On Tue, Nov 30, 2010 at 09:18:22AM +0000, Mel Gorman wrote: > On Tue, Nov 30, 2010 at 10:10:20AM +0900, KOSAKI Motohiro wrote: > > > invalidate_mapping_pages is very big hint to reclaimer. > > > It means user doesn't want to use the page any more. > > > So in order to prevent working set page eviction, this patch > > > move the page into tail of inactive list by PG_reclaim. > > > > > > Please, remember that pages in inactive list are working set > > > as well as active list. If we don't move pages into inactive list's > > > tail, pages near by tail of inactive list can be evicted although > > > we have a big clue about useless pages. It's totally bad. > > > > > > Now PG_readahead/PG_reclaim is shared. > > > fe3cba17 added ClearPageReclaim into clear_page_dirty_for_io for > > > preventing fast reclaiming readahead marker page. > > > > > > In this series, PG_reclaim is used by invalidated page, too. > > > If VM find the page is invalidated and it's dirty, it sets PG_reclaim > > > to reclaim asap. Then, when the dirty page will be writeback, > > > clear_page_dirty_for_io will clear PG_reclaim unconditionally. > > > It disturbs this serie's goal. > > > > > > I think it's okay to clear PG_readahead when the page is dirty, not > > > writeback time. So this patch moves ClearPageReadahead. > > > > > > Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> > > > Acked-by: Rik van Riel <riel@xxxxxxxxxx> > > > Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx> > > > Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > > > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > > > Cc: Nick Piggin <npiggin@xxxxxxxxx> > > > Cc: Mel Gorman <mel@xxxxxxxxx> > > > > I still dislike this one. I doubt this trick makes much benefit in real > > world workload. > > > > I would agree except as said elsewhere, it's a chicken and egg problem. > We don't have a real world test because fadvise is not useful in its > current iteration. I'm hoping that there will be a test comparing > > rsync on vanilla kernel > rsync on patched kernel > rsync+patch on vanilla kernel > rsync+patch on patched kernel > > Are the results of such a test likely to happen? Ben, Could you get the rsync execution time(user/sys) and 'cat /proc/vmstat' result before/after? If Ben is busy, I will try to get a data. but I need enough time. I expect rsync+patch on patched kernel should have a less allocstall, less pgscan so fast execution time. > > -- > Mel Gorman > Part-time Phd Student Linux Technology Center > University of Limerick IBM Dublin Software Lab -- Kind regards, Minchan Kim -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>