Do-loop-surface: an abstract representation of parallel program performance

Performance is a critical issue in current massively parallel processors. However, delivery of adequate performance is not automatic and performance evaluation tools are required in order to help the programmer to understand the behaviour of a parallel program. In recent years, a wide variety of tools have been developed for this purpose, including tools for monitoring and evaluating performance and viaualization tools. However, these tools do not provide an abstract representation of performance. Massively parallel processors can generate a huge amount of performance data, and sophisticated methods for representing and displaying these data (e.g. visual and aural) are required. Performance views are not scalable in general and do not represent an abstraction of the performance data.The do-loop-surface display is proposed as an abstract representation of the performance of a particular do-loop in a program. It has been used to improve the performance of a matrix multiply parallel algorithm as well as to understand the behaviour of the following applications: matrix transposition (TRANS1) and fast fourier transform (FFT1) from the Genesis benchmarks, and the kernel of a fluid dynamics package (FIRE). These experiments were performed on a CM-5, a Meiko CS-1 and a PARSYS Supernode. The examples demonstrate that the do-loop-surface display is a useful way to represent performance. It is implemented using AVS (application visualization system), a standard data visualization package.