From: Christoph Lameter Subject: Re: [PATCH 3/4] mm: slub: Do not take expensive steps for SLUBs speculative high-order allocations Date: Tue, 17 May 2011 08:51:47 -0500 (CDT) Message-ID: References: <1305295404-12129-1-git-send-email-mgorman@suse.de> <1305295404-12129-4-git-send-email-mgorman@suse.de> <20110517084227.GI5279@suse.de> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: David Rientjes , Andrew Morton , James Bottomley , Colin King , Raghavendra D Prabhu , Jan Kara , Chris Mason , Pekka Enberg , Rik van Riel , Johannes Weiner , linux-fsdevel , linux-mm , linux-kernel , linux-ext4 To: Mel Gorman Return-path: Received: from smtp107.prem.mail.ac4.yahoo.com ([76.13.13.46]:40887 "HELO smtp107.prem.mail.ac4.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754567Ab1EQNvw (ORCPT ); Tue, 17 May 2011 09:51:52 -0400 In-Reply-To: <20110517084227.GI5279@suse.de> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, 17 May 2011, Mel Gorman wrote: > entirely. Christoph wants to maintain historic behaviour of SLUB to > maximise the number of high-order pages it uses and at the end of the > day, which option performs better depends entirely on the workload > and machine configuration. That is not what I meant. I would like more higher order allocations to succeed. That does not mean that slubs allocation methods and flags passed have to stay the same. You can change the slub behavior if it helps. I am just suspicious of compaction. If these mods are needed to reduce the amount of higher order pages then compaction does not have the beneficial effect that it should have. It does not actually increase the available higher order pages. Fix that first.