Generally for this type of measurement, you need to measure the bandwidth as a function of buffer size. This reveals the various L1/L2/L3 bandwidths, as well as

Generally for this type of measurement, you need to measure the bandwidth as a function of buffer size. This reveals the various L1/L2/L3 bandwidths, as well as the main memory bandwidth. There are some really complicated effects as well, such as: TLB cache misses, huge pages, and NUMA. For example, on typical two-socket servers, half the memory is "faster" and half the memory is "slower" because it is attached to the remote CPU. Here's an example: https://images.anandtech.com/doci/17024/BandwidthCPU_575px.png https://images.anandtech.com/doci/17024/BandwidthCPU_575px.p...