This option specifies the physical CPU that the domain should run VCPU0 on.

In an ordinary machine, the OS would run the process at the head of a queue on the physical CPU.

For performance reasons, we strongly recommend that this be equal to or fewer than the number of physical CPU cores that the domain has available.

This gives the domain two VCPUs, pins the first VCPU to the first physical CPU, and pins the second VCPU to the third physical CPU.