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Date: Mon, 19 Dec 2011 11:16:32 -0500
From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: Anton Vorontsov <anton.vorontsov@linaro.org>,
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        John Stultz <john.stultz@linaro.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: Android low memory killer vs. memory pressure notifications
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(12/19/11 5:39 AM), Alan Cox wrote:
>>    The main downside of this approach is that mem_cg needs 20 bytes per
>>    page (on a 32 bit machine). So on a 32 bit machine with 4K pages
>>    that's approx. 0.5% of RAM, or, in other words, 5MB on a 1GB machine.
>
> The obvious question would be why? Would fixing memcg make more sense ?

Just historical reason. Initial memcg implement by IBM was just crap. 
People need very long time to fix it.


> The only problem I see with having a user space manager is that manager
> probably has to be mlock to avoid awkward fail cases and that may in fact
> make it smaller kernel side.