How to measure elapsed time under Windows?

Jean-Michel Pichavant jeanmichel at
Tue Feb 9 19:23:21 CET 2010

Grant Edwards wrote:
> What's the correct way to measure small periods of elapsed
> time.  I've always used time.clock() in the past:
>    start = time.clock()
>    [stuff being timed]
>    stop  = time.clock()
>    delta = stop-start
> However on multi-processor machines that doesn't work.
> Sometimes I get negative values for delta.  According to
> google, this is due to a bug in Windows that causes the value
> of time.clock() to be different depending on which core in a
> multi-core CPU you happen to be on.   [insert appropriate
> MS-bashing here]
> Is there another way to measure small periods of elapsed time
> (say in the 1-10ms range)?
> Is there a way to lock the python process to a single core so
> that time.clock() works right?

Did you try with the datetime module ?

import datetime
t0 =
t1 = t0 -
Out[4]: 644114


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