From: Michal Hocko <mhocko@suse.cz>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@csn.ul.ie>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Minchan Kim <minchan@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"andi.kleen" <andi.kleen@intel.com>,
linux-mm <linux-mm@kvack.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Cgroup: Fix memory accounting scalability in shrink_page_list
Date: Fri, 20 Jul 2012 18:31:15 +0200 [thread overview]
Message-ID: <20120720163115.GA20765@tiehlicka.suse.cz> (raw)
In-Reply-To: <20120720151216.GB1426@cmpxchg.org>
On Fri 20-07-12 17:12:16, Johannes Weiner wrote:
> On Fri, Jul 20, 2012 at 04:38:48PM +0200, Michal Hocko wrote:
> > On Fri 20-07-12 16:16:25, Johannes Weiner wrote:
> > > On Fri, Jul 20, 2012 at 03:53:29PM +0200, Michal Hocko wrote:
> > > > On Thu 19-07-12 16:34:26, Tim Chen wrote:
> > > > [...]
> > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > > > > index 33dc256..aac5672 100644
> > > > > --- a/mm/vmscan.c
> > > > > +++ b/mm/vmscan.c
> > > > > @@ -779,6 +779,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > > > >
> > > > > cond_resched();
> > > > >
> > > > > + mem_cgroup_uncharge_start();
> > > > > while (!list_empty(page_list)) {
> > > > > enum page_references references;
> > > > > struct address_space *mapping;
> > > >
> > > > Is this safe? We have a scheduling point few lines below. What prevents
> > > > from task move while we are in the middle of the batch?
> > >
> > > The batch is accounted in task_struct, so moving a batching task to
> > > another CPU shouldn't be a problem.
> >
> > But it could also move to a different group, right?
>
> The batch-uncharging task will remember the memcg of the first page it
> processes, then pile every subsequent page belonging to the same memcg
> on top. It doesn't matter which group the task is in.
Ahh, you are right. I have missed if (batch->memcg != memcg) at the end
of mem_cgroup_do_uncharge.
Thanks!
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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prev parent reply other threads:[~2012-07-20 16:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-19 23:34 [PATCH] Cgroup: Fix memory accounting scalability in shrink_page_list Tim Chen
2012-07-20 3:19 ` Kamezawa Hiroyuki
2012-07-20 4:25 ` Minchan Kim
2012-07-20 16:38 ` Tim Chen
2012-07-20 6:27 ` Johannes Weiner
2012-07-20 11:19 ` Kirill A. Shutemov
2012-07-20 13:53 ` Michal Hocko
2012-07-20 14:16 ` Johannes Weiner
2012-07-20 14:38 ` Michal Hocko
2012-07-20 15:12 ` Johannes Weiner
2012-07-20 16:31 ` Michal Hocko [this message]
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