From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754684Ab1KVRvD (ORCPT ); Tue, 22 Nov 2011 12:51:03 -0500 Received: from mail-vw0-f46.google.com ([209.85.212.46]:53386 "EHLO mail-vw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751472Ab1KVRvB (ORCPT ); Tue, 22 Nov 2011 12:51:01 -0500 Date: Wed, 23 Nov 2011 02:50:55 +0900 From: Minchan Kim To: Mel Gorman Cc: Linux-MM , Andrea Arcangeli , Jan Kara , Andy Isaacson , Johannes Weiner , Rik van Riel , Nai Xia , LKML Subject: Re: [PATCH 6/7] mm: page allocator: Limit when direct reclaim is used when compaction is deferred Message-ID: <20111122175055.GE15253@barrios-laptop.redhat.com> References: <1321900608-27687-1-git-send-email-mgorman@suse.de> <1321900608-27687-7-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1321900608-27687-7-git-send-email-mgorman@suse.de> 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 Mon, Nov 21, 2011 at 06:36:47PM +0000, Mel Gorman wrote: > If compaction is deferred, we enter direct reclaim to try reclaim the > pages that way. For small high-orders, this has a reasonable chance > of success. However, if the caller as specified __GFP_NO_KSWAPD to > limit the disruption to the system, it makes more sense to fail the > allocation rather than stall the caller in direct reclaim. This patch > will skip direct reclaim if compaction is deferred and the caller > specifies __GFP_NO_KSWAPD. > > Async compaction only considers a subset of pages so it is possible for > compaction to be deferred prematurely and not enter direct reclaim even > in cases where it should. To compensate for this, this patch also defers > compaction only if sync compaction failed. > > Signed-off-by: Mel Gorman Acked-by: Minchan Kim It does make sense to me. -- Kind regards, Minchan Kim