Virtual CPUs

Virtual CPU Analysis

Specifics - Validate virtual CPUs (vcpu) analysis:

Each virtual machine can have multiple virtual CPUs (vcpus). This gives the machine more processing time. Many servers are set up with multiple vcpus. This can be a good thing - to an extent. Look to see how much CPU each of the vcpus is using. If there are 4 vcpus set up in one machine but only 1 of the vcpus is actually doing work, it adds overhead to the system and increases the potential for spinlocks. A server really only needs more vcpus when there are multiple heavy processes that show performance benefits from running in parallel.

ESAUSCP - Shows virtual machine vcpu utilization

UserID/Class - This shows the UserID of the virtual machine. Click on a line (zview) or zoom (z/VM) to see each of the vcpus for a UserID. Only UserID's with multiple vcpu's will show on this screen/report.

Def/Act - This shows how many defined and active vcpu's for this UserID.

CPU percent Tot - This shows the total percentage of CPU each vcpu is using. Notice if there are vcpus that are consistently not being utilized, which could mean an over allocation of vcpus.

SHARE Value - This shows the SHARE value. Notice that each vcpu shares the total SHARE. The report will show the true split - REDHAT75 has two vcpus with a SHARE value of REL 100 so each vcpu has a SHARE value of REL 50. The screen shows a little more in the Samples column as the system had low utilization at the time so the Total increased slightly (60/60).