vSphere 5.0 and later includes support for exposing virtual NUMA topology to guest operating systems, which can improve performance by facilitating guest operating system and application NUMA optimizations.
Virtual NUMA topology is available to hardware version 8 virtual machines and is enabled by default when the number of virtual CPUs is greater than eight. You can also manually influence virtual NUMA topology using advanced configuration options.
The first time a virtual NUMA enabled virtual machine is powered on, its virtual NUMA topology is based on the NUMA topology of the underlying physical host. Once a virtual machines virtual NUMA topology is initialized, it does not change unless the number of vCPUs in that virtual machine is changed.
The virtual NUMA topology does not consider the memory configured to a virtual machine. The virtual NUMA topology is not influenced by the number of virtual sockets and number of cores per socket for a virtual machine.
If the virtual NUMA topology needs to be overridden, see Virtual NUMA Controls.
Enabling CPU HotAdd will disable virtual NUMA. See https://kb.vmware.com/kb/2040375.