Re: voluntary-preempt-2.6.9-rc3-mm3-T3

[Con Kolivas]

Lee Revell wrote:
> On Sat, 2004-10-09 at 01:09, Con Kolivas wrote:
>
> > Lee Revell writes:
> >
> >
> > > On Thu, 2004-10-07 at 06:52, Ingo Molnar wrote:
> > >
> > > > i've released the -T3 VP patch:
> > > >
> > > >  http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc3-mm3-T3
> > >
> > > With VP and PREEMPT in general, does the scheduler always run the
> > > highest priority process, or do we only preempt if a SCHED_FIFO process
> > > is runnable?
> >
> > Always the highest priority runnable.
>
>
> Hmm, interesting.  Would there be any advantage to a mode where only
> SCHED_FIFO tasks can preempt?  This seems like a much lighter way to
> solve the realtime problem.

No, the linux scheduler has always been preemptible. PREEMPT and VP just 
allows it to preempt kernel code paths as well. It could be modified to 
do such a thing but apart from real time applications it would perform 
very badly overall.

Con

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