Increased %VMWAIT for idle VMs after upgrading to ESXi 7.0 U2 or later

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

After upgrading to ESXi 7.0 Update 2 or later, you might notice that virtual machines have increased %VMWAIT values in esxtop, the amount should decrease with higher levels of VM utilization, i.e. it is more likely to be high on idle VMs.

In vRealize Operations (vROps), this metric maps to "CPU | IO Wait (%)" (wait minus idle and swap wait) and virtual machines might trigger the "Virtual machine has CPU contention due to long wait for I/O events" alert.

Environment

VMware vSphere ESXi 7.0.2
VMware vSphere ESXi 7.0.3

Cause

This is a cosmetic accounting issue in which not all of the time vCPUs are halting is correctly attributed to IDLE.

Resolution

There currently is no resolution, please subscribe to the KB to be notified of updates.

Workaround:
To workaround the false positives in vROps, disable the alarm for affected VMs or ESXi hosts on 7.0.2 or later.

Additional Information

Impact/Risks:
There is no performance impact.