Program Suitability for Parallel Processing

This paper describes the Fortran parallel task recognizer and the directed graph model upon which it is based. The recognizer is itself a Fortran program. As input the recognizer accepts source programs written in Fortran; as output the recognizer generates a set of tables which communicate to the operating system information regarding the parallel processability of source program tasks. The recognizer has been used to analyze several programs in an attempt to determine what characteristics render a program "suitable" for parallel processing. Timing studies have shown that the detailed recognizer analysis consumes a large amount of time in an attempt to answer the suitability question. For a suitable production-type program this analysis time can be distributed over the lifetime of the program. In those cases where the source program is not suitable for parallel processing, however, this analysis represents a wasted investment of valuable system resources. To circumvent this, a heuristic procedure has been developed which introduces little overhead and provides a preliminary answer to the suitability question based solely on the nature and number of source program statements. If the preliminary analysis suggests a favorable potential for the source program, then the program is subjected to the detailed analysis of the recognizer.