Messages in this thread | | | Date | Fri, 2 Sep 2011 14:09:55 +0900 | Subject | Re: [PATCH 3/3] compaction accouting fix | From | Minchan Kim <> |
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On Thu, Sep 1, 2011 at 11:20 PM, Mel Gorman <mgorman@suse.de> 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. > > s/accouting/accounting/ both here and in the subject. A nicer name the > patch would have been > > "mm: compaction: Only update compact_blocks_moved if compaction was successful"
Thanks, I will fix it at next version. :)
> >> >> 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. >> > > compact_blocks_moved exists to indicate the rate compaction is > scanning pageblocks. If compact_blocks_moved and compact_pages_moved > are increasing at a similar rate for example, it could imply that > compaction is doing a lot of scanning but is not necessarily useful > work. It's not necessarily reflected by compact_fail because that > counter is only updated for pages that were isolated from the LRU.
You seem to say "compact_pagemigrate_failed" not "compact_fail".
> > I now recognise of course that "compact_blocks_moved" was an *awful* > choice of name for this stat.
I hope changing stat names as follows unless it's too late(ie, it doesn't break ABI with any tools)
compact_blocks_moved -> compact_blocks compact_pages_moved -> compact_pgmigrated_success compact_pagemigrate_failed -> compact_pgmigrated_fail compact_stall -> compact_alloc_stall compact_fail -> compact_alloc_fail compact_success -> compact_alloc_success
> > -- > Mel Gorman > SUSE Labs >
-- Kind regards, Minchan Kim
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