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Date: Wed, 20 Oct 2010 12:31:10 +0900
From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
To: Greg Thelen <gthelen@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, containers@lists.osdl.org,
        Andrea Righi <arighi@develer.com>,
        Balbir Singh <balbir@linux.vnet.ibm.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Minchan Kim <minchan.kim@gmail.com>,
        Ciju Rajan K <ciju@linux.vnet.ibm.com>,
        David Rientjes <rientjes@google.com>,
        Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Subject: Re: [PATCH v3 09/11] memcg: add cgroupfs interface to memcg dirty
 limits
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On Mon, 18 Oct 2010 17:39:42 -0700
Greg Thelen <gthelen@google.com> wrote:

> Add cgroupfs interface to memcg dirty page limits:
>   Direct write-out is controlled with:
>   - memory.dirty_ratio
>   - memory.dirty_limit_in_bytes
> 
>   Background write-out is controlled with:
>   - memory.dirty_background_ratio
>   - memory.dirty_background_limit_bytes
> 
> Other memcg cgroupfs files support 'M', 'm', 'k', 'K', 'g'
> and 'G' suffixes for byte counts.  This patch provides the
> same functionality for memory.dirty_limit_in_bytes and
> memory.dirty_background_limit_bytes.
> 
> Signed-off-by: Andrea Righi <arighi@develer.com>
> Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
> Signed-off-by: Greg Thelen <gthelen@google.com>

Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>

One question: shouldn't we return -EINVAL when writing to dirty(_background)_limit_bytes
a bigger value than that of global one(if any) ? Or do you intentionally
set the input value without comparing it with the global value ?
But, hmm..., IMHO we should check it in __mem_cgroup_dirty_param() or something
not to allow dirty pages more than global limit.


Thanks,
Daisuke Nishimura.