From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755835Ab1KWNpT (ORCPT ); Wed, 23 Nov 2011 08:45:19 -0500 Received: from cantor2.suse.de ([195.135.220.15]:59619 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755776Ab1KWNpR (ORCPT ); Wed, 23 Nov 2011 08:45:17 -0500 Date: Wed, 23 Nov 2011 13:45:13 +0000 From: Mel Gorman To: Nai Xia Cc: Shaohua Li , Linux-MM , Andrea Arcangeli , Minchan Kim , Jan Kara , Andy Isaacson , Johannes Weiner , Rik van Riel , LKML Subject: Re: [PATCH 7/7] mm: compaction: Introduce sync-light migration for use by compaction Message-ID: <20111123134512.GN19415@suse.de> References: <1321900608-27687-1-git-send-email-mgorman@suse.de> <1321900608-27687-8-git-send-email-mgorman@suse.de> <1321945011.22361.335.camel@sli10-conroe> <20111123110041.GM19415@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 23, 2011 at 09:05:08PM +0800, Nai Xia wrote: > > > > > > Where are you adding this check? > > > > If you mean in __unmap_and_move(), the check is unnecessary unless > > another subsystem starts using sync-light compaction. With this series, > > only direct compaction cares about MIGRATE_SYNC_LIGHT. If the page is > > But I am still a little bit confused that if MIGRATE_SYNC_LIGHT is only > used by direct compaction and another mode can be used by it: > MIGRATE_ASYNC also does not write dirty pages, then why not also > do an (current->flags & PF_MEMALLOC) test before writing out pages, Why would it be necessary? Why would it be better than what is there now? > like we already did for the page lock condition, but adding a new mode > instead? > I'm afraid I am missing the significance of your question or how it might apply to the problem at hand. -- Mel Gorman SUSE Labs