Mainframe, MVS and zOS Discussion

Hi,

I am not a performance person and have not worked on such activities eough and my question might be trivial. I looked at one fo the summary report with RMF. The reports are on 20-minutes intervals. If we add the values of CPU busy field for this interval the result is over the 100%.  Can anyone please help me to understand why would this happen?

Is it average value for this interval or a peak value? How do they calculate the values?

Since there are quite a few RMF reports, and there is RMF Monitor I, Monitor II, and Monitor III to complicate the report source, you need to provide more information -- and you could even post the report data you are asking about -- to help us out.  The CPU Activity report I most often use has LPAR Busy and MVS Busy but there is no CPU Busy field on the report.

In general, the CPU activity in RMF reports is average per LPAR, so if you start adding them yes you could EASILY go over 100%.  If the LPARs use non-dedicated processors, or one or more LPARs are parked during some part of the interval, or different LPARs use different numbers of processors, CPU busy percentage calculations can get a bit messy.  If they are all dedicated (or all use the same number of processors), and none were parked for the interval, you can merely add up the percentages and divide by the number of LPARs to compute the overall percentage.

Some reports for some RMF Monitors have peak values while others have average values.  Without knowing the precise report you are referring to, it is not really possible to say which is used for that report.

It could be Workload Activity Report that's being asked about. And then summing up gives you percent of an engine, rather than of the processor pool. So it could then go way over 100%.