Re: [PATCH 06/40] sched: add wakeup/sleep sched_notifiers and allow NULL notifier ops

Peter Zijlstra
2010-01-18T12:50:42Z

On Mon, 2010-01-18 at 20:31 +0900, Tejun Heo wrote:
> On 01/18/2010 06:57 PM, Peter Zijlstra wrote:
> > On Mon, 2010-01-18 at 09:57 +0900, Tejun Heo wrote:
> >
> >> @@ -2439,6 +2440,8 @@ static inline void ttwu_post_activation(struct task_struct *p, struct rq *rq,
> >> rq->idle_stamp = 0;
> >> }
> >> #endif
> >> + if (success)
> >> + fire_sched_notifiers(p, wakeup);
> >> }
> >>
> >> /**
> >
> > So why can't you call fire_sched_notifier(p, wakeup) right next to
> > activate_task(rq, p, 1) in ttwu_activate() ?
>
> I was worried about calling notifier callback before notifying the
> sched_class of the wakeup. Conceptually, the notifier callback should
> be called after all sched internal stuff about the wakeup finish,
> so...

I'm thinking that we can place it next to activate_task(), if it makes
you feel better you can place them both at the end up ttwu_activate()
instead of in the middle.

Esp. with the callback you have it really doesn't matter.