Increasing the amount of CPU assigned to a virtual machine

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

This article describes how to increase the assigned CPU cycles of a virtual machine. Increasing the amount of CPU cycles assigned to a virtual machine may be required if its CPU requirements have changed since the time of the virtual machine creation. The article also addresses slow operating system performance caused by insufficient CPU cycles.

Environment

vSphere 7.x

vSphere 8.x

Resolution

Ensure that the virtual machine is powered off.

1) Open the vSphere Client and connect to the ESX Server host or vCenter Server managing the VM.
2) Locate the VM in the VMs and Templates view or Hosts and Clusters view.
3) Right-click the VM and select Edit Settings.
4) In the Virtual Hardware tab, locate the CPU section.
5) Adjust the Number of CPUs field to the desired value.
6) If necessary, modify the CPU Limit or Reservation settings as needed.
7) Click OK or Save to apply the changes, then power on the VM by selecting Power > Power On.

Note: Ensure your ESXi host has sufficient resources for the additional vCPUs. 

If hot add is enabled, you do not need to power off the VM. For details on enabling CPU hot add, refer to the VMware documentation on CPU Hot Add.
https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID-285BB774-CE69-4477-9011-598FEF1E9ACB.html

Additional Information