The Tuner's Workbench: A Tool to Support Tuning in the Large

. The evident difficulties in creating efficient parallel programs have encouraged the development of computer-based support tools for performance analysis. Our work focuses on gaining a better understanding of the task of performance analysis and tuning, and using this to establish where computer-based support can be most effectively applied. We distinguish between the difficulties inherent in tuning in the small and in tuning in the large and relate these to the design of the Tuner's workbench. 1. Introduction Parallel program performance analysis and tuning is concerned with achieving efficient utilization of machine resources. One common technique is to collect trace data and then analyse it for possible causes of poor performance. The source code is then modified in the light of the analysis. In practice, tuning a parallel program is a much more difficult task than this brief sketch suggests. Our work has been to identify what aspects of tuning would most benefit from computer-..