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 <vba...@suse.cz> > Cc: Minchan Kim <minc...@kernel.org> > Cc: Mel Gorman <mgor...@suse.de> > Cc: Joonsoo Kim <iamjoonsoo....@lge.com> > Cc: Bartlomiej Zolnierkiewicz <b.zolnier...@samsung.com> > Cc: Michal Nazarewicz <min...@mina86.com> > Cc: Naoya Horiguchi <n-horigu...@ah.jp.nec.com> > Cc: Christoph Lameter <c...@linux.com> > Cc: Rik van Riel <r...@redhat.com>
Acked-by: David Rientjes <rient...@google.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
