Re: Tracing Programs

>Date: Wed, 25 Oct 2000 12:30:18 -0700
>From: Chris Bipes <chris.bipes@cross-check.com>
>
>I have a current string parsing routine that loops thru an array.  I have
>rewritten it to use the C function StrTok.  What I want to do is see if
this
>is really faster than the old loop.  I can also use the scan and substr
BIFs
>to achieve the same results.  Since this is a major time critical
>application I want to use the most efficient way possible.  I do not have
a
>dedicated machine to test on so using job timing does not work.  How can
one
>trace the CPU time used for each transaction?  I have seen machine traces
>before that showed the machine instruction trace of a job.  Where do I
find
>this?  I am on V4R4.

Chris, even without a dedicated machine, you should be able to test this.
Create two programs each containing just the two versions of the code, in a
loop (make sure the code within the loop is just what's needed to do the
tasks
being compared - no unnecessary calls etc).  Have the loop iterate enough
times for the program to run at least 5 minutes.  For this type of program
I always pass the number of times in as a parameter (a perfect use for a
15,5
parm :).

To reduce the effect of other jobs, run the programs alternately 3 or 4
times.
Don't be tempted to take an average of the times taken for each case;
instead
you should compare the best times for each case.  (If the times vary
wildly,
you're right and I'm wrong and you'll have to find another way ...)

To increase your satisfaction that your tests are accurate, try doing the
tests like this (assuming 10000 lets your programs run at least a couple of
minutes):
  call pgma  10000
  call pgmb  10000
  call pgma  50000
  call pgmb  50000
  call pgma 100000
  call pgmb 100000

If pgma's times are x 5x and 10x and pgmb's times are y 5y and 10y, then
you
can be quite sure that it's reasonable to compare x and y.

Barbara Morris


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