Virtual NUMA considerations

Non-uniform memory access, also known as NUMA, is designed with memory locality in mind so that pools of adjacent memory are placed in islands called NUMA nodes. Here, memory is divided between physical CPUs into NUMA nodes. In a dual CPU server, half the memory is on NUMA node 0 along with CPU 0, and the other half of memory is on NUMA node 1 with CPU 1. The CPU in NUMA node 0 considers the memory in NUMA node 0 to be local (fast) and the memory in NUMA node 1 to be remote (slower). Because of this, the more memory we can give a VM within a NUMA node, the more efficiently that VM can access its memory.

vSphere 6.5 has made changes to its CPU scheduler to optimize the virtual NUMA topology. In vSphere 6.0, if you were to create a VM with 16 CPUs and two cores per socket, eight Virtual Proximity Domains would be created. If you create a VM with the same configuration in vSphere 6.5, only two Virtual Proximity Domains are created, which match the Physical Proximity...