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Re: [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished()

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On Fri, Feb 10, 2017 at 06:23:35PM +0100, Vlastimil Babka wrote:
> When detecting whether compaction has succeeded in forming a high-order page,
> __compact_finished() employs a watermark check, followed by an own search for
> a suitable page in the freelists. This is not ideal for two reasons:
> 
> - The watermark check also searches high-order freelists, but has a less strict
>   criteria wrt fallback. It's therefore redundant and waste of cycles. This was
>   different in the past when high-order watermark check attempted to apply
>   reserves to high-order pages.
> 
> - The watermark check might actually fail due to lack of order-0 pages.
>   Compaction can't help with that, so there's no point in continuing because of
>   that. It's possible that high-order page still exists and it terminates.
> 
> This patch therefore removes the watermark check. This should save some cycles
> and terminate compaction sooner in some cases.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: Mel Gorman <mgorman@techsingularity.net>

-- 
Mel Gorman
SUSE Labs

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[PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka <vbabka@suse.cz> - 2017-02-10 20:20 +0100
  [PATCH v2 03/10] mm, page_alloc: split smallest stolen page in fallback Vlastimil Babka <vbabka@suse.cz> - 2017-02-10 20:20 +0100
    Re: [PATCH v2 03/10] mm, page_alloc: split smallest stolen page in  fallback Mel Gorman <mgorman@techsingularity.net> - 2017-02-13 12:00 +0100
      Re: [PATCH v2 03/10] mm, page_alloc: split smallest stolen page in  fallback Vlastimil Babka <vbabka@suse.cz> - 2017-02-13 12:00 +0100
    Re: [PATCH v2 03/10] mm, page_alloc: split smallest stolen page in  fallback Johannes Weiner <hannes@cmpxchg.org> - 2017-02-14 18:10 +0100
  [PATCH v2 01/10] mm, compaction: reorder fields in struct compact_control Vlastimil Babka <vbabka@suse.cz> - 2017-02-10 20:20 +0100
    Re: [PATCH v2 01/10] mm, compaction: reorder fields in struct  compact_control Mel Gorman <mgorman@techsingularity.net> - 2017-02-13 11:50 +0100
    Re: [PATCH v2 01/10] mm, compaction: reorder fields in struct  compact_control Johannes Weiner <hannes@cmpxchg.org> - 2017-02-14 17:40 +0100
  [PATCH v2 06/10] mm, compaction: add migratetype to compact_control Vlastimil Babka <vbabka@suse.cz> - 2017-02-10 20:20 +0100
    Re: [PATCH v2 06/10] mm, compaction: add migratetype to  compact_control Mel Gorman <mgorman@techsingularity.net> - 2017-02-13 12:00 +0100
    Re: [PATCH v2 06/10] mm, compaction: add migratetype to  compact_control Johannes Weiner <hannes@cmpxchg.org> - 2017-02-14 19:20 +0100
  [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished() Vlastimil Babka <vbabka@suse.cz> - 2017-02-10 20:20 +0100
    Re: [PATCH v2 02/10] mm, compaction: remove redundant watermark  check in compact_finished() Mel Gorman <mgorman@techsingularity.net> - 2017-02-13 11:50 +0100
    Re: [PATCH v2 02/10] mm, compaction: remove redundant watermark  check in compact_finished() Johannes Weiner <hannes@cmpxchg.org> - 2017-02-14 17:40 +0100
  Re: [PATCH v2 00/10] try to reduce fragmenting fallbacks Mel Gorman <mgorman@techsingularity.net> - 2017-02-13 12:10 +0100
    Re: [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka <vbabka@suse.cz> - 2017-02-15 15:40 +0100
      Re: [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka <vbabka@suse.cz> - 2017-02-15 17:20 +0100
        Re: [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka <vbabka@suse.cz> - 2017-02-15 21:20 +0100
      Re: [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka <vbabka@suse.cz> - 2017-02-16 16:20 +0100
        Re: [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka <vbabka@suse.cz> - 2017-02-17 16:30 +0100
    Re: [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka <vbabka@suse.cz> - 2017-02-20 13:40 +0100
      Re: [PATCH v2 00/10] try to reduce fragmenting fallbacks Mel Gorman <mgorman@techsingularity.net> - 2017-02-23 17:10 +0100

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