From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760043Ab1LPDdZ (ORCPT ); Thu, 15 Dec 2011 22:33:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1027 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751772Ab1LPDdY (ORCPT ); Thu, 15 Dec 2011 22:33:24 -0500 Message-ID: <4EEABBE3.1050309@redhat.com> Date: Thu, 15 Dec 2011 22:32:51 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0 MIME-Version: 1.0 To: Mel Gorman CC: Andrew Morton , Andrea Arcangeli , Minchan Kim , Dave Jones , Jan Kara , Andy Isaacson , Johannes Weiner , Nai Xia , Linux-MM , LKML Subject: Re: [PATCH 05/11] mm: compaction: Determine if dirty pages can be migrated without blocking within ->migratepage References: <1323877293-15401-1-git-send-email-mgorman@suse.de> <1323877293-15401-6-git-send-email-mgorman@suse.de> In-Reply-To: <1323877293-15401-6-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/14/2011 10:41 AM, Mel Gorman wrote: > Asynchronous compaction is used when allocating transparent hugepages > to avoid blocking for long periods of time. Due to reports of > stalling, there was a debate on disabling synchronous compaction > but this severely impacted allocation success rates. Part of the > reason was that many dirty pages are skipped in asynchronous compaction > by the following check; > > if (PageDirty(page)&& !sync&& > mapping->a_ops->migratepage != migrate_page) > rc = -EBUSY; > > This skips over all mapping aops using buffer_migrate_page() > even though it is possible to migrate some of these pages without > blocking. This patch updates the ->migratepage callback with a "sync" > parameter. It is the responsibility of the callback to fail gracefully > if migration would block. > > Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel -- All rights reversed