On 2015/5/4 22:09, Mike Galbraith wrote:

On Mon, 2015-05-04 at 14:37 +0200, Peter Zijlstra wrote:

quoted

On Mon, May 04, 2015 at 05:11:10PM +0800, Zefan Li wrote:

quoted

Some degree of flexibility is provided so that you may disable some controllers
in a subtree. For example:

root                  ---> child1
(cpuset,memory,cpu)        (cpuset,memory)
                      \
                       \-> child2
                           (cpu)

Uhm, how does that work? Would a task their effective cgroup be the
first parent that has a controller enabled?

In particular, in your example, if T were part of child1, would its cpu
controller be root?

correct.

That's what I'd hope for.  I wanted to try that cgroup.subtree_control
gizmo to see for myself, but I don't have one, and probably won't get
one until I introduce systemd to my axe (again, it's a slow learner).

I'm testing in an environment without systemd.

You need to mount cgroup with a special option:

  # mount -t cgroup -o __DEVEL__sane_behavior xxx /where

If a cgroup controller has already been mounted without this option,
you won't see it in the unified hierarchy, so firstly you need to
delete all cgroups in it and umount it.