Right. Though you've never been in my audience :-( you would've got the same message about DB2 V10, a fortiori 11, 12 from me.
Cheers, Martin Martin Packer zChampion, Systems Investigator & Performance Troubleshooter, IBM +44-7802-245-584 email: martin_pac...@uk.ibm.com Twitter / Facebook IDs: MartinPacker Blog: https://www.ibm.com/developerworks/mydeveloperworks/blogs/MartinPacker Podcast Series (With Marna Walle): https://developer.ibm.com/tv/mpt/ or https://itunes.apple.com/gb/podcast/mainframe-performance-topics/id1127943573?mt=2 Youtube channel: https://www.youtube.com/channel/UCu_65HaYgksbF6Q8SQ4oOvA From: Jesse 1 Robinson <jesse1.robin...@sce.com> To: IBM-MAIN@LISTSERV.UA.EDU Date: 07/06/2018 17:54 Subject: Re: Why are highly busy zIIPs worse than highly busy CPs? Sent by: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> We've had zIIPs for years. We monitored usage but were never terribly concerned as long as numbers didn't skyrocket. When we moved to DB2 V10, however, we were warned that 'some customers' were experiencing serious performance problems when zIIP eligible work spilled over to general CPs. The reason, we were told, was that while general CP management had evolved over the decades with a huge boatload of OS code to handle contention, zIIPs were newcomers that were more or less on their own in playground competition. The wiry little guys with little bully protection. The message we got was that an overloaded zIIP could lead to performance problems--and rolling average spikes--that could be worse (!) than having no zIIP at all. We were sufficiently alarmed that we were moved to buy yet another zIIP to guard against calamity in production. Because we acquired the extra zIIP early on, I can't say what the consequence would have been if we had done nothing, but this is certainly the tale I'd rather be telling. . . J.O.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler SHARE MVS Program Co-Manager 323-715-0595 Mobile 626-543-6132 Office ⇐=== NEW robin...@sce.com -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Peter Hunkeler Sent: Thursday, June 07, 2018 9:21 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: (External):AW: Re: Why are highly busy zIIPs worse than highly busy CPs? >Isn't "fall back to the CP" because one would typically want one's work >to run *somewhere* even if a zIIP were not available but perhaps a CP was? If you meant no zIIPs are available to the LPAR (not configured or the CEC does not have some), then there is no fall-back. Work units get queue on CP work queues initially; the zIIP work queue is not being used. At least this is how I understand it. If you meant no free zIIP capacity is available, then part of the decision might have been that initially you could have only half as many zIIPs as you had CPs. -- Peter Hunkeler ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
