Messages in this thread | | | Date | Wed, 31 Aug 2011 13:37:10 +0200 | From | Johannes Weiner <> | Subject | Re: [PATCH 3/3] compaction accouting fix |
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On Sun, Nov 13, 2011 at 01:37:43AM +0900, Minchan Kim wrote: > I saw the following accouting of compaction during test of the series. > > compact_blocks_moved 251 > compact_pages_moved 44 > > It's very awkward to me although it's possbile because it means we try to compact 251 blocks > but it just migrated 44 pages. As further investigation, I found isolate_migratepages doesn't > isolate any pages but it returns ISOLATE_SUCCESS and then, it just increases compact_blocks_moved > but doesn't increased compact_pages_moved. > > This patch makes accouting of compaction works only in case of success of isolation. > > CC: Mel Gorman <mgorman@suse.de> > CC: Johannes Weiner <jweiner@redhat.com> > CC: Rik van Riel <riel@redhat.com> > Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
It's a teensy-bit awkward that isolate_migratepages() can return success without actually isolating any new pages, just because there are still some pages left from a previous run (cc->nr_migratepages is maintained across isolation calls).
Maybe isolate_migratepages() should just return an error if compaction should really be aborted and 0 otherwise, and have compact_zone() always check for cc->nr_migratepages itself?
if (isolate_migratepages(zone, cc) < 0) { ret = COMPACT_PARTIAL; goto out; }
if (!cc->nr_migratepages) continue;
...
Just a nit-pick, though. If you don't agree, just leave it as is.
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