Re: as / scheduler question

Con Kolivas
2003-07-28T23:20:57Z

On Tue, 29 Jul 2003 09:01, Andrew Morton wrote:
> Con Kolivas <kernel@kolivas.org> wrote:
> > Nick
> >
> > With the sheduler work Ingo and I have been doing I was wondering if
> > there was possibly a problem with requeuing kernel threads at certain
> > intervals? Ingo's current version requeues all threads at 25ms and I just
> > wondered if this number might be a multiple or factor of a magic number
> > in the AS workings, as we're seeing a few changes in behaviour with AS
> > only. I'm planning on leaving kernel threads out of this requeuing, but I
> > thought I could also pick your brain.
>
> What does "requeues all threads at 25ms" mean?
>
> The only dependency we should have there is that kblockd should be
> scheduled promptly after it is woken. It is reniced by -10 so it should be
> OK. Renicing it further or making it SCHED_RR/FIFO would be interesting.

Ingo introduced the concept of TIMESLICE_GRANULARITY a while ago. All
processes currently running on the active queue get interrupted in their
timeslice after TIMESLICE_GRANULARITY (currently set at 25ms and the subject
of another thread), and put on the tail of the active array to continue their
timeslice after other processes at the same priority on the active queue get
to run, also for at most TIMESLICE_GRANULARITY. If kblockd is reniced to -10
it wont have a problem unless something else ends up with the same dynamic
priority which would only happen if there are interactive tasks reniced to
-10. If it's the only process on the active array at that priority it
_should_ run unaffected.

Con