From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx120.postini.com [74.125.245.120]) by kanga.kvack.org (Postfix) with SMTP id AE03E6B0044 for ; Thu, 26 Apr 2012 14:52:53 -0400 (EDT) Message-ID: <4F999988.802@redhat.com> Date: Thu, 26 Apr 2012 14:52:56 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH v3] mm: compaction: handle incorrect Unmovable type pageblocks References: <201204261015.54449.b.zolnierkie@samsung.com> <20120426143620.GF15299@suse.de> <4F996F8B.1020207@redhat.com> <20120426164713.GG15299@suse.de> In-Reply-To: <20120426164713.GG15299@suse.de> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Bartlomiej Zolnierkiewicz , linux-mm@kvack.org, Minchan Kim , Marek Szyprowski , Kyungmin Park On 04/26/2012 12:47 PM, Mel Gorman wrote: > Instead of COMPACT_ASYNC_PARTIAL and COMPACT_ASYNC_FULL should we have > COMPACT_ASYNC_MOVABLE and COMPACT_ASYNC_UNMOVABLE? The first pass from > the page allocator (COMPACT_ASYNC_MOVABLE) would only consider MOVABLE > blocks as migration targets. The second pass (COMPACT_ASYNC_UNMOVABLE) > would examine UNMOVABLE blocks, rescue them and use what blocks it > rescues as migration targets. The third pass (COMPACT_SYNC) would work > as it does currently. kswapd would only ever use COMPACT_ASYNC_MOVABLE. > > That would avoid rescanning the movable blocks uselessly on the second > pass but should still work for Bartlomiej's workload. > > What do you think? This makes sense. >> In other words, could it be better to always try to >> rescue the unmovable blocks? > > I do not think we should always scan within unmovable blocks on the > first pass. I strongly suspect it would lead to excessive amounts of CPU > time spent in mm/compaction.c. Maybe my systems are not typical. I have not seen more than about 10% of the memory blocks marked as unmovable in my system. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org