From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f179.google.com (mail-pd0-f179.google.com [209.85.192.179]) by kanga.kvack.org (Postfix) with ESMTP id 82BC16B012C for ; Tue, 10 Jun 2014 21:50:17 -0400 (EDT) Received: by mail-pd0-f179.google.com with SMTP id fp1so6715159pdb.38 for ; Tue, 10 Jun 2014 18:50:17 -0700 (PDT) Received: from lgeamrelo02.lge.com (lgeamrelo02.lge.com. [156.147.1.126]) by mx.google.com with ESMTP id nu1si36155992pbb.216.2014.06.10.18.50.15 for ; Tue, 10 Jun 2014 18:50:16 -0700 (PDT) Date: Wed, 11 Jun 2014 10:50:20 +0900 From: Minchan Kim Subject: Re: [PATCH 04/10] mm, compaction: skip rechecks when lock was already held Message-ID: <20140611015020.GE15630@bbox> References: <1402305982-6928-1-git-send-email-vbabka@suse.cz> <1402305982-6928-4-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1402305982-6928-4-git-send-email-vbabka@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Greg Thelen , Mel Gorman , Michal Nazarewicz , Naoya Horiguchi , Christoph Lameter , Rik van Riel On Mon, Jun 09, 2014 at 11:26:16AM +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 Acked-by: Minchan Kim -- Kind regards, Minchan Kim -- 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