On Sun, Feb 20, 2011 at 11:43:36PM +0900, Minchan Kim wrote: > Recently, there are reported problem about thrashing. > (http://marc.info/?l=rsync&m=128885034930933&w=2) > It happens by backup workloads(ex, nightly rsync). > That's because the workload makes just use-once pages > and touches pages twice. It promotes the page into > active list so that it results in working set page eviction. > > Some app developer want to support POSIX_FADV_NOREUSE. > But other OSes don't support it, either. > (http://marc.info/?l=linux-mm&m=128928979512086&w=2) > > By other approach, app developers use POSIX_FADV_DONTNEED. > But it has a problem. If kernel meets page is writing > during invalidate_mapping_pages, it can't work. > It makes for application programmer to use it since they always > have to sync data before calling fadivse(..POSIX_FADV_DONTNEED) to > make sure the pages could be discardable. At last, they can't use > deferred write of kernel so that they could see performance loss. > (http://insights.oetiker.ch/linux/fadvise.html) > > In fact, invalidation is very big hint to reclaimer. > It means we don't use the page any more. So let's move > the writing page into inactive list's head if we can't truncate > it right now. > > Why I move page to head of lru on this patch, Dirty/Writeback page > would be flushed sooner or later. It can prevent writeout of pageout > which is less effective than flusher's writeout. > > Originally, I reused lru_demote of Peter with some change so added > his Signed-off-by. > > Reported-by: Ben Gamari <bgamari.foss@xxxxxxxxx> > Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Acked-by: Rik van Riel <riel@xxxxxxxxxx> > Acked-by: Mel Gorman <mel@xxxxxxxxx> > Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Nick Piggin <npiggin@xxxxxxxxx> > Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> Reviewed-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>