lkml.org 
[lkml]   [2009]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC][PATCH 1/4] memcg: fix for mem_cgroup_get_reclaim_stat_from_page
On Fri, 9 Jan 2009 10:02:57 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> > pc = lookup_page_cgroup(page);
> > + smp_rmb();
>
> Do you really need the read memory barrier?
>
Necessary.

> > + if (!PageCgroupUsed(pc))
> > + return NULL;
> > +
>
> In this case we've hit a case where the page is valid and the pc is
> not. This does fix the problem, but won't this impact us getting
> correct reclaim stats and thus indirectly impact the working of
> pressure?
>
- If retruns NULL, only global LRU's status is updated.

Because this page is not belongs to any memcg, we cannot update
any counters. But yes, your point is a concern.

Maybe moving acitvate_page() to
==
do_swap_page()
{
- activate_page()
mem_cgroup_try_charge()..
....
mem_cgroup_commit_charge()....
....
+ activate_page()
}
==
is necessary. How do you think, kosaki ?
Thanks,
-Kame



\
 
 \ /
  Last update: 2009-01-09 05:51    [from the cache]
©2003-2011 Jasper Spaans. Advertise on this site