Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753795AbYJAPCp (ORCPT ); Wed, 1 Oct 2008 11:02:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752453AbYJAPCh (ORCPT ); Wed, 1 Oct 2008 11:02:37 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:45002 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752400AbYJAPCg (ORCPT ); Wed, 1 Oct 2008 11:02:36 -0400 Message-ID: <48E390DA.9060109@linux-foundation.org> Date: Wed, 01 Oct 2008 10:01:46 -0500 From: Christoph Lameter User-Agent: Thunderbird 2.0.0.17 (Windows/20080914) MIME-Version: 1.0 To: Andy Whitcroft CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org, KOSAKI Motohiro , Peter Zijlstra , Rik van Riel , Mel Gorman , Nick Piggin , Andrew Morton Subject: Re: [PATCH 4/4] capture pages freed during direct reclaim for allocation by the reclaimer References: <1222864261-22570-1-git-send-email-apw@shadowen.org> <1222864261-22570-5-git-send-email-apw@shadowen.org> In-Reply-To: <1222864261-22570-5-git-send-email-apw@shadowen.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1189 Lines: 22 Andy Whitcroft wrote: > When a process enters direct reclaim it will expend effort identifying > and releasing pages in the hope of obtaining a page. However as these > pages are released asynchronously there is every possibility that the > pages will have been consumed by other allocators before the reclaimer > gets a look in. This is particularly problematic where the reclaimer is > attempting to allocate a higher order page. It is highly likely that > a parallel allocation will consume lower order constituent pages as we > release them preventing them coelescing into the higher order page the > reclaimer desires. The reclaim problem is due to the pcp queueing right? Could we disable pcp queueing during reclaim? pcp processing is not necessarily a gain, so temporarily disabling it should not be a problem. At the beginning of reclaim just flush all pcp pages and then do not allow pcp refills again until reclaim is finished? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/