>How about submitting a requirement to IBM that would add a control to WLM >This control would re-classify a ZIIP eligible workload to a different >service class if it spills over to a GCP because you are running your ZIIPS >hot (or hit the "generosity factor" for DB2 work). This service class could >have a lower importance/goal than the original service class. You could >also restrict its CPU consumption using a resource group.
My understanding of how it works internally suggest that would be very difficult. When the system determines that the zIIPs need help, one or more GCPs simply select from the zIIP queue of work as well as the GCP queue (although the GCP queue gets preference). So the system doesn't know what zIIP-eligible work is going to be dispatched on the GCP until it gets dispatched there. At which point it wouldn't make sense to reclassify it. >In other words, have a workload run at high priority on ZIIP, but limit it >if it crosses over to GCP. Along those lines, I've always wanted resource groups on the period level so once something has aged down into a penalty period it could also be constrained. >https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0/perf/src/tpc/db2z_ibmziip.html > >IIPHONORPRIORITY parameter > >The IIPHONORPRIORITY parameter in the IEAOPTxx member of SYS1.PARMLIB >determines whether processes are routed from zIIP specialty engines to ... >I would be very very careful about setting IIPHONORPRIORITY to No in a Db2 >environment Agreed--don't use IIPHONORPRIORITY from IEAOPT if you're on Db2 11 or 12. HONORPRIORITY on a service class level is not so improperly looked at by DB2 though, at least last that I knew. Doing it on a service class basis to restrict your lower importance zIIP eligible work to the zIIPs to help prevent them from increasing the R4HA is a reasonable strategy. Any time you restrict the capacity available for a workload you are potentially impacting performance, but sites make the choice to restrict available capacity to workloads to reduce their software costs all the time. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
