Hi Christoph, On Thu, Nov 01, 2012 at 08:26:09PM +0000, Christoph Lameter wrote: > On Fri, 26 Oct 2012, Minchan Kim wrote: > > > I guess it would improve system performance very well. > > But as I wrote down in description, downside of the patch is that we have to > > age anon lru although we don't have swap. But gain via the patch is bigger than > > loss via aging of anon lru when memory pressure happens. I don't see other downside > > other than it. What do you think about it? > > (I didn't implement anon lru aging in case of no-swap but it's trivial > > once we decide) > > > I am a bit confused like some of the others as to why this patch is > necessary since we already have DONT_NEED. Totally, my fault. I should have written clearly. DONT_NEED have to zap all pte entries/tlb flush when system call happens so DONT_NEED isn't cheap. Even, later if user accesses address again, page fault happens. This patch is to remove above two overheads. while I discussed with KOSAKI, I found there was trial of simillar goal by Rik. https://lkml.org/lkml/2007/4/17/53 But as I look over the code, it seems to have a cost about setting PG_lazyfree on all pages of range which isn't in my implementation. Anyway, I would like to know where Rik's patch wasn't merged at that time. > > -- > 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> -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>