linux-kernel - Re: Android low memory killer vs. memory pressure notifications

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Date:	Tue, 20 Dec 2011 09:30:46 +0900
From:	Hiroyuki Kamezawa <kamezawa.hiroyuki@...il.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
Cc:	Anton Vorontsov <anton.vorontsov@...aro.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Arve Hjønnevåg <arve@...roid.com>,
	Rik van Riel <riel@...hat.com>, Pavel Machek <pavel@....cz>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	Michal Hocko <mhocko@...e.cz>,
	John Stultz <john.stultz@...aro.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: Android low memory killer vs. memory pressure notifications

2011/12/20 KOSAKI Motohiro <kosaki.motohiro@...il.com>:
>> - Use memory controller cgroup (CGROUP_MEM_RES_CTLR) notifications from
>>   the kernel side, plus userland "manager" that would kill applications.
>>
>>   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.
>>
>>   0.5% doesn't sound too bad, but 5MB does, quite a little bit. So,
>>   mem_cg feels like an overkill for this simple task (see the driver at
>>   the very bottom).
>
>
> Kamezawa-san, Is 20bytes/page still correct now? If I remember correctly,
> you improved space efficiency of memcg.
>
Johannes removed 4 bytes. It's in upstream.
Johannes removed 8bytes. It's now in linux-next.
I'm preparing a patch to remove more 4 bytes.

Thanks,
-Kame
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