How it works…

Although high ready time typically signifies CPU contention, the condition does not always warrant corrective action. If the value of ready time is also accompanied by high used time, then it might signify that the host is overcommitted.

So the used time and ready time of a host might signal contention. However, the host might not be overcommitted due to workload availability.

There might be periods of activity and periods that are idle. So the CPU is not over-committed all the time. Another very common source of high ready time for VMs, even when pCPU utilization is low, is due to storage being slow. A vCPU, which occupies a pCPU, can issue a storage I/O and then sit in the WAIT state on the pCPU, blocking other vCPUs. Other vCPUs accumulate ready time; this vCPU and pCPU accumulate wait time (which is not part of the used or utilized time).