Slack: A New Performance Metric for Parallel Programs

Critical Path Profiling is a technique that provides guidance to help programmers try to improve the running time of their program. However, Critical Path Profiling provides only an upper bound estimate of the improvement possible in a parallel program execution. In this paper, we present a new metric, called Slack, to complement Critical Path and provide additional information to parallel programmers about the potential impact of making improvements along the critical path. 1