0400 (EDT) Received: from hpaq5.eem.corp.google.com (hpaq5.eem.corp.google.com [172.25.149.5]) by smtp-out.google.com with ESMTP id p4GL3ojZ029652 for ; Mon, 16 May 2011 14:03:50 -0700 Received: from pzk1 (pzk1.prod.google.com [10.243.19.129]) by hpaq5.eem.corp.google.com with ESMTP id p4GL3TnO030208 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Mon, 16 May 2011 14:03:43 -0700 Received: by pzk1 with SMTP id 1so3158958pzk.16 for ; Mon, 16 May 2011 14:03:35 -0700 (PDT) Date: Mon, 16 May 2011 14:03:33 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH 3/3] mm: slub: Default slub_max_order to 0 In-Reply-To: <20110512173628.GJ11579@random.random> Message-ID: References: <1305127773-10570-1-git-send-email-mgorman@suse.de> <1305127773-10570-4-git-send-email-mgorman@suse.de> <20110512173628.GJ11579@random.random> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: Mel Gorman , Andrew Morton , James Bottomley , Colin King , Raghavendra D Prabhu , Jan Kara , Chris Mason , Christoph Lameter , Pekka Enberg , Rik van Riel , Johannes Weiner , linux-fsdevel , linux-mm , linux-kernel , linux-ext4 On Thu, 12 May 2011, Andrea Arcangeli wrote: > On Wed, May 11, 2011 at 01:38:47PM -0700, David Rientjes wrote: > > kswapd and doing compaction for the higher order allocs before falling > > Note that patch 2 disabled compaction by clearing __GFP_WAIT. > > What you describe here would be patch 2 without the ~__GFP_WAIT > addition (so keeping only ~GFP_NOFAIL). > It's out of context, my sentence was: "With the previous changes in this patchset, specifically avoiding waking kswapd and doing compaction for the higher order allocs before falling back to the min order..." meaning this patchset avoids waking kswapd and avoids doing compaction. > Not clearing __GFP_WAIT when compaction is enabled is possible and > shouldn't result in bad behavior (if compaction is not enabled with > current SLUB it's hard to imagine how it could perform decently if > there's fragmentation). You should try to benchmark to see if it's > worth it on the large NUMA systems with heavy network traffic (for > normal systems I doubt compaction is worth it but I'm not against > trying to keep it enabled just in case). > The fragmentation isn't the only issue with the netperf TCP_RR benchmark, the problem is that the slub slowpath is being used >95% of the time on every allocation and free for the very large number of kmalloc-256 and kmalloc-2K caches. Those caches are order 1 and 3, respectively, on my system by default, but the page allocator seldomly gets invoked for such a benchmark after the partial lists are populated: the overhead is from the per-node locking required in the slowpath to traverse the partial lists. See the data I presented two years ago: http://lkml.org/lkml/2009/3/30/15. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org