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SubjectRe: Timestamp counters on SMP
Alan Cox wrote:
>
> > there are notebooks which change the CPU speed and voltage (and the TSC
> > speed as well), depending on the load. This is a much bigger problem.
>
> Current x86 notebooks dont change the TSC speed. They change the clock duty
> cycle not the clock rate.
>

Correct. Transmeta Longrun and Intel Speedstep do change the clock
frequency, though; however, at least Transmeta will still present a
constant-frequency TSC to the RDTSC instruction. Don't know about
Intel.

(Now, some broken Cyrix chips would lose or not increment the TSC when
throttled.)

-hpa

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