9.17.19. Working with NUMA topology for virtual machines

To reduce latency in multiprocessor systems, Non-Uniform Memory Access (NUMA) architecture allows CPUs to access local memory faster than remote memory. This design optimizes performance by prioritizing memory resources that are physically closer to the processor.

A CPU with multiple memory controllers can use any available memory across CPU complexes, regardless of where the memory is located. However, this increased flexibility comes at the expense of performance.

NUMA resource topology refers to the physical locations of CPUs, memory, and PCI devices relative to each other in a NUMA zone. In a NUMA architecture, a NUMA zone is a group of CPUs that has its own processors and memory. Colocated resources are said to be in the same NUMA zone, and CPUs in a zone have faster access to the same local memory than CPUs outside of that zone.

A CPU processing a workload using memory that is outside its NUMA zone is slower than a workload processed in a single NUMA zone. For I/O-constrained workloads, the network interface on a distant NUMA zone slows down how quickly information can reach the application.

Applications can achieve better performance by containing data and processing within the same NUMA zone. For high-performance workloads and applications, such as telecommunications workloads, the cluster must process pod workloads in a single NUMA zone so that the workload can operate to specification.