linux-kernel - Re: [PATCH] memcg: drain all stocks for the cgroup before read usage

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Date:	Mon, 5 Sep 2011 08:59:13 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	"Kirill A. Shutemov" <kirill@...temov.name>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Balbir Singh <bsingharora@...il.com>,
	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] memcg: drain all stocks for the cgroup before read
 usage

On Sun,  4 Sep 2011 04:15:33 +0300
"Kirill A. Shutemov" <kirill@...temov.name> wrote:

> From: "Kirill A. Shutemov" <kirill@...temov.name>
> 
> Currently, mem_cgroup_usage() for non-root cgroup returns usage
> including stocks.
> 
> Let's drain all socks before read resource counter value. It makes
> memory{,.memcg}.usage_in_bytes and memory.stat consistent.
> 
> Signed-off-by: Kirill A. Shutemov <kirill@...temov.name>

Hmm. This seems costly to me. 

If a user chesk usage_in_bytes in a memcg once per 1sec, 
the kernel will call schedule_work on cpus once per 1sec.
So, IMHO, I don't like this.

But if some other guys want this, I'll ack.

BTW, how this affects memory.stat ?

Thanks,
-Kame

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