Messages in this thread | | | Date | Mon, 4 May 2015 14:37:38 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched: Relax a restriction in sched_rt_can_attach() |
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On Mon, May 04, 2015 at 05:11:10PM +0800, Zefan Li wrote:
> 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?
> I just realized we allow removing/adding controllers from/to cgroups > while there are tasks in them, which isn't safe unless we eliminate all > can_attach callbacks. We've done so for some cgroup subsystems, but > there are still a few of them...
You can't remove can_attach(), we must be able to disallow joining a cgroup.
If that results in you not being able to change the cgroup setup with tasks in, so be it -- that seems like a sane restriction anyhow.
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