So what is regular NUMA?
Frank Denneman, a well-respected VMware peer, posted an excellent blog article that clearly describes NUMA. So I’m going to just give a shout out to him and point you his way.
How is Wide NUMA different?
In the case a virtual machine doesn’t fit into a NUMA node (ie: 8 vcpu VM on dual socket quad core system), all the benefit of memory locality is lost as the scheduler takes the resources it needs across nodes and remote memory access occurs. With Wide NUMA, the scheduler accommodates such a large virtual machine by splitting the workload into multiple NUMA clients, each of which is assigned to a node and then managed by the scheduler as a normal, non-spanning client. This can improve the performance of certain memory‐intensive workloads with low locality (testing shows up to 7% performance improvement).
Another benefit – you don’t need to do anything. This function is provided automatically by vSphere 4.1 and is enabled by default. This technology will further enhance the ability to virtualize much larger workloads with confidence.
