Messages in this thread | | | Date | Wed, 19 Aug 2009 20:10:18 +0800 | From | Wu Fengguang <> | Subject | Re: [RFC] respect the referenced bit of KVM guest pages? |
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On Wed, Aug 19, 2009 at 08:05:19PM +0800, KOSAKI Motohiro wrote: > >> page_referenced_file? > >> I think we should change page_referenced(). > > > > Yeah, good catch. > > > >> > >> Instead, How about this? > >> ============================================== > >> > >> Subject: [PATCH] mm: stop circulating of referenced mlocked pages > >> > >> Currently, mlock() systemcall doesn't gurantee to mark the page PG_Mlocked > > > > mark PG_mlocked > > > >> because some race prevent page grabbing. > >> In that case, instead vmscan move the page to unevictable lru. > >> > >> However, Recently Wu Fengguang pointed out current vmscan logic isn't so > >> efficient. > >> mlocked page can move circulatly active and inactive list because > >> vmscan check the page is referenced _before_ cull mlocked page. > >> > >> Plus, vmscan should mark PG_Mlocked when cull mlocked page. > > > > PG_mlocked > > > >> Otherwise vm stastics show strange number. > >> > >> This patch does that. > > > > Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> > > Thanks. > > > > >> Index: b/mm/rmap.c > >> =================================================================== > >> --- a/mm/rmap.c 2009-08-18 19:48:14.000000000 +0900 > >> +++ b/mm/rmap.c 2009-08-18 23:47:34.000000000 +0900 > >> @@ -362,7 +362,9 @@ static int page_referenced_one(struct pa > >> * unevictable list. > >> */ > >> if (vma->vm_flags & VM_LOCKED) { > >> - *mapcount = 1; /* break early from loop */ > >> + *mapcount = 1; /* break early from loop */ > >> + *vm_flags |= VM_LOCKED; /* for prevent to move active list */ > > > >> + try_set_page_mlocked(vma, page); > > > > That call is not absolutely necessary? > > Why? I haven't catch your point.
Because we'll eventually hit another try_set_page_mlocked() when trying to unmap the page. Ie. duplicated with another call you added in this patch.
Thanks, Fengguang
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