Messages in this thread | | | Date | Wed, 28 Jul 2010 11:35:29 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [RFC][PATCH 2/7][memcg] cgroup arbitarary ID allocation |
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On Tue, 27 Jul 2010 22:30:27 -0400 Vivek Goyal <vgoyal@redhat.com> wrote:
> > Index: mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > > =================================================================== > > --- mmotm-2.6.35-0719.orig/Documentation/cgroups/cgroups.txt > > +++ mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > > @@ -621,6 +621,15 @@ and root cgroup. Currently this will onl > > the default hierarchy (which never has sub-cgroups) and a hierarchy > > that is being created/destroyed (and hence has no sub-cgroups). > > > > +void custom_id(struct cgroup_subsys *ss, struct cgroup *cgrp) > > + > > +Called at assigning a new ID to cgroup subsystem state struct. This > > +is called when ss->use_id == true. If this function is not provided, > > +a new ID is automatically assigned. If you enable ss->use_id, > > +you can use css_lookup() and css_get_next() to access "css" objects > > +via IDs. > > + > > Couple of lines to explain why a subsystem would like to assign its > own ids and not be happy with generic cgroup assigned id be helpful. > In this case, I think you are using this id as index into array > and want to control the index, hence you seem to be doing it. > > But I am not sure again why do you want to control index? >
Now, the subsystem allocation/id-allocation order is
->create() alloc_id.
Otherwise "id" of memory cgroup is just determined by the place in virtual-indexed array. As memcg = mem_cgroup_base + id
This "id" is determined at create().
If "id" is determined regardless of memory cgroup's placement, it's of no use. My original design of css_id() allocates id in create() but it was moved to generic part. So, this is expected change in my plan.
We have 2 choices. id = alloc_id() create(id) or this patch.
Both are okay for me. But alloc id before create() may add some ugly rollback.
Thanks, -Kame
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