The maximum number of virtual CPUs that you can assign to a virtual machine is 128. The number of virtual CPUs depends on the number of logical CPUs on the host, and the type of guest operating system that is installed on the virtual machine.
Be aware of the following limitations:
A virtual machine cannot have more virtual CPUs than the number of logical cores on the host. The number of logical CPUs equals the number of physical processor cores on the host. For example, on a host that has 128 logical CPUs, you can configure a virtual machine with up to 128 virtual CPUs.
Not every guest operating system supports Virtual SMP, and guest operating systems that support this functionality might support fewer processors than are available on the host. For information about Virtual SMP support, see the VMware Compatibility Guide at http://www.vmware.com/resources/compatibility.
Hyperthreaded hosts might affect virtual machine performance, depending on the workload. The best practice is to test your workload to determine whether to enable or disable hyperthreading on your hosts.