On Thu, Sep 1, 2011 at 11:20 PM, Mel Gorman <mgorman@xxxxxxx> 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>