Re: [PATCH] scheduler cleanup

Borislav Deianov (borislav@lix.polytechnique.fr)
Thu, 14 Oct 1999 17:52:40 +0200

On Thu, Oct 14, 1999 at 03:25:45AM +0100, Artur Skawina wrote:
> Borislav Deianov wrote:
> >
> > > o sched_yield() works better for SCHED_OTHER threads, ie a process
> > > calling sched_yield() won't continue to run if there are other
> > > "normal" processes waiting for a CPU
> >
> > I bet you don't mean that, it still depends on the dynamic
> > priority.
>
> No, i meant what i said above. While returning from
> sched_yield() the current SCHED_OTHER thread will be treated
> just like if it had current->counter==0.

OK, I see - goodness() will return 0 if SCHED_YIELD is set for a
process.

> > I think I see what Andrea means here. Scenario: CPU 0 runs process A,
> > CPU 1 is idle, runqueue has only A. RT process B wakes up, previously
> > run on CPU 0 and decides switching to CPU 1 is too expensive. Process
> > A calls sched_yield(). You better reschedule.
>
> "decides switching to CPU 1 is too expensive" does not happen when CPU1
> is idle. see wake_up_process()/reschedule_idle().

Andrea is right here.

Best,
Borislav

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