Current and anticipated advances in semiconductor technology, in general, and in the area of microcomputers, in particular, will lead to a widespread utilization of distributed computer systems. The advantages of these types of systems have led to numerous design efforts. Most of these efforts have been undertaken in a largely ad hoc manner without any mechanism for the evaluation of design tradeoffs. At the same time it has become apparent that the most desirable evaluation approach must be objective and quantitative in nature. In this document we present a framework by means of which such an evaluation can be undertaken. The elements of the framework are identified and the requirements of each of these elements are given.

The overhead involved in the real-time multiprocessor execution of parallel-processable segments of a sequential program is investigated. The execution follows a preprocessing phase in which the source program is analyzed and the parallel-processable segments are recognized. A number of representations of a parallel-processable program are possible. A table representation is used, and a technique is developed to efficiently interpret this table in a system in which a number of identical processors share a common memory.

This paper describes a set of techniques that can be used to optimally schedule a sequence of interrelated computational tasks on a multiprocessor computer system. Using a directed graph model to represent a computational process, two basic problems are solved here. First, given a set of computational tasks and the relationships between them, the tasks are scheduled such that the total execution time is minimized, and the minimum number of processors required to realize this schedule is obtained. The second problem is of a more general nature. Given k processors, the tasks are scheduled such that execution time is again minimized. Consideration is given to tasks of equal and unequal duration, and task preemption is not allowed.

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.