Analyzing LPAR and PR/SM processor use

The MVSPM CPU Busy Profile Shared LPARs, Hourly Trend report shows how much of the shared physical system is used by all of the nondedicated logical partitions (LPARs).

Figure 1. MVSPM CPU Busy Profile Shared LPARs, Hourly Trend report
MVSPM CPU Busy Profile Shared LPARs, Hourly Trend report

This report shows the processor busy profile for multiple days to ensure the day chosen for additional reports is a representative day. The total processor busy shown here is based on the portion of the system that is being shared by nondedicated partitions. It does not include the processor busy caused by dedicated partitions, because this processing time is recorded separately. Additional reports break this processor busy out by logical partition.

Notes:

  1. If the global performance data control (CONTROL PRF) parameter has been set to N for this system on the Logical Partition Security Parameters Frame (LPSEC), this system can view only the processor usage data for its logical partition. There is no value in the RMF data regarding the setting of this parameter. Therefore, the reports showing LPAR data for all partitions will be incomplete and not reflect the true resource consumption.
  2. An LPAR defined with one dedicated processor on a four-processor system restricts 25% of the physical processor from being shared. This restriction would not be reflected in this report. The report reflects only how much of the remaining 75% is being used.

The MVSPM CPU Busy by Shared LPARs, Hourly Trend report shows how much of the available system processor capacity each nondedicated logical partition is using.

Figure 2. MVSPM CPU Busy by Shared LPARs, Hourly Trend report
MVSPM CPU Busy by Shared LPARs, Hourly Trend report

Dedicated processors are not included as available processor capacity. The processor busy for each logical partition represents a part of the total available processor resource and not the percent of a logical partition’s processor resource.

The MVSPM Percent of Share Used by LPARs, Hourly Trend report shows how much of the allowed share each logical partition is using and is based on the assigned LPAR weights.

Figure 3. MVSPM Percent of Share Used by LPARs report
MVSPM Percent of Share Used by LPARs report

You can use this report to determine if the weights have been set properly or if a specific partition consistently exceeds its allotted share. When a partition exceeds its share, it uses the available processor cycles not being used by the other nondedicated partitions. When the partitions require more processor resources, PR/SM reduces the partition that is exceeding its share first. For capacity and performance reasons, you must understand the impact this reduction will have on meeting workload objectives.

LPAR enhancements have provided the capability to isolate the PR/SM processor time. If the report shows a logical partition called PHYSCAL, then this feature is installed and the PR/SM processor busy time can be isolated from the logical partition time. If the report does not contain a logical partition called PHYSCAL, then the PR/SM processor busy time cannot be isolated. PHYSCAL is a special name and cannot be used as an LPAR name.