I really hope you’re not advising customers to run the zIIP pool at 100%. Key functions such as Db2 DBM1 Deferred Write and Prefetch, as well as Db2 Log Writes, depend on very good access to zIIP.
(This is actually why I first wrote my zIIP Capacity & Performance presentation 10 years ago.) And, to be fair, I see some customers pushing their zIIP utilisation too high, but even they aren’t nearly at 100% Cheers, Martin From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of Andrew Rowley <and...@blackhillsoftware.com> Date: Wednesday, 6 September 2023 at 01:22 To: IBM-MAIN@LISTSERV.UA.EDU <IBM-MAIN@LISTSERV.UA.EDU> Subject: [EXTERNAL] Re: Switching between SMT-1 and SMT-2 On 5/09/2023 10:30 pm, Martin Packer wrote: > And “100% busy” is the wrong criterion – if you want your system to be > performant. Isn't that what WLM is for? 25 years ago I did a WLM conversion on a single CPU system. A single CPU is probably the most difficult to tune. By necessity, it ran at 100% for hours at a time. With appropriate WLM settings it performed fine. You do need a mix of work so you have work that can afford to wait, but it's not like the system needs time to to rest. There's no major difference between idle time and time running lower priority work. Is the situation worse now? There were a lot of things we had to do that went against the conventional wisdom for WLM at the time - the conventional wisdon did NOT work well at 100% or on a single CPU. -- Andrew Rowley Black Hill Software ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN Unless otherwise stated above: IBM United Kingdom Limited Registered in England and Wales with number 741598 Registered office: PO Box 41, North Harbour, Portsmouth, Hants. PO6 3AU ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
