Re: [PATCH(v2) -mmotm 1/2] memcg move charge of file cache at task migration

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Tue, 30 Mar 2010 10:32:36 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Mon, 29 Mar 2010 13:15:41 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > On Mon, 29 Mar 2010 12:03:21 +0900
> > Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> > 
> > > This patch adds support for moving charge of file cache. It's enabled by setting
> > > bit 1 of <target cgroup>/memory.move_charge_at_immigrate.
> > > 
> > > Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> > > ---
> > >  Documentation/cgroups/memory.txt |    6 ++++--
> > >  mm/memcontrol.c                  |   14 +++++++++++---
> > >  2 files changed, 15 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
> > > index 1b5bd04..f53d220 100644
> > > --- a/Documentation/cgroups/memory.txt
> > > +++ b/Documentation/cgroups/memory.txt
> > > @@ -461,10 +461,12 @@ charges should be moved.
> > >     0  | A charge of an anonymous page(or swap of it) used by the target task.
> > >        | Those pages and swaps must be used only by the target task. You must
> > >        | enable Swap Extension(see 2.4) to enable move of swap charges.
> > > + -----+------------------------------------------------------------------------
> > > +   1  | A charge of file cache mmap'ed by the target task. Those pages must be
> > > +      | mmap'ed only by the target task.
> > 
> > Hmm..my English is not good but..
> > ==
> > A charge of a page cache mapped by the target task. Pages mapped by multiple processes
> > will not be moved. This "page cache" doesn't include tmpfs.
> > ==
> > 
> This is more accurate than mine.
> 
> > Hmm, "a page mapped only by target task but belongs to other cgroup" will be moved ?
> > The answer is "NO.".
> > 
> > The code itself seems to work well. So, could you update Documentation ?
> > 
> Thank you for your advice.
> 
> This is the updated version.
> 
> ===
> From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> 
> This patch adds support for moving charge of file cache. It's enabled by setting
> bit 1 of <target cgroup>/memory.move_charge_at_immigrate.
> 
> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

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