From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f46.google.com (mail-qg0-f46.google.com [209.85.192.46]) by kanga.kvack.org (Postfix) with ESMTP id 6BFE36B0035 for ; Wed, 7 May 2014 10:14:50 -0400 (EDT) Received: by mail-qg0-f46.google.com with SMTP id q108so1093621qgd.5 for ; Wed, 07 May 2014 07:14:50 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id l5si6765226qai.169.2014.05.07.07.14.48 for ; Wed, 07 May 2014 07:14:48 -0700 (PDT) From: Naoya Horiguchi Subject: Re: [patch v3 2/6] mm, compaction: return failed migration target pages back to freelist Date: Wed, 7 May 2014 10:14:37 -0400 Message-Id: <536a3fd8.0542e00a.02f8.66c4SMTPIN_ADDED_BROKEN@mx.google.com> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Andrew Morton , Mel Gorman , Rik van Riel , vbabka@suse.cz, iamjoonsoo.kim@lge.com, gthelen@google.com, Hugh Dickins , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Tue, May 06, 2014 at 07:22:43PM -0700, David Rientjes wrote: > Memory compaction works by having a "freeing scanner" scan from one end of a > zone which isolates pages as migration targets while another "migrating scanner" > scans from the other end of the same zone which isolates pages for migration. > > When page migration fails for an isolated page, the target page is returned to > the system rather than the freelist built by the freeing scanner. This may > require the freeing scanner to continue scanning memory after suitable migration > targets have already been returned to the system needlessly. > > This patch returns destination pages to the freeing scanner freelist when page > migration fails. This prevents unnecessary work done by the freeing scanner but > also encourages memory to be as compacted as possible at the end of the zone. > > Reported-by: Greg Thelen > Acked-by: Mel Gorman > Acked-by: Vlastimil Babka > Signed-off-by: David Rientjes Reviewed-by: Naoya Horiguchi -- 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/ . Don't email: email@kvack.org