This is really difficult to do. For a number of reasons, speed does not necessarily scale proportionately with the number of cores: (1) Intel Turbo Boost, whic

This is really difficult to do. For a number of reasons, speed does not necessarily scale proportionately with the number of cores: (1) Intel Turbo Boost, which will run a single core at higher frequency than multiple cores (to make matters worse, this is also dependent on the CPU's temperature). (2) Hyperthreading giving you anywhere between a x2 and no speedup depending on what your code is doing under the hood. (3) NUMA giving, well, non-uniform speedups for some memory access patterns. (4) Background processes occupying 1+ cores.