Re: update on hrtimer based select/poll and range-hrtimers

From: Arjan van de Ven
Date: Sun Sep 07 2008 - 17:07:54 EST


On Sun, 07 Sep 2008 22:46:39 +0200
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > "0.1% of the time" for not-nice, not realtime tasks
> > "0.5% of the time" for nice, not realtime tasks
> > with a cap of 100msec for both.
> >
> > I would like to request feedback on this approach; I think this is
> > better than the "hardcoded steps" as before, but maybe someone can
> > come up with an ever better idea....
>
> logarithms pop to mind (again :-)

and it still doesn't strike me as "oh yeah"

how would you see this work? Can you give a numeric example?

>
> > static unsigned long __estimate_accuracy(struct timespec *tv)
> > {
> > unsigned long slack;
> > int divfactor = 1000;
> >
> > if (task_nice(current))
>
> This triggers for both -nice and +nice tasks, it might be worth
> differentiating between those.

good spotting; will fix.


> >
> > if (current->policy == SCHED_FIFO ||
> > current->policy == SCHED_RR)
> > return 0;
>
> rt_task(current) ?

hmm that's not exactly equivalent.. I can see either but still.


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