Classification: Confidential Yes the result do make sense.
True story. A small auto insurer had a custom (vendor written) COBOL program used for policy rating. The complaint was every time the rating program ran, the CPU (370/138) would go to 100% utilization. I was asked to investigate. It turns out that every single data field in the program was display (no comp, comp-3 data descriptions). A quick review of the Cobol LISTX reviewed the following sequence for every binary operation. Pack (original data item)--> temp1 Conver to binary temp1 --> temp2 Perform arithmetic operation on temp2 Convert to decimal --> temp1 Unpack/unsign temp1 --> original. The sam was true of every decimal operation (without the CVB/CVD instructions. To finish the story, I did not change a single logic line, only data descriptions. The program run was no longer noticeable after the above changes. BTW, for those tht have never seen on, there was an analog "CPU meter" on the front panel of the 370/138 that was used to validate the results HTH, -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Robert Prins Sent: Sunday, January 19, 2025 9:07 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Does this make any sense? [CAUTION: This Email is from outside the Organization. Unless you trust the sender, Don't click links or open attachments as it may be a Phishing email, which can steal your Information and compromise your Computer.] >From LinkedIn: <quote> 2 weeks ago I received the analysis data from a new client that wanted to reduce their CPU consumption and improve their performance. They sent me the statistical data from their z16 10 LPARS. Information about 89,000+ files. I analyzed their data and found 2,000+ files *that could be improved* and would save CPU when improved. *I pulled out 1 file to demonstrate a Proof of Concept (POC) for the client. I had the client run the POC and it showed a 29% reduction in CPU every time that file will be used. The 29% did not include 3 other major adjustments that would save an addition 14% CPU and cut the I/O by 75%.* This is just 1 file. The other files can save 3% to 52% of their CPU every time they are used in BATCH or ONLINE. </quote> I've been a programmer on IBM since 1985, and the above doesn't make any sense to me, how can changing just one file result in a 43% reduction in CPU usage? I've only ever been using PL/I, and using that I did manage to make some improvements to code, including reducing the CPU usage of a CRC routine by an even larger amount, 99.7% (Yes, ninety-nine-point-seven percent), but that was because the old V2.3.0 PL/I Optimizing compiler was absolute shite at handling unaligned bit-strings, but WTH can you change about a file to get the above reduction in CPU? Robert -- Robert AH Prins robert(a)prino(d)org The hitchhiking grandfather <https://prino.neocities.org/index.html> Some REXX code for use on z/OS <https://prino.neocities.org/zOS/zOS-Tools.html> ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ::DISCLAIMER:: ________________________________ The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. ________________________________ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
