Re: the need for speed

["Eric N. Wilson" <doulos1@xxxxxxxx>]

I can agree with John. The first criteria that I use is to write easy to
read/understand code. Then in testing of batch jobs if performance is bad I
will go back and optimize the process. Of course I try to code efficiently,
i.e.. no invariant code in loops etc...

One thing that would be incredibly helpful is a source level profiler, that
would give you the amount of time spent executing each line and procedure of
code. This would greatly help in deciding what sections of a batch program
could really use the optimization and what you should leave alone. I hate
relying on knowledge that I have acquired over the years to perform
optimizations, and with each release of the operating system or change of
core hardware the things to do could easily become a non issue and in the
worse case your "optimizations" might cause worse performance. In addition
it is very difficult to pass this sort of knowledge on because you do not
remember it until you come across a familiar situation. Then the joys of
running large batch jobs many times for each "optimization" to determine if
you actually helped anything or not is always one of the great pleasures in
life. It would be nice to not rely on anecdotal evidence and be able to use
easily quantifiable data to help in the optimization process.

All in all I believe that I end up optimizing around 1% of the programs that
I write, OLTP applications should be written solely with the goal of making
your code as easy to understand as possible, what user is going to notice
the difference between one one thousandth of a second and a half a second?
But those sort of time differences make worlds of difference when coding
batch programs that run over millions and millions of rows/records.

I know that in ILE programs you can collect profiling data that the
optimizer can use to further optimize your code, has there been any thought
as to making an end user product to profile programs at IBM?

OK I think I have broken my soap box :-)

Thanks
Eric



______________________________________________
Eric N. Wilson
President
Doulos Software & Computer Services
2913 N Alder St
Tacoma WA 98407

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