linux-kernel - Re: [PATCH] mm: disallow direct reclaim page writeback

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Message-Id: <20100416131823.c874125a.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Fri, 16 Apr 2010 13:18:23 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Dave Chinner <david@...morbit.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] mm: disallow direct reclaim page writeback

On Fri, 16 Apr 2010 10:13:39 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:
 
> Hmm. Then, if memoy cgroup is filled by dirty pages, it can't kick writeback
> and has to wait for someone else's writeback ?
> 
> How long this will take ?
> # mount -t cgroup none /cgroup -o memory
> # mkdir /cgroup/A
> # echo 20M > /cgroup/A/memory.limit_in_bytes
> # echo $$ > /cgroup/A/tasks
> # dd if=/dev/zero of=./tmpfile bs=4096 count=1000000
> 
> Can memcg ask writeback thread to "Wake Up Now! and Write this out!" effectively ?
> 

Hmm.. I saw an oom-kill while testing several cases but performance itself
seems not to be far different with or without patch.
But I'm unhappy with oom-kill, so some tweak for memcg will be necessary
if we'll go with this.

Thanks,
-Kame

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