Date: Wed, 6 Jan 2010 16:12:11 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: balbir@linux.vnet.ibm.com
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>
Subject: Re: [RFC] Shared page accounting for memory cgroup
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On Wed, 6 Jan 2010 12:31:50 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > No. If it takes long time, locking fork()/exit() for such long time is the bigger
> > issue.
> > I recommend you to add memacct subsystem to sum up RSS of all processes's RSS counting
> > under a cgroup.  Althoght it may add huge costs in page fault path but implementation
> > will be very simple and will not hurt realtime ops.
> > There will be no terrible race, I guess.
> >
> 
> But others hold that lock as well, simple thing like listing tasks and
> moving tasks, etc. I expect the usage of shared to be in the same
> range.
> 

And piles up costs ? I think cgroup guys should pay attention to fork/exit
costs more. Now, it gets slower and slower.
In that point, I never like migrate-at-task-move work in cpuset and memcg.

My 1st objection to this patch is this "shared" doesn't mean "shared between
cgroup" but means "shared between processes".
I think it's of no use and no help to users.

And implementation is 2nd thing.


Thanks,
-Kame

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