Unexpected increase in CPU Ready values for virtual machines

Products

• VMware vSphere ESXi

Issue/Introduction

When monitoring virtual machine (VM) performance in the vSphere Client, the CPU Ready metric for specific VMs shows an unexpected increase.

Environment

VMware ESXi 8.0

Cause

This issue may occur when a virtual machine is migrated to an ESXi host that is overcommitted. 

Resolution

Follow these steps to identify the ESXi host where the VM was running.
If the timing of a vMotion migration matches the increase in CPU Ready, the destination host's resource are the likely cause. To resolve the issue, migrate the virtual machine to an ESXi host with sufficient available resources.

1. Access the ESXi host via SSH.
2. Navigate to the directory containing the affected virtual machine's files.
   cd /vmfs/volumes/<Datastore Name>/<VirtualMachine Name>/
   
   
3. Show the host history in vmware.log or vmware-<number>.log using the following command.
   grep Hostname vmware*log
   
   

   - Log example
   2025-01-02T09:00:00.342Z In(05) vmx - Hostname=<HostName>
   2025-01-03T09:00:00.417Z In(05) vmx - Hostname=<HostName>
   2025-01-04T09:00:00.153Z In(05) vmx - Hostname=<HostName>

   
   
   
4. If the increase in CPU Ready matches a host migration, the ESXi host resources are the cause.
   Migrate the VM to a host with sufficient resources and confirm that metrics return to normal levels.