performance enhancement



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performance enhancement

Postby anand4u237 » Mon Jun 27, 2011 11:06 am

I've been assigned a job to improve its run time i found a particular step is taking excessive time to complete, in return it's making wait the other dependent jobs. I found that the step is using Region= 40m. Can somebody suggest if increasing the region parameter will enhance the performance of the step. Or any other suggestion that can help me tune the performance.

Thanks
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Re: performance enhancement

 

Re: performance enhancement

Postby mongan » Mon Jun 27, 2011 11:46 am

First, examine the many threads in the forums about performance. Second, find out why it is taking so long. Is it CPU or I/O that takes so long? If I/O, what kind (VSAM, SEQ, DB2). Then maybe you will have the answer your self, in any case with out more information no one can help you.
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Re: performance enhancement

Postby Robert Sample » Mon Jun 27, 2011 3:22 pm

There are cases where increasing the region parameter improves performance, but those are very rare. Most of the time, performance improvements come from other areas as mongan suggested.
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Re: performance enhancement

Postby Ed Goodman » Tue Jun 28, 2011 9:15 pm

First, congrats on getting a performance assignment, that can be the most fun you've ever had. Plus, if you get good at it, all of your coworkers will think very highly of you.

What's your background? Do you have any measurement tools, like STROBE, or APA? Do you have the ability to find people in your shop that DO have these tools?

I will probably cry a little bit if you come back and say something like "No tools, just got picked at random to fix something I don't understand." That's so frustrating to be in that position.

The first thing you need to do is try to figure out WHY the program is slow, and WHAT would be considered an improvement. Does it run for seven hours? OR is it a fifteen minute job that everyone thinks should run faster?

Take a look at the output from the job and take note of the number of EXCPs for each DD. If one of them is in the millions, then it would be a good place to start looking.

The next step is to open up the code and get a feel for what the program is doing. That way, you can better decide which tuning/rewrite options would be the least amount of work.
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Re: performance enhancement

Postby prino » Wed Jun 29, 2011 1:15 am

What language is the program written in? COBOL or PL/I - if the latter I have plenty of tips.
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Re: performance enhancement

Postby BillyBoyo » Wed Jun 29, 2011 7:11 am

Anand,

We don't have anything to go on.

What is the step doing?

What is the progam? If in-house, what language is it in?

What file-system does it use? (database (which), VSAM, PS)?

Is it CPU-bound (high CPU in relation to elapsed) or IO-bound (low CPU usage, high EXCP count)?
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Re: performance enhancement

Postby enrico-sorichetti » Wed Jun 29, 2011 10:26 am

taking excessive time to complete,


excessive compared to what!

other jobs/things waiting is not a time issue, just a scheduling one

what if a long time to complete is appropriate ?
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