Glossary

CPU Ready

CPU Ready is the time the virtual CPUs of a VMware virtual machine spend waiting for a physical CPU thread to become free so that they can be scheduled. The value accumulates over time: the vSphere Client shows it in milliseconds per sample interval, while esxtop reports it as a percentage of elapsed time (%RDY).

XorMon

How XorMon monitors it

✓Broadcom's esxtop guide describes a %RDY between 5 and 10 percent as worth attention and sets its threshold at 10 percent. The XorMon documentation page adds that under 5% is typically not an issue and that above 10% the impact becomes significant.
✓XorMon graphs CPU Ready as the percentage of time a virtual machine was ready to run but could not be scheduled on a physical CPU.
✓This is the esxtop %RDY value and the "Readiness" metric of the vSphere Client, not the "CPU Ready" summation in milliseconds; the documentation page explains how to convert the summation into a percentage.
✓The "CPU Ready/vCPU" graph shows the total CPU Ready of the whole VM divided by its number of vCPUs, and the "CPU Ready/VM" graph shows the sum over all its vCPU cores.
✓XorMon collects this data from the vCenter REST API and graphs CPU Ready and CPU Co-Stop next to memory, network and disk performance.

XorMon documentation: VMware CPU monitoring: CPU Ready

CPU Ready

How XorMon monitors it

Related terms

Sources