Messages in this thread | | | Date | Wed, 31 Aug 2011 23:56:51 +0900 | From | Minchan Kim <> | Subject | Re: [PATCH 3/3] compaction accouting fix |
| |
On Wed, Aug 31, 2011 at 01:37:10PM +0200, Johannes Weiner wrote: > 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>
Thanks, Hannes.
> > 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).
If migrate_pages fails, we reset cc->nr_migratepages to zero in compact_zone. Am I missing something?
> > 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.
-- Kind regards, Minchan Kim
| |