clocking subprocesses

barnburnr at gmail.com barnburnr at gmail.com
Mon Mar 3 18:57:35 CET 2008


Hi,

I've seen several threads on this subject, but haven't (yet) run
across one that answers my specific questions.  This should be really
easy for someone, so here goes:

I'm running some numerical simulations under Ubuntu, and using Python
as my scripting language to automatically manage input and output.  I
need to have a precise performance measurement (CPU time) of how long
it takes to run my simulations.

Right now I have something like:

stime = time.time()
subprocess.call(["./mysim","args"])
ftime = time.time()
print ftime-stime

However, time.time() only gives wall-clock time, so I'm also measuring
the time it takes to run other processes running at the same time.
What I'd rather have is:

stime = time.clock()
subprocess.call(["./mysim","args"])
ftime = time.clock()
print ftime-stime

But this, of course, usually outputs 0, because time.clock() does not
count the CPU ticks of the subprocess.

So, long story short, I need to get CPU time of something I call using
subprocess.call().  I don't want to have to profile my code, since it
will significantly reduce computation time.

Thanks for the advice.

Kevin



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