Messages in this thread | | | Date | Wed, 11 Jun 2008 14:28:40 -0700 | From | Arjan van de Ven <> | Subject | Re: PROBLEM: no cpu MHz in /proc/cpuinfo on 2.6.25.4-rt6 |
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On Wed, 11 Jun 2008 17:08:09 -0400 Mark Hounschell <markh@compro.net> wrote:
> > > > btw you also changed the problem from "what is the cpu frequency" to > > "how usable is rdtsc for time". My entire point was that these > > weren't related... > > > > > > If they are not the same how do you know at what rate the tsc is > counting.
it's not ticking at the cpu frequency as general rule. For current cpus, your best bet is to calibrate against some external time source... it'll stay constant after that, unless you go to idle, then it may or may not stop (or both). For older cpus it'll change with frequency changes.
-- If you want to reach me at my work email, use arjan@linux.intel.com For development, discussion and tips for power savings, visit http://www.lesswatts.org
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