The article describes P/sup 3/T, a parameter-based performance prediction tool that estimates performance for parallel programs running on distributed-memory parallel architectures. P/sup 3/T has been carefully designed to address all of the above performance estimation issues. To achieve high estimation accuracy, P/sup 3/T aggressively exploits compiler analysis and optimization information. Our method is based on modeling loop iteration spaces, array access patterns, and data distributions by intersection and volume operations on n-dimensional polytopes. The most critical architecture-specific factors, such as cache line sizes, number of cache lines available, routing policy, start-up times, message transfer time per byte, and so forth, are modeled to reflect the performance impact of the target machine. P/sup 3/T has been developed in the context of the Vienna Fortran Compilation Systems (VFCS), a state-of-the-art parallelization tool for distributed-memory systems. VFCS translates Fortran programs into explicitly parallel message-passing programs. P/sup 3/T successfully guides the interactive and automatic restructuring of programs under this system. The article describes the underlying compilation and programming model and discusses the most critical design decisions made for P/sup 3/T; in addition, it outlines the implementation of the parallel program parameters. Also described are the VFCS context under which P/sup 3/T is applied and the P/sup 3/T graphical user interface.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>