Re: [PATCH/RFC] msleep() with hrtimers

[Ingo Molnar <mingo@elte.hu>]

* Roman Zippel <zippel@linux-m68k.org> wrote:


> > > One possible problem here is that setting up that timer can be 
> > > considerably more expensive, for a relative timer you have to read 
> > > the current time, which can be quite expensive (e.g. your machine 
> > > now uses the PIT timer, because TSC was deemed unstable).
> >
> > i dont think there's any significant overhead. The OLPC folks are 
> > pretty sensitive to performance, so if there was any genuine 
> > measurable overhead due to this, i'd expect them to report it. And 
> > even if there _was_ overhead, it would be well worth its price, the 
> > legacies of HZ are clearly biting the OLPC project here. The sooner 
> > we get rid of HZ dependencies and HZ artifacts, the better.
>
> How is a sleep function relevant to performace?

i'm not sure how your question relates/connects to what i wrote above, 
could you please re-phrase your question into a bit more verbose form so 
that i can answer it? Thanks,

	Ingo