[patch] hp-timing for powerpc64
Benjamin Herrenschmidt
benh@kernel.crashing.org
Mon Jun 20 04:27:00 GMT 2005
On Sat, 2005-06-18 at 08:09 -0700, Ulrich Drepper wrote:
> Paul Mackerras wrote:
>
> > Do we use rdtsc on x86 machines? If not rdtsc, what do we use?
>
> Yes, we do, but at least it means that each unit is one cycle of t he
> CPU which then can be translated into seconds. From what I know this
> isn't the case with mftb, where different implementations increment the
> counter differently.
Note that the vDSO page hast the calibration infos... So with vDSO
enabled kernels either he could just use gettimeofday (which is really
fast) or I could add some additional routine to the vDSO for 2.6.13 that
returns the timebase calibration if you think that is useful for the
generically.
Ben.
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