On Wed, Apr 27, 2011 at 01:25:19AM +0900, Minchan Kim wrote: > In async mode, compaction doesn't migrate dirty or writeback pages. > So, it's meaningless to pick the page and re-add it to lru list. > > Of course, when we isolate the page in compaction, the page might > be dirty or writeback but when we try to migrate the page, the page > would be not dirty, writeback. So it could be migrated. But it's > very unlikely as isolate and migration cycle is much faster than > writeout. > > So, this patch helps cpu and prevent unnecessary LRU churning. > > Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Cc: Mel Gorman <mgorman@xxxxxxx> > Cc: Rik van Riel <riel@xxxxxxxxxx> > Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> > --- > mm/compaction.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index dea32e3..9f80b5a 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -335,7 +335,7 @@ static unsigned long isolate_migratepages(struct zone *zone, > } > > /* Try isolate the page */ > - if (__isolate_lru_page(page, ISOLATE_BOTH, 0, 0, 0) != 0) > + if (__isolate_lru_page(page, ISOLATE_BOTH, 0, !cc->sync, 0) != 0) > continue; With the suggested flags argument from 1/8, this would look like: flags = ISOLATE_BOTH; if (!cc->sync) flags |= ISOLATE_CLEAN; ? Anyway, nice change indeed! Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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>