Re: [PATCH v4] sched: automated per session task groups

Américo Wang
2010-12-01T04:56:49Z

On Tue, Nov 30, 2010 at 02:36:22PM -0500, Vivek Goyal wrote:
>
>So again, user will think that task is in cgroup test1 and is being
>controlled by the respective weight but that's not the case.
>
>Even if we prevent autogroup task from being visible in cpu controller
>root group, then comes the question what happens if cpu and some other
>controller is comounted. Say cpuset. Now in that case will task be
>visible in root group task file and can one operate on that. Now showing
>up there does not make much sense as task should still be controllable
>by other controllers and its policies.
>
>So yes, creating a /proc/<pid>/autogroup is dirt cheap and makes the life
>easier in terms of implementation of this patch and it should work well.
>But it is also a new user interface which does not sound too extensible and
>does not seem to cooperate well with cgroup interface.
>
>It also introduces this new notion of niceness for task groups which is sort
>of equivalent to cpu.shares in cpu controller. First of all why should we
>not stick to shares notion even for autogroup. Even if we introduce the notion
>of niceness for groups, IMHO, it should be through cgroup interface instead of
>group niceness for autogroup and shares/weights for cgroup despite the
>fact that in the background they do similar things.
>

Hmm, maybe we can make AUTO_GROUP depend on !CGROUPS?

It seems that autogroup only uses 'struct task_group', no other cgroup things,
so I think that is reasonable and doable.