OT to your exact question but I think also IBM (I am probably not phrasing this exactly to the party line) wanted to get more experience with SMT before turning it on in their crown jewel operating system. Or perhaps, more bluntly, they have not made the changes to the z/OS dispatcher and WLM necessary to reasonably support SMT.
Repeatable CPU timing is a thing of the past in any event. I have a product where I can demonstrate an almost 3:1 variance in CPU time *for the exact same workload* depending on how fast I push the transactions through the product. Faster push = more cache hits = less CPU time. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Pew, Curtis G Sent: Monday, March 07, 2016 9:40 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Does everybody use chargeback? I’d wondered why SMT is turned off for CPs on the new z13 and z13s. I learned at SHARE that it’s because CPU timing can’t be done as accurately when using SMT, and since that could affect chargeback it’s not allowed. This is interesting, because we’ve never done chargeback here at UT. I was wondering how unusual this makes us. (I know we’re unusual in lots of ways, but I hadn’t thought much about chargeback.) So just to satisfy my curiosity, how many of y’all don’t do chargeback? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
