Re: [patch 9/9] Make use of the Master Timer

[Andi Kleen]

> > Hmm, I wasn't sure. Why is it needed? How outdated can the
> > result of RDTSC / RDTSCP be?
> > 
> > If I do:
> > 	rdtscll(a)
> > 	...
> > 	rdtscll(b)
> > is it guaranteed that (b > a) ?
> 
> On a single CPU this is always guaranteed. Even on AMD.

It's not guaranteed on Intel at least (but happens to work on P4) 

-Andi
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