Tom, Your answer, though, betrays a system programmer (or perhaps just ISV) point of view. The first thing is, application programmers are not always permitted to "gather SMF records", even assuming they know what they are and know how to find and use the tools needed to report on and interpret them. In my shop, DCOLLECT and SMF archives are RACF-protected from use by anyone except authorized personnel. I am given to understand this is not uncommon, and may be an audit requirement.
Management of development areas still are tasked with reducing the CPU consumption and elapsed running times of their applications, regardless of the "well known culprits" being addressed by IBM and ISV's. So they task their programmers with that requirement, and I am asking what I as an application programmer have available to me to measure my results when I make source changes intended to improve performance. Based on this thread, the JES-reported TCB and SRB usage (in JESMSGLG) is unpredictably variable. Those numbers and the Strobe product the only tools I have available to me. In the larger scheme of sysplex-wide throughput and response time the magnitude of application CPU usage may or may not matter, but if I'm given the task to reduce those numbers for a particular application, I need to know what reliable and unrestricted tools are available to measure my results. It's very discouraging to be told "the tools you depend on are unreliable and unpredictably variable". Peter > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > Behalf Of Tom Harper > Sent: Tuesday, February 05, 2008 4:53 PM > To: [email protected] > Subject: Re: CPU time differences for the same job > > Peter, > > The answer is: it may not matter. Some time ago I was asked to do > research to see if the installation I worked for could justify a COBOL > optimizer (this was a while back, but I believe same issues are true > today). I gathered SMF records and sorted them down by total CPU > consumed by PGM=program name in our installation for a month. The > results were very interesting, but I would be also interested to know if > others have done this and what they found out. > > What I found out was the following: > > - About 30% of the CPU was consumed by SORT > - About 10% of the CPU was consumed by IEBGENER > - ... > - About 2% of the CPU was consumed by application COBOL programs. > > The conclusion I drew was that even if you eliminated all of the CPU > used by application COBOL programs, the most one would save is 2%. We > declined to purchase the product. > > It has been my personal experience that a similar, but perhaps different > CPU profile exists in most shops (that is, a list of declining amounts > of CPU time). The products that use large amounts of CPU time are well > known, and a great deal of effort at IBM and ISVs has been expended to > work on this issue. To verify this, just do the same thing on your > particular program for all of the CPU it uses in a month. The small > amount may surprise you. > > Additionally, a portion of the CPU time charged to your program may be > in doing services on your behalf, such as QSAM, various SVCs, etc., over > which you have some, but often times, little control. > > Tom Harper > IMS Utilities Development Team > Neon Enterprise Software > Sugar Land, TX This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
