From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f181.google.com (mail-qc0-f181.google.com [209.85.216.181]) by kanga.kvack.org (Postfix) with ESMTP id 9FF6D6B0032 for ; Sat, 31 Jan 2015 05:18:11 -0500 (EST) Received: by mail-qc0-f181.google.com with SMTP id l6so24113053qcy.12 for ; Sat, 31 Jan 2015 02:18:11 -0800 (PST) Received: from BLU004-OMC2S33.hotmail.com (blu004-omc2s33.hotmail.com. [65.55.111.108]) by mx.google.com with ESMTPS id r2si16735940qcq.9.2015.01.31.02.18.10 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sat, 31 Jan 2015 02:18:10 -0800 (PST) Message-ID: Date: Sat, 31 Jan 2015 18:17:55 +0800 From: Zhang Yanfei MIME-Version: 1.0 Subject: Re: [PATCH v2 2/4] mm/compaction: stop the isolation when we isolate enough freepage References: <1422621252-29859-1-git-send-email-iamjoonsoo.kim@lge.com> <1422621252-29859-3-git-send-email-iamjoonsoo.kim@lge.com> <54CC92FD.5000601@suse.cz> In-Reply-To: <54CC92FD.5000601@suse.cz> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka , Joonsoo Kim , Andrew Morton Cc: Mel Gorman , David Rientjes , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim At 2015/1/31 16:31, Vlastimil Babka wrote: > On 01/31/2015 08:49 AM, Zhang Yanfei wrote: >> Hello, >> >> At 2015/1/30 20:34, Joonsoo Kim wrote: >> >> Reviewed-by: Zhang Yanfei >> >> IMHO, the patch making the free scanner move slower makes both scanners >> meet further. Before this patch, if we isolate too many free pages and even >> after we release the unneeded free pages later the free scanner still already >> be there and will be moved forward again next time -- the free scanner just >> cannot be moved back to grab the free pages we released before no matter where >> the free pages in, pcp or buddy. > > It can be actually moved back. If we are releasing free pages, it means the > current compaction is terminating, and it will set zone->compact_cached_free_pfn > back to the position of the released free page that was furthest back. The next > compaction will start from the cached free pfn. Yeah, you are right. I missed the release_freepages(). Thanks! > > It is however possible that another compaction runs in parallel and has > progressed further and overwrites the cached free pfn. > Hmm, maybe. Thanks. -- 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