Any recommendations on IFL engines? -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Scott Chapman Sent: Thursday, March 14, 2019 11:25 PM To: [email protected] Subject: [EXTERNAL]Re: Effective of SMT with high zIIP usage
My recommendation is to leave SMT turned off until you have a defined need for it. Then when/if you turn it on, evaluate both application responsiveness as well as the standard SMT measurement values. And then generally keep an eye on those values over time. With SMT enabled, understanding effective zIIP capacity becomes "problematic". zIIP CPU time measurements are "adjusted" to be MT1ET. I'd always prefer to buy more real zIIP capacity vs. enabling some additional variable and hard to understand amount of capacity via SMT. We've seen cases where SMT was useful and we've seen cases where SMT was problematic. The majority of the cases are somewhere in-between and may not be worth the measurement issues. I'd say we see more sites with it disabled than enabled. But... if you need more zIIP capacity and can't immediately acquire more real zIIP capacity, it can be a very useful stop-gap measure. That may be the case for you, I don't know. Are you getting much cross-over to the GPs? Do you have a large spikes of work units waiting for a zIIP? I have a presentation out there about SMT that explains the measurements and gives my recommendation for when you might want to try it. Go to https://www.pivotor.com and click on the "Free!" button then find and click through to our presentations. You probably can find it on a number of the conference web sites as I've presented it at the major conferences as well. Scott Chapman Enterprise Performance Strategies On Thu, 14 Mar 2019 15:08:36 +0000, Bill Bishop (TMNA) <[email protected]> wrote: >Anyone have any real-world experience with SMT? > >We have very high zIIP usage, 70% to 80% across 3 zIIPs, right now and have >been asked to evaluate turning on SMT. > >One response was that with high zIIP usage, SMT might not be as effective as >could be, and the other response is that it will make more efficient use of >the zIIPS and allow them to drive higher. > >We are aware of the impact of zIIP overflow to CPs. > >Thanks > >Bill Bishop >Consultant, Mainframe Engineer >Mainframe and Scheduling | Infrastructure Technology Services Toyota >Motor North America [email protected] >Office: (469) 292-5149 >Cell: (502) 316-4386 > >---------------------------------------------------------------------- >For IBM-MAIN subscribe / signoff / archive access instructions, send >email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ________________________________ American National has changed its email addresses to [email protected]. Please update my email address in your contact list, if applicable, at your earliest convenience. Confidentiality: This transmission, including any attachments, is solely for the use of the intended recipient(s). This transmission may contain information that is confidential or otherwise protected from disclosure. The use or disclosure of the information contained in this transmission, including any attachments, for any purpose other than that intended by its transmittal is strictly prohibited. Unauthorized interception of this email is a violation of federal criminal law. If you are not an intended recipient of this transmission, please immediately destroy all copies received and notify the sender. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
