A Case Study in Programming for Parallel-Processors.

An affirmative partial answer is provided to the question of whether it is possible to program parallel-processor computing systems to efficiently decrease execution time for useful problems. Parallel-processor systems ore multiprocessor systems in which several of the processors con simultaneously execute separate tasks of o single job, thus cooperating to decrease the solution time of a computational problem. The processors have independent instruction counters, meaning that each processor executes its own task program relatively independently of the other processors. Communication between cooperating processors is by means of data in storage shared by oil processors. A program for the determination of the distribution of current in an electrical network was written for a parallel-processor computing system, and execution of this program was simulated. The data gathered from simulation runs demonstrate the efficient solution of this problem, typical of a large class of important problems. It is shown that, with proper programming, solution time when N_p processors are applied approaches 1/N_p times the solution time for a single processor, while improper programming con actually lead to an increase of solution time with the number of processors. Storage interference and other measures of performance are discussed. Stability of the method of solution was also investigated. [ABSTRACT FROM AUTHOR]