From: Mel Gorman <mgorman@suse.de>
To: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Minchan Kim <minchan.kim@gmail.com>,
Dave Jones <davej@redhat.com>, Jan Kara <jack@suse.cz>,
Andy Isaacson <adi@hexapodia.org>,
Johannes Weiner <jweiner@redhat.com>, Nai Xia <nai.xia@gmail.com>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 10/11] mm: vmscan: Check if reclaim should really abort even if compaction_ready() is true for one zone
Date: Fri, 16 Dec 2011 11:29:54 +0000 [thread overview]
Message-ID: <20111216112954.GG3487@suse.de> (raw)
In-Reply-To: <4EEACB53.4040706@redhat.com>
On Thu, Dec 15, 2011 at 11:38:43PM -0500, Rik van Riel wrote:
> On 12/14/2011 10:41 AM, Mel Gorman wrote:
> >If compaction can proceed for a given zone, shrink_zones() does not
> >reclaim any more pages from it. After commit [e0c2327: vmscan: abort
> >reclaim/compaction if compaction can proceed], do_try_to_free_pages()
> >tries to finish as soon as possible once one zone can compact.
> >
> >This was intended to prevent slabs being shrunk unnecessarily but
> >there are side-effects. One is that a small zone that is ready for
> >compaction will abort reclaim even if the chances of successfully
> >allocating a THP from that zone is small. It also means that reclaim
> >can return too early even though sc->nr_to_reclaim pages were not
> >reclaimed.
>
> Having slabs shrunk "too much" might actually be good,
> because it does result in more memory blocks where
> compaction can be successful.
>
> If we end up frequently evicting frequently accessed
> data from the slab cache, chances are the buffer cache
> will cache that data (since we reload it often).
>
> If we end up evicting infrequently used data, chances
> are it won't really matter for performance.
>
True, but I was being mindful of Dave Chinners recent work on
preventing slab cache being dumped entirely. There still may be an
impact to metadata-intensive workloads although I did not spot any
problems myself.
> >This partially reverts the commit until it is proven that slabs are
> >really being shrunk unnecessarily but preserves the check to return
> >1 to avoid OOM if reclaim was aborted prematurely.
> >
> >[aarcange@redhat.com: This patch replaces a revert from Andrea]
> >Signed-off-by: Mel Gorman<mgorman@suse.de>
>
> Reviewed-by: Rik van Riel<riel@redhat.com>
>
Thanks.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2011-12-16 11:30 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-14 15:41 [PATCH 0/11] Reduce compaction-related stalls and improve asynchronous migration of dirty pages v6 Mel Gorman
2011-12-14 15:41 ` [PATCH 01/11] mm: compaction: Allow compaction to isolate dirty pages Mel Gorman
2011-12-14 15:41 ` [PATCH 02/11] mm: compaction: Use synchronous compaction for /proc/sys/vm/compact_memory Mel Gorman
2011-12-14 15:41 ` [PATCH 03/11] mm: vmscan: Check if we isolated a compound page during lumpy scan Mel Gorman
2011-12-15 23:21 ` Rik van Riel
2011-12-14 15:41 ` [PATCH 04/11] mm: vmscan: Do not OOM if aborting reclaim to start compaction Mel Gorman
2011-12-15 23:36 ` Rik van Riel
2011-12-14 15:41 ` [PATCH 05/11] mm: compaction: Determine if dirty pages can be migrated without blocking within ->migratepage Mel Gorman
2011-12-16 3:32 ` Rik van Riel
2011-12-16 23:20 ` Andrew Morton
2011-12-17 3:03 ` Nai Xia
2011-12-17 3:26 ` Andrew Morton
2011-12-19 11:05 ` Mel Gorman
2011-12-19 13:12 ` nai.xia
2011-12-14 15:41 ` [PATCH 06/11] mm: compaction: make isolate_lru_page() filter-aware again Mel Gorman
2011-12-16 3:34 ` Rik van Riel
2011-12-18 1:53 ` Minchan Kim
2011-12-14 15:41 ` [PATCH 07/11] mm: page allocator: Do not call direct reclaim for THP allocations while compaction is deferred Mel Gorman
2011-12-16 4:10 ` Rik van Riel
2011-12-14 15:41 ` [PATCH 08/11] mm: compaction: Introduce sync-light migration for use by compaction Mel Gorman
2011-12-16 4:31 ` Rik van Riel
2011-12-18 2:05 ` Minchan Kim
2011-12-19 11:45 ` Mel Gorman
2011-12-20 7:18 ` Minchan Kim
2012-01-13 21:25 ` Andrew Morton
2012-01-16 11:33 ` Mel Gorman
2011-12-14 15:41 ` [PATCH 09/11] mm: vmscan: When reclaiming for compaction, ensure there are sufficient free pages available Mel Gorman
2011-12-16 4:35 ` Rik van Riel
2011-12-14 15:41 ` [PATCH 10/11] mm: vmscan: Check if reclaim should really abort even if compaction_ready() is true for one zone Mel Gorman
2011-12-16 4:38 ` Rik van Riel
2011-12-16 11:29 ` Mel Gorman [this message]
2011-12-14 15:41 ` [PATCH 11/11] mm: Isolate pages for immediate reclaim on their own LRU Mel Gorman
2011-12-16 4:47 ` Rik van Riel
2011-12-16 12:26 ` Mel Gorman
2011-12-16 15:17 ` Johannes Weiner
2011-12-16 16:07 ` Mel Gorman
2011-12-19 16:14 ` Johannes Weiner
2011-12-17 16:08 ` Minchan Kim
2011-12-19 13:26 ` Mel Gorman
2011-12-20 7:10 ` Minchan Kim
2011-12-20 9:55 ` Mel Gorman
2011-12-23 19:08 ` Hugh Dickins
2011-12-29 16:59 ` Mel Gorman
2011-12-29 19:31 ` Rik van Riel
2011-12-30 11:27 ` Mel Gorman
2011-12-16 22:56 ` [PATCH 0/11] Reduce compaction-related stalls and improve asynchronous migration of dirty pages v6 Andrew Morton
2011-12-19 14:40 ` Mel Gorman
2011-12-16 23:37 ` Andrew Morton
2011-12-19 14:20 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2011-12-01 17:36 [PATCH 0/11] Reduce compaction-related stalls and improve asynchronous migration of dirty pages v5 Mel Gorman
2011-12-01 17:36 ` [PATCH 10/11] mm: vmscan: Check if reclaim should really abort even if compaction_ready() is true for one zone Mel Gorman
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