From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 3CAA96B0089 for ; Wed, 23 Nov 2011 09:35:39 -0500 (EST) Received: by vcbfk26 with SMTP id fk26so1839869vcb.14 for ; Wed, 23 Nov 2011 06:35:37 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <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> <20111123134512.GN19415@suse.de> Date: Wed, 23 Nov 2011 22:35:37 +0800 Message-ID: Subject: Re: [PATCH 7/7] mm: compaction: Introduce sync-light migration for use by compaction From: Nai Xia Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Shaohua Li , Linux-MM , Andrea Arcangeli , Minchan Kim , Jan Kara , Andy Isaacson , Johannes Weiner , Rik van Riel , LKML On Wed, Nov 23, 2011 at 9:45 PM, Mel Gorman wrote: > 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 =A0another 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? I mean, if MIGRATE_SYNC_LIGHT --> (current->flags & PF_MEMALLOC), and MIGRATE_SYNC_LIGHT --> no dirty writeback, and (current->flags & PF_MEMALLOC) ---> (MIGRATE_SYNC_LIGHT || MIGRATE_ASYNC) and MIGRATE_ASYNC --> no dirty writeback, then why not simply (current->flags & PF_MEMALLOC) ---> no dirty writeback and keep the sync meaning as it was? Hoping I get myself clear this time...... > >> 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. Sorry, It always takes some effort for me to get myself understood when expressing a complicated thing. That's always my fault ;) Thanks, Nai > > -- > Mel Gorman > SUSE Labs > -- 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