Re: [PATCH 7/8] cgroups: Add a task counter subsystem

Frederic Weisbecker
2011-08-27T14:16:26Z

On Wed, Aug 17, 2011 at 11:18:58AM +0800, Li Zefan wrote:
> > diff --git a/init/Kconfig b/init/Kconfig
> > index 412c21b..bea98d2d 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -690,6 +690,13 @@ config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
> > select this option (if, for some reason, they need to disable it
> > then noswapaccount does the trick).
> >
> > +config CGROUP_TASK_COUNTER
> > + bool "Control number of tasks in a cgroup"
>
> TAB

I suck at configuring emacs correctly, it always makes me do some crazy things
on Kconfig files.

>
> > + depends on RESOURCE_COUNTERS
> > + help
> > + This option let the user to set up an upper bound allowed number
>
> will let?

First of all I should just not start with "This option ..." :)

>
> > + of tasks inside a cgroup.
> > +
> > config CGROUP_PERF
> > bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
> > depends on PERF_EVENTS && CGROUPS
>
> ...
>
> > +int cgroup_task_counter_fork(struct task_struct *child)
> > +{
> > + struct cgroup_subsys_state *css = child->cgroups->subsys[tasks_subsys_id];
> > + struct cgroup *cgrp = css->cgroup;
> > + struct res_counter *limit_fail_at;
> > +
> > + /* Optimize for the root cgroup case, which doesn't have a limit */
> > + if (!cgrp->parent)
> > + return 0;
> > +
> > + return res_counter_charge(cgroup_task_counter_res(cgrp), 1, &limit_fail_at);
>
> I think we should change the return value of res_counter_charge.
> Currently it returns -ENOMEM when we excceed limit.

Yeah like I said previously in the thread, I need to tweak that from
res_counter API.

>
> > +}
> > +
> > +struct cgroup_subsys tasks_subsys = {
> > + .name = "tasks",
> > + .subsys_id = tasks_subsys_id,
> > + .create = task_counter_create,
> > + .post_clone = task_counter_post_clone,
> > + .destroy = task_counter_destroy,
> > + .exit = task_counter_exit,
> > + .can_attach_task = task_counter_can_attach_task,
> > + .cancel_attach_task = task_counter_cancel_attach_task,
> > + .attach_task = task_counter_attach_task,
> > + .populate = task_counter_populate,
> > + .early_init = 1,
>
> Just set early_init to 0, since this subsystem doesn't have to be
> initialized early during kernel boot.

Ah right, now that we don't touch the root cgroup anymore, we can do that
later.

Thanks.