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From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH 09/22] mm, compaction: Use free lists to quickly locate a migration source
Date: Fri, 8 Feb 2019 18:10:47 +0100	[thread overview]
Message-ID: <7b698aca-bd47-7d5c-a114-145b813b7bdb@suse.cz> (raw)
In-Reply-To: <20190118175136.31341-10-mgorman@techsingularity.net>

On 1/18/19 6:51 PM, Mel Gorman wrote:
> The migration scanner is a linear scan of a zone with a potentiall large
> search space.  Furthermore, many pageblocks are unusable such as those
> filled with reserved pages or partially filled with pages that cannot
> migrate. These still get scanned in the common case of allocating a THP
> and the cost accumulates.
> 
> The patch uses a partial search of the free lists to locate a migration
> source candidate that is marked as MOVABLE when allocating a THP. It
> prefers picking a block with a larger number of free pages already on
> the basis that there are fewer pages to migrate to free the entire block.
> The lowest PFN found during searches is tracked as the basis of the start
> for the linear search after the first search of the free list fails.
> After the search, the free list is shuffled so that the next search will
> not encounter the same page. If the search fails then the subsequent
> searches will be shorter and the linear scanner is used.
> 
> If this search fails, or if the request is for a small or
> unmovable/reclaimable allocation then the linear scanner is still used. It
> is somewhat pointless to use the list search in those cases. Small free
> pages must be used for the search and there is no guarantee that movable
> pages are located within that block that are contiguous.
> 
>                                      5.0.0-rc1              5.0.0-rc1
>                                  noboost-v3r10          findmig-v3r15
> Amean     fault-both-3      3771.41 (   0.00%)     3390.40 (  10.10%)
> Amean     fault-both-5      5409.05 (   0.00%)     5082.28 (   6.04%)
> Amean     fault-both-7      7040.74 (   0.00%)     7012.51 (   0.40%)
> Amean     fault-both-12    11887.35 (   0.00%)    11346.63 (   4.55%)
> Amean     fault-both-18    16718.19 (   0.00%)    15324.19 (   8.34%)
> Amean     fault-both-24    21157.19 (   0.00%)    16088.50 *  23.96%*
> Amean     fault-both-30    21175.92 (   0.00%)    18723.42 *  11.58%*
> Amean     fault-both-32    21339.03 (   0.00%)    18612.01 *  12.78%*
> 
>                                 5.0.0-rc1              5.0.0-rc1
>                             noboost-v3r10          findmig-v3r15
> Percentage huge-3        86.50 (   0.00%)       89.83 (   3.85%)
> Percentage huge-5        92.52 (   0.00%)       91.96 (  -0.61%)
> Percentage huge-7        92.44 (   0.00%)       92.85 (   0.44%)
> Percentage huge-12       92.98 (   0.00%)       92.74 (  -0.25%)
> Percentage huge-18       91.70 (   0.00%)       91.71 (   0.02%)
> Percentage huge-24       91.59 (   0.00%)       92.13 (   0.60%)
> Percentage huge-30       90.14 (   0.00%)       93.79 (   4.04%)
> Percentage huge-32       90.03 (   0.00%)       91.27 (   1.37%)
> 
> This shows an improvement in allocation latencies with similar allocation
> success rates.  While not presented, there was a 31% reduction in migration
> scanning and a 8% reduction on system CPU usage. A 2-socket machine showed
> similar benefits.
> 
> [vbabka@suse.cz: Migrate block that was found-fast, some optimisations]
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>

With the followup fix,

Acked-by: Vlastimil Babka <Vbabka@suse.cz>

  parent reply	other threads:[~2019-02-08 17:10 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-18 17:51 [PATCH 00/22] Increase success rates and reduce latency of compaction v3 Mel Gorman
2019-01-18 17:51 ` [PATCH 01/22] mm, compaction: Shrink compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 02/22] mm, compaction: Rearrange compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 03/22] mm, compaction: Remove last_migrated_pfn from compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 04/22] mm, compaction: Remove unnecessary zone parameter in some instances Mel Gorman
2019-01-18 17:51 ` [PATCH 05/22] mm, compaction: Rename map_pages to split_map_pages Mel Gorman
2019-01-18 17:51 ` [PATCH 06/22] mm, migrate: Immediately fail migration of a page with no migration handler Mel Gorman
2019-01-18 17:51 ` [PATCH 07/22] mm, compaction: Always finish scanning of a full pageblock Mel Gorman
2019-01-18 17:51 ` [PATCH 08/22] mm, compaction: Ignore the fragmentation avoidance boost for isolation and compaction Mel Gorman
2019-01-18 17:51 ` [PATCH 09/22] mm, compaction: Use free lists to quickly locate a migration source Mel Gorman
2019-01-31 13:55   ` Vlastimil Babka
2019-01-31 14:12     ` Vlastimil Babka
2019-02-01 15:06     ` Mel Gorman
2019-02-04  8:55       ` [PATCH] mm, compaction: Use free lists to quickly locate a migration source -fix Mel Gorman
2019-02-08 17:10   ` Vlastimil Babka [this message]
2019-01-18 17:51 ` [PATCH 10/22] mm, compaction: Keep migration source private to a single compaction instance Mel Gorman
2019-01-18 17:51 ` [PATCH 11/22] mm, compaction: Use free lists to quickly locate a migration target Mel Gorman
2019-01-31 14:52   ` Vlastimil Babka
2019-02-01 14:51     ` Mel Gorman
2019-02-01 14:58       ` Vlastimil Babka
2019-02-04 12:01         ` [PATCH] mm, compaction: Use free lists to quickly locate a migration source -fix Mel Gorman
2021-01-12  5:19     ` [PATCH] mm, compaction: make sure we isolate a valid freepage when high_pfn is used Rokudo Yan
2021-01-12  9:10       ` Mel Gorman
2021-01-12  9:47         ` [PATCH] mm, compaction: move high_pfn to the for loop scope Rokudo Yan
2021-01-12 10:45           ` Mel Gorman
2021-01-12 10:48           ` Vlastimil Babka
2021-01-12 22:27           ` Andrew Morton
2021-01-18  7:41             ` Rokudo Yan
2021-01-18  9:42               ` Mel Gorman
2019-01-18 17:51 ` [PATCH 12/22] mm, compaction: Avoid rescanning the same pageblock multiple times Mel Gorman
2019-01-18 17:51 ` [PATCH 13/22] mm, compaction: Finish pageblock scanning on contention Mel Gorman
2019-01-18 17:51 ` [PATCH 14/22] mm, compaction: Check early for huge pages encountered by the migration scanner Mel Gorman
2019-01-18 17:51 ` [PATCH 15/22] mm, compaction: Keep cached migration PFNs synced for unusable pageblocks Mel Gorman
2019-01-18 17:51 ` [PATCH 16/22] mm, compaction: Rework compact_should_abort as compact_check_resched Mel Gorman
2019-01-18 17:51 ` [PATCH 17/22] mm, compaction: Do not consider a need to reschedule as contention Mel Gorman
2019-01-18 17:51 ` [PATCH 18/22] mm, compaction: Reduce premature advancement of the migration target scanner Mel Gorman
2019-01-18 17:51 ` [PATCH 19/22] mm, compaction: Round-robin the order while searching the free lists for a target Mel Gorman
2019-01-18 17:51 ` [PATCH 20/22] mm, compaction: Sample pageblocks for free pages Mel Gorman
2019-01-31 15:39   ` Vlastimil Babka
2019-01-18 17:51 ` [PATCH 21/22] mm, compaction: Be selective about what pageblocks to clear skip hints Mel Gorman
2019-01-31 15:45   ` Vlastimil Babka
2019-01-18 17:51 ` [PATCH 22/22] mm, compaction: Capture a page under direct compaction Mel Gorman
2019-01-31 16:11   ` Vlastimil Babka
2019-02-01 14:38     ` [PATCH] mm, compaction: Capture a page under direct compaction -fix Mel Gorman
2019-01-24  8:53 ` [PATCH 00/22] Increase success rates and reduce latency of compaction v3 Mel Gorman

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