cpuTimePrecision wrong on Windows?

J. Garrett Morris trevion at gmail.com
Thu Feb 21 03:32:41 EST 2008


Both numbers seem odd to me.

As far as I can tell, GHC uses GetProcessTimes to implement
getCPUTime.  GetProcessTimes returns counts of 100s of nanoseconds,
which isn't the number GHC uses for cpuTimePrecision, but I can't find
anyplace in the API documentation that Microsoft actually guarantees
any non-hardware dependent timing precision.

 /g

On Wed, Feb 20, 2008 at 2:46 AM, Adrian Hey <ahey at iee.org> wrote:
> Adrian Hey wrote:
>  >  At least getCPUTime always seems to
>  > return a multiple of 125000000 (1/8 of cpuTimePrecision).
>
>  Actually, that's wrong. A little more intelligent experimentation
>  reveals that (on my system at least) getCPUTime always returns
>  a multiple of 15625000000 (cpuTimePrecision = 15.625 mS IOW).
>
>  It's still not the same as the figure exported by System.CPUTime
>  though :-(
>
>
>
>  Regards
>  --
>  Adrian Hey
>
>
>
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