Sizing and Planning for zIIPS:
- To assist in planning for zIIPs, components of z/OS have been enhanced to report both projected zIIP usage and actual zIIP usage.
- The projected usage function (PROJECTCPU) is intended to gather information about CPU time spent executing code which could potentially execute on zIIPs.
- See Capacity Planning for zIIP Specialty Engines
Setting the IEAOPTxx parmlib member option PROJECTCPU=YES directs z/OS to record the amount of work eligible for zIIP [and zAAP] processors. SMF Record Type 72 subtype 3 is input to the RMF post processor. The Workload Activity Report lists workloads by WLM service class. In this report the field APPL% IIPPCP indicates which percentage of an processor is zIIP eligible, (APPL% AAPCP indicates which percentage of a processor is zAAP eligible). SMF Record Type 30 provides more detail on specific address spaces. Finding values as little as 25% for APPL% AAPCP or AAPL% IIPCP can make a new zAAP or zIIP processor worthwhile
- For customers that have installed zIIPs, the reporting functions can provide current zIIP execution information that can be used for optimizing current configurations or for predicting potential future usage.
- To assist in planning for zIIP Assisted IPSec, please see the technical papers on the under Resources for basic sizing guidance for your workload.
- Please also refer to technical publications such as the IBM zEnterprise EC12 Technical Guide for information on understanding current and projected zIIP usage.