On Fri, 15 Jan 2010 13:18:04 -0600, Mark Zelden <mark.zel...@zurichna.com> wrote:
>On Fri, 15 Jan 2010 10:58:46 -0600, Staller, Allan <allan.stal...@kbm1.com> >wrote: > >>I have recently been going through a similar situation with 2 different >>service classes. Each has the same importance, but different velocities. >>Each service class can consume all of the available CPU (after online, >>etc.) at any given time. >> >> >> >>A review of my performance results has shown that over time, the desired >>velocities are being achieved. However, the work is not processing as a >>continuous stream of CPU applied to both service classes. What has been >>occurring is that during the RMF interval, the 1st service class will >>consume all available CPU and the 2nd will receive none. A short time >>later, WLM will adjust the dispatching priority and the 2nd service >>class will receive all available CPU, the first none. Needless to say, >>my operators panicked until it was demonstrated that they were not >>"losing time" on the production workloads. >> > >This can't be right. Adjustments to goals / DPs are made every 10 seconds. >Could you imagine if online systems in different service classes with >the same importance behaved this way? For example, CICSPROD with >IMP=2 and DB2PROD with IMP=2. > >Mark Not only that, the "fair share algorithm" change to the dispatcher in MVS/ESA V5 ensures that no address spaces at the same DP as other address spaces will monopolize the CPU. Mark -- Mark Zelden Sr. Software and Systems Architect - z/OS Team Lead Zurich North America / Farmers Insurance Group - ZFUS G-ITO mailto:mark.zel...@zurichna.com z/OS Systems Programming expert at http://expertanswercenter.techtarget.com/ Mark's MVS Utilities: http://home.flash.net/~mzelden/mvsutil.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html