Lawrence Berkeley National Laboratory

APEX-Map is a synthetic performance probe for characterizing access behavior to global data structures. It is designed around concepts for temporal locality and spatial locality and can be used to analyze the performance characteristics of a computing platform across a whole range of localities. It can also be used to compare performance across different architectures or different programming paradigms. In this paper, we present the results of APEX-Map on the Cray X1 and use them to analyze this specific computing platform. We have implemented APEX-Map using MPI, SHMEM, and UPC and compare these three programming paradigms on the Cray X1. We are also going to discuss some performance problems we have found regarding the current MPI library implementation.