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Subject: Re: [RFC][PATCH 0/3] Refactoring sched_entity and sched_rt_entity.
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Dario Faggioli <raistlin@linux.it>
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Date: Tue, 04 Jan 2011 17:19:04 +0100
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On Tue, 2011-01-04 at 16:55 +0100, Dario Faggioli wrote:

> They're not inside an union yet, because I'm not sure on how to treat
> the task group case. In fact, tasks can only have _just_one_ scheduling
> policy at a time, and thus, for example, they need the run_list _or_ the
> rb_node for queueing (if the task is RT or fair, respectively), which is
> perfect with respect to using an union.
> OTOH, groups are always considered both fair _and_ RT entities, for
> example they're always queued in _both_ an RT run_list and a fair
> rb-tree. So I can't put them in an union, because I need both at the
> same time!

Just like its now, keep a sched_entity per class.

struct task_group {

#ifdef CONFIG_FAIR_GROUP_SCHED
	struct sched_entity **cfs_se;
	...
#endif

#ifdef CONFIG_RT_GROUP_SCHED
	struct sched_entity **rt_se;
	...
#endif

}

> And as usual, comments of any kind are very very welcome! :-)

Yay!

I see once clash with my current ttwu patch set though, see:

  http://lkml.org/lkml/2011/1/4/228

But that should be easy to resolve.