The most important thing is RMPTTOM for reducing the SRM timer pop overhead. Note that Timer DIE processing is uncaptured time.
My IEAOPTxx for running under VM has RMPTTOM=30000 /*REDUCE SRM INVOKATION FREQUENCY ON VM */ And that is a value we set a couple of decades ago, and haven't thought much about it since. You might want it even higher for faster machines than we had back then. I suggested some years ago that SRM should self-tune the timer pop interval to be less frequent at low utilization, but I haven't gotten any traction on that so far.. Jim Mulder -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Wendell Lovewell Sent: Monday, March 4, 2024 6:08 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: How to reduce the overhead of WLM? This is probably a strange question, but is there a way to reduce WLM cpu usage? Here's the situation: - The system is a lightly used development system. Unless something is in a loop (very rare), CPU % probably is usually less than 10%. And except for system regions & CICS, it's rare to have multiple jobs running concurrently. - Only one processor defined to the VM. No ZIIP either. - We are charged for CPU cycles. - WLM is the highest consumer of CPU. JES2, TCPIP, ZFS and SDSFAUX round out the top 5 consumers. There is a lot of information about WLM tuning, but as best I can tell almost none of it relates to reducing WLM usage. From reading the Init & Tuning manual, I'm trying these settings: AIMANAGEMENT=NO HIPERDISPATCH=NO CCCAWMT=450000 RMPTTOM=15000 I was thinking that perhaps reducing whatever processing intervals I could might help. But I can't tell these changes made a difference. (I don't have a tool to measure WLM usage.) Any suggestions would be appreciated. TIA, Wendell ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
