Hi!
> Seems a bit more complicated than what I had in mind. This is
> touching the scheduler I think we can get away without having to.
> Also, there is no simple implementation for the "slowpath" that can
> guarantee the delay without starting over the loop and hoping not to
> get interrupted or just giving up and doing a massively inaccurate
> delay (like msleep, etc).
>
> I was thinking of something along the lines of this:
>
> udelay()
> {
> if (!is_atomic())
> down_read(&freq_sem);
> /* else
> do nothing since cpufreq can't interrupt you.
> */
>
> call usual code since cpufreq is not going to preempt you.
>
> if (!is_atomic())
> up_read(&freq_sem);
> }
Well, most delays are very short, so...
What about... we decide that cpufreq interruption or switch to
different cpu takes 100usec minimum, and only try to do complex magic
for delays >100usec? Hopefully there's minimum of those :-).
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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