Re: [RFC][PATCH 1/7] sched: Replace post_schedule with a balance callback list

[pang . xunlei]

Hi Peter,

This may increase the overhead of schedule() a bit, as it will have 
more work to do.

check_class_changed():
        if (prev_class->switched_from)
                        prev_class->switched_from(rq, p);
                /* Possble rq->lock 'hole'.  */
                p->sched_class->switched_to(rq, p);

For above cases, why can't we just add a judgement in switched_to_fair() 
as follows:
if (rq != task_rq(p))
        return;

switched_to_rt() and switched_to_dl() already did the similar judgement.

Then the following operation is usually task_rq_unlock() or the like, 
seems no other harm with the old rq of p.

-Xunlei

Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote 2015-06-01 PM 09:58:19:
> [RFC][PATCH 1/7] sched: Replace post_schedule with a balance callback 
list
> 
> Generalize the post_schedule() stuff into a balance callback list.
> This allows us to more easily use it outside of schedule() and cross
> sched_class.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

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