Messages in this thread | | | Date | Mon, 23 Jun 2014 12:04:48 +0900 | From | Minchan Kim <> | Subject | Re: [PATCH v3 08/13] mm, compaction: remember position within pageblock in free pages scanner |
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On Fri, Jun 20, 2014 at 05:49:38PM +0200, Vlastimil Babka wrote: > Unlike the migration scanner, the free scanner remembers the beginning of the > last scanned pageblock in cc->free_pfn. It might be therefore rescanning pages > uselessly when called several times during single compaction. This might have > been useful when pages were returned to the buddy allocator after a failed > migration, but this is no longer the case. > > This patch changes the meaning of cc->free_pfn so that if it points to a > middle of a pageblock, that pageblock is scanned only from cc->free_pfn to the > end. isolate_freepages_block() will record the pfn of the last page it looked > at, which is then used to update cc->free_pfn. > > In the mmtests stress-highalloc benchmark, this has resulted in lowering the > ratio between pages scanned by both scanners, from 2.5 free pages per migrate > page, to 2.25 free pages per migrate page, without affecting success rates. > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > Acked-by: David Rientjes <rientjes@google.com> Acked-by: Minchan Kim <minchan@kernel.org>
-- Kind regards, Minchan Kim
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