Re: [PATCH] memcg: update document to mention swapoff should betest.

From: Balbir Singh
Date: Mon Jan 19 2009 - 03:36:58 EST


* KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> [2009-01-19 16:15:08]:

> On Mon, 19 Jan 2009 12:42:20 +0530
> Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote:
>
> > * KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> [2009-01-19 15:57:48]:
> >
> > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > >
> > > 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@xxxxxxxxxxxxxx>
> > > ---
> > > 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@xxxxxxxxxxxxxxxxxx>

--
Balbir
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