Which is a valid reason NOT to set CPU affinity on a single VM?
Setting CPU affinity will monopolize a CPU making it unusable for other VMs on the server.
CPU affinity can only be set on hyperthreaded systems.
A virtual machine with CPU affinity might not receive all of it’s reserved CPU resources.
CPU affinity settings are ignored when using VMotion.
Potential Issues with CPU Affinity
Before you use CPU affinity, you might need to consider certain issues.
Potential issues with CPU affinity include:
Affinity can interfere with the ESX/ESXi host’s ability to meet the reservation and shares specified for a virtual machine.