Re: [PATCH v3 4/6] sched/fair: Limit run to parity to the min slice of enqueued entities

[Peter Zijlstra <peterz@infradead.org>]

> > If I set my task’s custom slice to a larger value but another task has a smaller slice,
> > this change will cap my protected window to the smaller slice. Does that mean my custom
> > slice is no longer honored?
> 
> What do you mean by honored ? EEVDF never mandates that a request of
> size slice will be done in one go. Slice mainly defines the deadline
> and orders the entities but not that it will always run your slice in
> one go. Run to parity tries to minimize the number of context switches
> between runnable tasks but must not break fairness and lag theorem.So
> If your task A has a slice of 10ms and task B wakes up with a slice of
> 1ms. B will preempt A because its deadline is earlier. If task B still
> wants to run after its slice is exhausted, it will not be eligible and
> task A will run until task B becomes eligible, which is as long as
> task B's slice.

Right. Added if you don't want wakeup preemption, we've got SCHED_BATCH
for you.