R. Clayton (rclayton@monmouth.edu)
(no date)
Why am I getting different execution times for my program even though I'm using
the same data set for each run?
It could be due to a lot of things:
How big is the difference between runs? You can't expect to get exactly the
same measurements from one run to the next. A couple of percent difference
from one run to the next is probably not something to worry about.
What system are you running on? If you're running on cslab along with
everybody else, you can't expect to get consistent timings because you're
sharing the machine with 30 or so other people. Even if you're on a
machine by yourself you're still sharing the machine with the os,
particularly if it's a networked machine.
How big's the data set? The longer your program runs, the more likely it
will be interrupted by other programs. On the other hand, the shorter a
program runs, the harder it is to get accurate measurements for run-time.
As we talked about in class, getting accurate, or even useful, timings for
running programs is difficult.
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