From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>, Linux-MM <linux-mm@kvack.org>
Cc: David Rientjes <rientjes@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
ying.huang@intel.com, kirill@shutemov.name,
Andrew Morton <akpm@linux-foundation.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 12/25] mm, compaction: Keep migration source private to a single compaction instance
Date: Thu, 17 Jan 2019 10:40:36 +0100 [thread overview]
Message-ID: <f0f6e34d-8ba0-e394-c91f-3c1d13972969@suse.cz> (raw)
In-Reply-To: <20190104125011.16071-13-mgorman@techsingularity.net>
On 1/4/19 1:49 PM, Mel Gorman wrote:
> Due to either a fast search of the free list or a linear scan, it is
> possible for multiple compaction instances to pick the same pageblock
> for migration. This is lucky for one scanner and increased scanning for
> all the others. It also allows a race between requests on which first
> allocates the resulting free block.
>
> This patch tests and updates the pageblock skip for the migration scanner
> carefully. When isolating a block, it will check and skip if the block is
> already in use. Once the zone lock is acquired, it will be rechecked so
> that only one scanner can set the pageblock skip for exclusive use. Any
> scanner contending will continue with a linear scan. The skip bit is
> still set if no pages can be isolated in a range. While this may result
> in redundant scanning, it avoids unnecessarily acquiring the zone lock
> when there are no suitable migration sources.
>
> 1-socket thpscale
> 4.20.0 4.20.0
> findmig-v2r15 isolmig-v2r15
> Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
> Amean fault-both-3 3505.69 ( 0.00%) 3066.68 * 12.52%*
> Amean fault-both-5 5794.13 ( 0.00%) 4298.49 * 25.81%*
> Amean fault-both-7 7663.09 ( 0.00%) 5986.99 * 21.87%*
> Amean fault-both-12 10983.36 ( 0.00%) 9324.85 ( 15.10%)
> Amean fault-both-18 13602.71 ( 0.00%) 13350.05 ( 1.86%)
> Amean fault-both-24 16145.77 ( 0.00%) 13491.77 * 16.44%*
> Amean fault-both-30 19753.82 ( 0.00%) 15630.86 * 20.87%*
> Amean fault-both-32 20616.16 ( 0.00%) 17428.50 * 15.46%*
>
> This is the first patch that shows a significant reduction in latency as
> multiple compaction scanners do not operate on the same blocks. There is
> a small increase in the success rate
>
> 4.20.0-rc6 4.20.0-rc6
> findmig-v1r4 isolmig-v1r4
> Percentage huge-3 90.58 ( 0.00%) 95.84 ( 5.81%)
> Percentage huge-5 91.34 ( 0.00%) 94.19 ( 3.12%)
> Percentage huge-7 92.21 ( 0.00%) 93.78 ( 1.71%)
> Percentage huge-12 92.48 ( 0.00%) 94.33 ( 2.00%)
> Percentage huge-18 91.65 ( 0.00%) 94.15 ( 2.72%)
> Percentage huge-24 90.23 ( 0.00%) 94.23 ( 4.43%)
> Percentage huge-30 90.17 ( 0.00%) 95.17 ( 5.54%)
> Percentage huge-32 89.72 ( 0.00%) 93.59 ( 4.32%)
>
> Compaction migrate scanned 54168306 25516488
> Compaction free scanned 800530954 87603321
>
> Migration scan rates are reduced by 52%.
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
next prev parent reply other threads:[~2019-01-17 9:40 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-04 12:49 [PATCH 00/25] Increase success rates and reduce latency of compaction v2 Mel Gorman
2019-01-04 12:49 ` [PATCH 01/25] mm, compaction: Shrink compact_control Mel Gorman
2019-01-04 12:49 ` [PATCH 02/25] mm, compaction: Rearrange compact_control Mel Gorman
2019-01-04 12:49 ` [PATCH 03/25] mm, compaction: Remove last_migrated_pfn from compact_control Mel Gorman
2019-01-04 12:49 ` [PATCH 04/25] mm, compaction: Remove unnecessary zone parameter in some instances Mel Gorman
2019-01-15 11:43 ` Vlastimil Babka
2019-01-04 12:49 ` [PATCH 05/25] mm, compaction: Rename map_pages to split_map_pages Mel Gorman
2019-01-15 11:59 ` Vlastimil Babka
2019-01-04 12:49 ` [PATCH 06/25] mm, compaction: Skip pageblocks with reserved pages Mel Gorman
2019-01-15 12:10 ` Vlastimil Babka
2019-01-15 12:50 ` Mel Gorman
2019-01-16 9:42 ` Mel Gorman
2019-01-04 12:49 ` [PATCH 07/25] mm, migrate: Immediately fail migration of a page with no migration handler Mel Gorman
2019-01-04 12:49 ` [PATCH 08/25] mm, compaction: Always finish scanning of a full pageblock Mel Gorman
2019-01-04 12:49 ` [PATCH 09/25] mm, compaction: Use the page allocator bulk-free helper for lists of pages Mel Gorman
2019-01-15 12:39 ` Vlastimil Babka
2019-01-16 9:46 ` Mel Gorman
2019-01-04 12:49 ` [PATCH 10/25] mm, compaction: Ignore the fragmentation avoidance boost for isolation and compaction Mel Gorman
2019-01-15 13:18 ` Vlastimil Babka
2019-01-04 12:49 ` [PATCH 11/25] mm, compaction: Use free lists to quickly locate a migration source Mel Gorman
2019-01-16 13:15 ` Vlastimil Babka
2019-01-16 14:33 ` Mel Gorman
2019-01-16 15:00 ` Vlastimil Babka
2019-01-16 15:43 ` Mel Gorman
2019-01-04 12:49 ` [PATCH 12/25] mm, compaction: Keep migration source private to a single compaction instance Mel Gorman
2019-01-16 15:45 ` Vlastimil Babka
2019-01-16 16:15 ` Mel Gorman
2019-01-17 9:29 ` Vlastimil Babka
2019-01-17 9:40 ` Vlastimil Babka [this message]
2019-01-04 12:49 ` [PATCH 13/25] mm, compaction: Use free lists to quickly locate a migration target Mel Gorman
2019-01-17 14:36 ` Vlastimil Babka
2019-01-17 15:51 ` Mel Gorman
2019-01-04 12:50 ` [PATCH 14/25] mm, compaction: Avoid rescanning the same pageblock multiple times Mel Gorman
2019-01-17 15:16 ` Vlastimil Babka
2019-01-17 16:00 ` Mel Gorman
2019-01-04 12:50 ` [PATCH 15/25] mm, compaction: Finish pageblock scanning on contention Mel Gorman
2019-01-17 16:38 ` Vlastimil Babka
2019-01-17 17:11 ` Mel Gorman
2019-01-18 8:57 ` Vlastimil Babka
2019-01-04 12:50 ` [PATCH 16/25] mm, compaction: Check early for huge pages encountered by the migration scanner Mel Gorman
2019-01-17 17:01 ` Vlastimil Babka
2019-01-17 17:35 ` Mel Gorman
2019-01-04 12:50 ` [PATCH 17/25] mm, compaction: Keep cached migration PFNs synced for unusable pageblocks Mel Gorman
2019-01-17 17:17 ` Vlastimil Babka
2019-01-17 17:37 ` Mel Gorman
2019-01-04 12:50 ` [PATCH 18/25] mm, compaction: Rework compact_should_abort as compact_check_resched Mel Gorman
2019-01-17 17:27 ` Vlastimil Babka
2019-01-04 12:50 ` [PATCH 19/25] mm, compaction: Do not consider a need to reschedule as contention Mel Gorman
2019-01-17 17:33 ` Vlastimil Babka
2019-01-17 18:05 ` Mel Gorman
2019-01-04 12:50 ` [PATCH 20/25] mm, compaction: Reduce unnecessary skipping of migration target scanner Mel Gorman
2019-01-17 17:58 ` Vlastimil Babka
2019-01-17 19:39 ` Mel Gorman
2019-01-18 9:09 ` Vlastimil Babka
2019-01-04 12:50 ` [PATCH 21/25] mm, compaction: Round-robin the order while searching the free lists for a target Mel Gorman
2019-01-18 9:17 ` Vlastimil Babka
2019-01-04 12:50 ` [PATCH 22/25] mm, compaction: Sample pageblocks for free pages Mel Gorman
2019-01-18 10:38 ` Vlastimil Babka
2019-01-18 13:44 ` Mel Gorman
2019-01-04 12:50 ` [PATCH 23/25] mm, compaction: Be selective about what pageblocks to clear skip hints Mel Gorman
2019-01-18 12:55 ` Vlastimil Babka
2019-01-18 14:10 ` Mel Gorman
2019-01-04 12:50 ` [PATCH 24/25] mm, compaction: Capture a page under direct compaction Mel Gorman
2019-01-18 13:40 ` Vlastimil Babka
2019-01-18 14:39 ` Mel Gorman
2019-01-04 12:50 ` [PATCH 25/25] mm, compaction: Do not direct compact remote memory Mel Gorman
2019-01-18 13:51 ` Vlastimil Babka
2019-01-18 14:46 ` Mel Gorman
2019-01-07 23:43 ` [PATCH 00/25] Increase success rates and reduce latency of compaction v2 Andrew Morton
2019-01-08 9:12 ` Mel Gorman
2019-01-09 11:13 ` [PATCH] mm, compaction: Use free lists to quickly locate a migration target -fix Mel Gorman
2019-01-09 19:27 ` Andrew Morton
2019-01-09 21:26 ` Mel Gorman
2019-01-09 11:15 ` [PATCH] mm, compaction: Finish pageblock scanning on contention -fix Mel Gorman
2019-01-09 11:16 ` [PATCH] mm, compaction: Round-robin the order while searching the free lists for a target -fix Mel Gorman
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