Messages in this thread | | | Date | Wed, 7 May 2014 14:47:05 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH v2 2/2] mm/compaction: avoid rescanning pageblocks in isolate_freepages |
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On Wed, 7 May 2014, Vlastimil Babka wrote:
> The compaction free scanner in isolate_freepages() currently remembers PFN of > the highest pageblock where it successfully isolates, to be used as the > starting pageblock for the next invocation. The rationale behind this is that > page migration might return free pages to the allocator when migration fails > and we don't want to skip them if the compaction continues. > > Since migration now returns free pages back to compaction code where they can > be reused, this is no longer a concern. This patch changes isolate_freepages() > so that the PFN for restarting is updated with each pageblock where isolation > is attempted. Using stress-highalloc from mmtests, this resulted in 10% > reduction of the pages scanned by the free scanner. > > Note that the somewhat similar functionality that records highest successful > pageblock in zone->compact_cached_free_pfn, remains unchanged. This cache is > used when the whole compaction is restarted, not for multiple invocations of > the free scanner during single compaction. > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Mel Gorman <mgorman@suse.de> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> > Cc: Michal Nazarewicz <mina86@mina86.com> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Cc: Christoph Lameter <cl@linux.com> > Cc: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
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