linux-kernel - Re: [PATCH] memcg: update document to mention swapoff should be test.

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Date:	Mon, 19 Jan 2009 12:42:20 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
	"lizf@...fujitsu.com" <lizf@...fujitsu.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [PATCH] memcg: update document to mention swapoff should be
	test.

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2009-01-19 15:57:48]:

> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> 
> Considering recently found problem:
>  memcg-fix-refcnt-handling-at-swapoff.patch
> 
> It's better to mention about swapoff behavior in memcg_test document.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> ---
>  Documentation/cgroups/memcg_test.txt |   24 ++++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
> 
> Index: mmotm-2.6.29-Jan16/Documentation/cgroups/memcg_test.txt
> ===================================================================
> --- mmotm-2.6.29-Jan16.orig/Documentation/cgroups/memcg_test.txt
> +++ mmotm-2.6.29-Jan16/Documentation/cgroups/memcg_test.txt
> @@ -1,6 +1,6 @@
>  Memory Resource Controller(Memcg)  Implementation Memo.
> -Last Updated: 2008/12/15
> -Base Kernel Version: based on 2.6.28-rc8-mm.
> +Last Updated: 2009/1/19
> +Base Kernel Version: based on 2.6.29-rc2.
> 
>  Because VM is getting complex (one of reasons is memcg...), memcg's behavior
>  is complex. This is a document for memcg's internal behavior.
> @@ -340,3 +340,23 @@ Under below explanation, we assume CONFI
>  	# mount -t cgroup none /cgroup -t cpuset,memory,cpu,devices
> 
>  	and do task move, mkdir, rmdir etc...under this.
> +
> + 9.7 swapoff.
> +	Besides management of swap is one of complicated parts of memcg,
> +	call path of swap-in at swapoff is not same as usual swap-in path..
> +	It's worth to be tested explicitly.
> +
> +	For example, test like following is good.
> +	(Shell-A)
> +	# mount -t cgroup none /cgroup -t memory
> +	# mkdir /cgroup/test
> +	# echo 40M > /cgroup/test/memory.limit_in_bytes
> +	# echo 0 > /cgroup/test/tasks

0? shouldn't this be pid? Potentially echo $$

> +	Run malloc(100M) program under this. You'll see 60M of swaps.
> +	(Shell-B)
> +	# move all tasks in /cgroup/test to /cgroup
> +	# /sbin/swapoff -a
> +	# rmdir /test/cgroup
> +	# kill malloc task.
> +
> +	Of course, tmpfs v.s. swapoff test should be tested, too.
>


-- 
	Balbir
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