From: Michal Hocko <mhocko@suse.cz>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch] mm: memcontrol: avoid charge statistics churn during page migration
Date: Tue, 5 Aug 2014 15:34:28 +0200 [thread overview]
Message-ID: <20140805133428.GH15908@dhcp22.suse.cz> (raw)
In-Reply-To: <20140805131223.GA14734@cmpxchg.org>
On Tue 05-08-14 09:12:23, Johannes Weiner wrote:
> On Tue, Aug 05, 2014 at 02:24:34PM +0200, Michal Hocko wrote:
> > On Mon 04-08-14 16:34:29, Johannes Weiner wrote:
> > > Charge migration currently disables IRQs twice to update the charge
> > > statistics for the old page and then again for the new page.
> > >
> > > But migration is a seemless transition of a charge from one physical
> > > page to another one of the same size, so this should be a non-event
> > > from an accounting point of view. Leave the statistics alone.
> >
> > Moving stats to mem_cgroup_commit_charge sounds logical to me but does
> > this work properly even for the fuse replace page cache case when old
> > and new pages can already live in different memcgs?
>
> We don't migrate if the new page is already charged.
Right you are.
Acked-by: Michal Hocko <mhocko@suse.cz>
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Michal Hocko
SUSE Labs
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prev parent reply other threads:[~2014-08-05 13:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-04 20:34 Johannes Weiner
2014-08-05 12:24 ` Michal Hocko
2014-08-05 13:12 ` Johannes Weiner
2014-08-05 13:34 ` Michal Hocko [this message]
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