Re: [patch 2/2] mm: memcg: count pte references from every memberof the reclaimed hierarchy

From: KAMEZAWA Hiroyuki
Date: Tue Feb 28 2012 - 22:10:41 EST


On Wed, 29 Feb 2012 03:02:46 +0100
Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> On Wed, Feb 29, 2012 at 09:39:46AM +0900, KAMEZAWA Hiroyuki wrote:
> > On Tue, 28 Feb 2012 15:14:49 +0100
> > Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
> > > --- a/mm/vmscan.c
> > > +++ b/mm/vmscan.c
> > > @@ -708,7 +708,8 @@ static enum page_references page_check_references(struct page *page,
> > > int referenced_ptes, referenced_page;
> > > unsigned long vm_flags;
> > >
> > > - referenced_ptes = page_referenced(page, 1, mz->mem_cgroup, &vm_flags);
> > > + referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup,
> > > + &vm_flags);
> >
> >
> > I'm sorry if I don't understand the codes... !sc->target_mem_cgroup case is handled ?
>
> Yes, but it's not obvious from the diff alone. page_referenced() does
> this:
>
> /*
> * If we are reclaiming on behalf of a cgroup, skip
> * counting on behalf of references from different
> * cgroups
> */
> if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
> continue;
>
> As a result, !sc->target_mem_cgroup -- global reclaim -- will never
> ignore references, or put differently, respect references from all
> memcgs, which is what we want.
>
Ah, thank you.

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

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