Re: [RFC PATCH V3 6/6] sched/fair: Implement starvation monitor

[Peter Zijlstra]

On Tue, Jun 13, 2023 at 03:41:30PM +0200, Daniel Bristot de Oliveira wrote:

> In an 0-laxity scheduler, the server would run at 0-laxity, jumping in
> front of DL tasks... that would break EDF. It would be mixing two
> schedulers in one. It is not required and likely not a good idea either.

I did consider a hybrid 0-laxity and EDF scheduler for mixed
criticality, as have others like Ted Baker IIRC. IIRC it can be done
using an augmented tree, but none of that solves the problems 0-laxity
has (like over preemption and the general problem of playing chicken by
doing things at the *VERY* last possible moment).

I think I did a talk at OSPERT on this at some point many years ago.
Luckily some bright fellow had this semi-partitioned stuff that would
make live much simpler :-)