On Feb 4, 2008, at 6:23 PM, Tom Marchant wrote:
On Mon, 4 Feb 2008 15:54:23 -0600, Kelman, Tom wrote:
Tom,
What you and others have said here has really got me thinking. It's
been about 20 years since I was really an MVS System Programmer
getting
into the bowels of the operating system. I've been a performance
tuner
and now a capacity planner for many years. However, what has been
said
here about the variability of CPU time seems to through all my ideas
about capacity planning and charge back algorithms out the window.
------SNIP--------------------------------
--
Tom Marchant
Tom,
The poster didn't say if a sort is involved or some other external
program (like DB2 or Sort for example) in short he didn't say anything.
Its kind of difficult to say as always it depends.
If its just a plain job read a record process, write a record and
then it gets a little clearer but he didn't specify if the files were
VSAM or ...
There are just too many variables that he did not disclose.
Example: I remember a programmer did a get time for each record and
then did another right after that. Just taking out the request for
time substantially reduced the CPU time (this was 30 years ago) and
asked why the programmer said he thought the system took to long to
run his job and he wanted to know how much time....
Too many unknowns to even hazard a guess, in my opinion.
Ed
Ed
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