Messages in this thread | | | Date | Thu, 28 Oct 2010 17:13:36 -0700 | Subject | Re: [PATCH 7/7] cgroups: Update documentation for bindable subsystems | From | Paul Menage <> |
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> > Called when a cgroup subsystem is rebound to a different hierarchy > -and root cgroup. Currently this will only involve movement between > -the default hierarchy (which never has sub-cgroups) and a hierarchy > -that is being created/destroyed (and hence has no sub-cgroups). > +and root cgroup. For some subsystems this will only involve movement > +between the default hierarchy (which never has sub-cgroups) and a > +hierarchy that is being created/destroyed (and hence has no sub-cgroups). > +For some other subsystems this can involve movement between the default > +hierarchy and a mounted hierarchy which may have sub-cgroups in it.
This is a bit vague. How about:
For non-bindable subsystems, this will only involve movement between the default hierarchy (which never has sub-cgroups) and a hierarchy that is being created/destroyed (and hence has no sub-cgroups).
For binadable subsystems, this may also involve movement between the default hierarchy and a mounted hierarchy that's populated with sub-cgroups.
Also, the docs should mention that a cgroup setting the can_bind flag has to be able to support side-effect free movement of a task into any just-created cgroup, and into the root cgroup at any time. i.e. it's not suitable for any subsystem where can_attach() might return false for the root cgroup or a newly-created cgroup, or attach() might have side-effects for those same cases.
Actually, perhaps we should forbid the combination of having both an attach() callback and can_bind=true ?
Also, post_clone() doesn't get called when creating the css hierarchy during binding.
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