Calculating Elapsed Time

Christopher Subich csubich.spam.block at
Wed Dec 7 13:09:03 EST 2005

Fredrik Lundh wrote:

> if I run this on the Windows 2K box I'm sitting at right now, it settles
> at 100 for time.time, and 1789772 for time.clock.  on linux, I get 100
> for time.clock instead, and 262144 for time.time.

Aren't the time.clock semantics different on 'nix?  I thought, at least 
on some 'nix systems, time.clock returned a "cpu time" value that 
measured actual computation time, rather than wall-clock time [meaning 
stalls in IO don't count].

This is pretty easily confirmed, at least on one particular system 
(interactive prompt, so the delay is because of typing):

Python 2.2.3 (#1, Nov 12 2004, 13:02:04)
[GCC 3.2.3 20030502 (Red Hat Linux 3.2.3-42)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
 >>> import time
 >>> (c,t) = (time.clock, time.time)
 >>> (nowc, nowt) = (c(), t())
 >>> print (c() - nowc, t() - nowt)
(0.0019519999999999989, 7.6953330039978027)

So caevat programmer when using time.clock; its meaning is different on 
different platforms.

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