OpenMP and NUMA Architectures I: Investigating Memory Placement on the SGI Origin 3000

The OpenMP programming model is based upon the assumption of uniform memory access. Virtually all current day large scale shared memory computers exhibit some degree of Non-Uniform Memory Access (NUMA). Should OpenMP be extended for NUMA architectures? This paper aims to quantify NUMA effects on the SGI Origin 3000 system as a prelude to answering this important question. We discuss the tools required to study NUMA effects and use them in the study of latency, bandwidth and the solution of a 2-D heat diffusion problem