On Tue, May 17, 2016 at 03:32:46PM +0300, Kirill A. Shutemov wrote: > Currently, faultaround code produces young pte. This can screw up vmscan > behaviour[1], as it makes vmscan think that these pages are hot and not > push them out on first round. > > Let modify faultaround to produce old pte, so they can easily be > reclaimed under memory pressure. > > This can to some extend defeat purpose of faultaround on machines > without hardware accessed bit as it will not help up with reducing > number of minor page faults. > > We may want to disable faultaround on such machines altogether, but > that's subject for separate patchset. > > [1] https://lkml.kernel.org/r/1460992636-711-1-git-send-email-vinmenon@xxxxxxxxxxxxxx > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Cc: Mel Gorman <mgorman@xxxxxxx> > Cc: Rik van Riel <riel@xxxxxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxxxx> > Cc: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx> > Cc: Minchan Kim <minchan@xxxxxxxxxx> I tested 512M mmap sequential word read test on non-HW access bit system (i.e., ARM) and confirmed it doesn't increase minor fault any more. = old = minor fault: 131291 elapsed time: 6747645 usec = new = minor fault: 131291 elapsed time: 6709263 usec 0.56% benefit Acked-by: Minchan Kim <minchan@xxxxxxxxxx> -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>