Messages in this thread | | | Subject | Re: voluntary-preempt-2.6.9-rc3-mm3-T3 | From | Lee Revell <> | Date | Sat, 09 Oct 2004 01:31:26 -0400 |
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On Sat, 2004-10-09 at 01:23, Con Kolivas wrote: > 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.
I am talking about a mode where we only allow a SCHED_FIFO process to preempt a kernel code path. In every other case it works like !PREEMPT.
This is apparently how kernel preemption worked on SVR4.
Lee
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