* MinChan Kim <minchan.kim@xxxxxxxxx> [2011-02-10 14:41:44]: > I don't know why the part of message is deleted only when I send you. > Maybe it's gmail bug. > > I hope mail sending is successful in this turn. :) > > On Thu, Feb 10, 2011 at 2:33 PM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > > Sorry for late response. > > > > On Fri, Jan 28, 2011 at 8:18 PM, Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote: > >> * MinChan Kim <minchan.kim@xxxxxxxxx> [2011-01-28 16:24:19]: > >> > >>> > > >>> > But the assumption for LRU order to change happens only if the page > >>> > cannot be successfully freed, which means it is in some way active.. > >>> > and needs to be moved no? > >>> > >>> 1. holded page by someone > >>> 2. mapped pages > >>> 3. active pages > >>> > >>> 1 is rare so it isn't the problem. > >>> Of course, in case of 3, we have to activate it so no problem. > >>> The problem is 2. > >>> > >> > >> 2 is a problem, but due to the size aspects not a big one. Like you > >> said even lumpy reclaim affects it. May be the reclaim code could > >> honour may_unmap much earlier. > > > > Even if it is, it's a trade-off to get a big contiguous memory. I > > don't want to add new mess. (In addition, lumpy is weak by compaction > > as time goes by) > > What I have in mind for preventing LRU ignore is that put the page > > into original position instead of head of lru. Maybe it can help the > > situation both lumpy and your case. But it's another story. > > > > How about the idea? > > > > I borrow the idea from CFLRU[1] > > - PCFLRU(Page-Cache First LRU) > > > > When we allocates new page for page cache, we adds the page into LRU's tail. > > When we map the page cache into page table, we rotate the page into LRU's head. > > > > So, inactive list's result is following as. > > > > M.P : mapped page > > N.P : none-mapped page > > > > HEAD-M.P-M.P-M.P-M.P-N.P-N.P-N.P-N.P-N.P-TAIL > > > > Admin can set threshold window size which determines stop reclaiming > > none-mapped page contiguously. > > > > I think it needs some tweak of page cache/page mapping functions but > > we can use kswapd/direct reclaim without change. > > > > Also, it can change page reclaim policy totally but it's just what you > > want, I think. > > I am not sure how this would work, moreover the idea behind min_unmapped_pages is to keep sufficient unmapped pages around for the FS metadata and has been working with the existing code for zone reclaim. What you propose is more drastic re-org of the LRU and I am not sure I have the apetite for it. -- Three Cheers, Balbir -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
