From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx138.postini.com [74.125.245.138]) by kanga.kvack.org (Postfix) with SMTP id 225AC6B005C for ; Fri, 15 Jun 2012 03:32:43 -0400 (EDT) Message-ID: <4FDAE521.7020104@kernel.org> Date: Fri, 15 Jun 2012 16:32:49 +0900 From: Minchan Kim MIME-Version: 1.0 Subject: Re: [PATCH v11 1/2] mm: compaction: handle incorrect MIGRATE_UNMOVABLE type pageblocks References: <201206141800.31038.b.zolnierkie@samsung.com> In-Reply-To: <201206141800.31038.b.zolnierkie@samsung.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Bartlomiej Zolnierkiewicz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Hugh Dickins , KOSAKI Motohiro , Dave Jones , Cong Wang , Markus Trippelsdorf , Mel Gorman , Rik van Riel , Marek Szyprowski , Kyungmin Park On 06/15/2012 01:00 AM, Bartlomiej Zolnierkiewicz wrote: > > Hi, > > Most important changes from v10: > > * port patch over > https://lkml.org/lkml/2012/6/13/568 > https://lkml.org/lkml/2012/6/13/570 > patches from Minchan Kim > > * split new /proc/vmstat entry addition to separate patch (#2/2) > > Best regards, > -- > Bartlomiej Zolnierkiewicz > Samsung Poland R&D Center > > > From: Bartlomiej Zolnierkiewicz > Subject: [PATCH v11] mm: compaction: handle incorrect MIGRATE_UNMOVABLE type pageblocks > > When MIGRATE_UNMOVABLE pages are freed from MIGRATE_UNMOVABLE > type pageblock (and some MIGRATE_MOVABLE pages are left in it) > waiting until an allocation takes ownership of the block may > take too long. The type of the pageblock remains unchanged > so the pageblock cannot be used as a migration target during > compaction. > > Fix it by: > > * Adding enum compact_mode (COMPACT_ASYNC_[MOVABLE,UNMOVABLE], > and COMPACT_SYNC) and then converting sync field in struct > compact_control to use it. > > * Adding nr_pageblocks_skipped field to struct compact_control > and tracking how many destination pageblocks were of > MIGRATE_UNMOVABLE type. If COMPACT_ASYNC_MOVABLE mode compaction > ran fully in try_to_compact_pages() (COMPACT_COMPLETE) it implies > that there is not a suitable page for allocation. In this case > then check how if there were enough MIGRATE_UNMOVABLE pageblocks > to try a second pass in COMPACT_ASYNC_UNMOVABLE mode. > > * Scanning the MIGRATE_UNMOVABLE pageblocks (during COMPACT_SYNC > and COMPACT_ASYNC_UNMOVABLE compaction modes) and building > a count based on finding PageBuddy pages, page_count(page) == 0 > or PageLRU pages. If all pages within the MIGRATE_UNMOVABLE > pageblock are in one of those three sets change the whole > pageblock type to MIGRATE_MOVABLE. > > My particular test case (on a ARM EXYNOS4 device with 512 MiB, > which means 131072 standard 4KiB pages in 'Normal' zone) is to: > - allocate 95000 pages for kernel's usage > - free every second page (47500 pages) of memory just allocated > - allocate and use 60000 pages from user space > - free remaining 60000 pages of kernel memory > (now we have fragmented memory occupied mostly by user space pages) > - try to allocate 100 order-9 (2048 KiB) pages for kernel's usage > > The results: > - with compaction disabled I get 10 successful allocations > - with compaction enabled - 11 successful allocations > - with this patch I'm able to get 25 successful allocations > > NOTE: If we can make kswapd aware of order-0 request during > compaction, we can enhance kswapd with changing mode to > COMPACT_ASYNC_FULL (COMPACT_ASYNC_MOVABLE + COMPACT_ASYNC_UNMOVABLE). > Please see the following thread: > > http://marc.info/?l=linux-mm&m=133552069417068&w=2 > > [minchan@kernel.org: minor cleanups] > Cc: Hugh Dickins > Cc: KOSAKI Motohiro > Cc: Dave Jones > Cc: Cong Wang > Cc: Markus Trippelsdorf > Cc: Mel Gorman > Cc: Minchan Kim > Cc: Rik van Riel > Cc: Marek Szyprowski > Signed-off-by: Bartlomiej Zolnierkiewicz > Signed-off-by: Kyungmin Park Reviewed-by: Minchan Kim Thanks, Bartlomiej! -- 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