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From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@suse.cz>
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 09:12:23 -0400	[thread overview]
Message-ID: <20140805131223.GA14734@cmpxchg.org> (raw)
In-Reply-To: <20140805122434.GD15908@dhcp22.suse.cz>

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.

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  reply	other threads:[~2014-08-05 13:12 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 [this message]
2014-08-05 13:34     ` Michal Hocko

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