Re: [PATCH 05/31] sched: Add sched_class->reweight_task()

[Tejun Heo]

On Mon, Dec 12, 2022 at 09:11:36PM +0100, Peter Zijlstra wrote:
> > > Hurmph.. this further propagate the existing problem of thinking that
> > > 'prio' is a useful concept in general (it isn't).
> > 
> > I'm not quite following. Can you please expand on why prio isn't a generally
> > useful concept?
> 
> The whole fixed vs dynamic priority scheduling thing. Specifically
> SCHED_DEADLINE implements a dynamic priority scheme using the sporadic
> task model which just doesn't map well to this single prio value
> (notably every SCHED_DEADLINE task has prio -1, making it impossible to
> order SCHED_DEADLINE tasks based on this).

I see, so the expressive power isn't sufficient to cover some use cases.
Yeah, I mean, it's limited and we can add whatever that's necessary but
given that there are many use cases that make use of priorities, I don't
think SCX can skip supporting it.

Thanks.

-- 
tejun