Messages in this thread | | | Date | Mon, 4 May 2015 17:11:10 +0800 | From | Zefan Li <> | Subject | Re: [PATCH] sched: Relax a restriction in sched_rt_can_attach() |
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>>> 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) >> >> Whew, that's a relief. Thanks. > > But somehow I'm not feeling a whole lot better. > > "May" means if you don't explicitly take some action to disable group > scheduling, you get it (I don't care if I have an off button), but that > would also seemingly mean that we would then have rt tasks in taskgroups > with no bandwidth allocated, ie you have to make group scheduling for rt > tasks meaningless until a bandwidth appeared, and to make bandwidth > appear, you'd have to stop the world, distribute, continue, no? > > The current "just say no" seems a lot more sensible. >
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...
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