From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f173.google.com (mail-wi0-f173.google.com [209.85.212.173]) by kanga.kvack.org (Postfix) with ESMTP id 2DC926B0035 for ; Fri, 25 Jul 2014 08:34:18 -0400 (EDT) Received: by mail-wi0-f173.google.com with SMTP id f8so915740wiw.0 for ; Fri, 25 Jul 2014 05:34:17 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id cu10si2291187wib.82.2014.07.25.05.34.16 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 25 Jul 2014 05:34:16 -0700 (PDT) Date: Fri, 25 Jul 2014 13:34:13 +0100 From: Mel Gorman Subject: Re: [PATCH V4 09/15] mm, compaction: skip rechecks when lock was already held Message-ID: <20140725123413.GD10819@suse.de> References: <1405518503-27687-1-git-send-email-vbabka@suse.cz> <1405518503-27687-10-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1405518503-27687-10-git-send-email-vbabka@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: linux-mm@kvack.org, Andrew Morton , David Rientjes , linux-kernel@vger.kernel.org, Michal Nazarewicz , Naoya Horiguchi , Christoph Lameter , Rik van Riel , Joonsoo Kim , Minchan Kim , Zhang Yanfei On Wed, Jul 16, 2014 at 03:48:17PM +0200, Vlastimil Babka wrote: > Compaction scanners try to lock zone locks as late as possible by checking > many page or pageblock properties opportunistically without lock and skipping > them if not unsuitable. For pages that pass the initial checks, some properties > have to be checked again safely under lock. However, if the lock was already > held from a previous iteration in the initial checks, the rechecks are > unnecessary. > > This patch therefore skips the rechecks when the lock was already held. This is > now possible to do, since we don't (potentially) drop and reacquire the lock > between the initial checks and the safe rechecks anymore. > > Signed-off-by: Vlastimil Babka > Reviewed-by: Zhang Yanfei > Reviewed-by: Naoya Horiguchi > Acked-by: Minchan Kim > Cc: Mel Gorman > Cc: Michal Nazarewicz > Cc: Naoya Horiguchi > Cc: Christoph Lameter > Cc: Rik van Riel > Acked-by: David Rientjes Acked-by: Mel Gorman -- 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/ . Don't email: email@kvack.org