Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752043AbaFWDEB (ORCPT ); Sun, 22 Jun 2014 23:04:01 -0400 Received: from lgeamrelo02.lge.com ([156.147.1.126]:49213 "EHLO lgeamrelo02.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751145AbaFWDEA (ORCPT ); Sun, 22 Jun 2014 23:04:00 -0400 X-Original-SENDERIP: 10.177.220.169 X-Original-MAILFROM: minchan@kernel.org Date: Mon, 23 Jun 2014 12:04:48 +0900 From: Minchan Kim To: Vlastimil Babka Cc: linux-mm@kvack.org, Andrew Morton , David Rientjes , Mel Gorman , Joonsoo Kim , Michal Nazarewicz , Naoya Horiguchi , Christoph Lameter , Rik van Riel , Zhang Yanfei , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 08/13] mm, compaction: remember position within pageblock in free pages scanner Message-ID: <20140623030448.GD12413@bbox> References: <1403279383-5862-1-git-send-email-vbabka@suse.cz> <1403279383-5862-9-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1403279383-5862-9-git-send-email-vbabka@suse.cz> 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 Fri, Jun 20, 2014 at 05:49:38PM +0200, Vlastimil Babka wrote: > Unlike the migration scanner, the free scanner remembers the beginning of the > last scanned pageblock in cc->free_pfn. It might be therefore rescanning pages > uselessly when called several times during single compaction. This might have > been useful when pages were returned to the buddy allocator after a failed > migration, but this is no longer the case. > > This patch changes the meaning of cc->free_pfn so that if it points to a > middle of a pageblock, that pageblock is scanned only from cc->free_pfn to the > end. isolate_freepages_block() will record the pfn of the last page it looked > at, which is then used to update cc->free_pfn. > > In the mmtests stress-highalloc benchmark, this has resulted in lowering the > ratio between pages scanned by both scanners, from 2.5 free pages per migrate > page, to 2.25 free pages per migrate page, without affecting success rates. > > Signed-off-by: Vlastimil Babka > Acked-by: David Rientjes Acked-by: Minchan Kim -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/