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

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Message-ID: <20090119083415.GF6039@balbir.in.ibm.com>
Date:	Mon, 19 Jan 2009 14:04:15 +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 16:15:08]:

> On Mon, 19 Jan 2009 12:42:20 +0530
> Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> 
> > * 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 $$
> > 
> 
> 0 is handled as $$ in cgroup/tasks file.
>

OK, I remember having the 0 discussion for cgroups. Thanks for
clarifying. The test looks good, 0 is a bit confusing, since it is a
valid pid not visible to user space... but that is already done and
closed. Hence,

Acked-by: Balbir Singh <balbir@...ux.vnet.ibm.com> 

-- 
	Balbir
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