[Devel] Re: Unable to remove control groups on 2.6.23-rc8-mm1

[Balbir Singh]

Badari Pulavarty wrote:
> Hi,
> 
> I am playing with control groups on 2.6.23-rc8-mm1.
> 
> I am able to mount cgroup and create subgroups. I was able
> to move some tasks into them. But, after killing tasks I am
> not able to remove the subgroups. Any idea on why ?
> 
> Thanks,
> Badari
> 

Badari,

We account for page cache usage as well now, I suspect you
most likely have page/swap cache pages charged to the container.

You can try several options (some documented in Documentation/
controllers/memory.txt)

1. Try executing sync; echo 1 > /proc/sys/vm/drop_caches
   and then remove the directory
2. Prior to assigning tasks, set memory.control_type to 1,
   that tracks only RSS pages. You'll find memory.usage_in_bytes
   go to zero as soon as all the tasks exit
3. Set notify_on_release and use the release_agent and releasable
   to free the container once all pages charged to it are freed.

I wonder if I should provide a force_reclaim (hard to guarantee
it will work) for each container, so that the container can
be freed.

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
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