A Powerful New Programming Model for Parallel Computation

Abstract

If a looping construct has the property that no iteration of the loop requires for its execution a result from a previous iteration, correct results can be obtained by executing all of the loop iterations simultaneously on different processors.

At Myrias Research Corporation, a virtual machine has been designed, and is being implemented, on which such parallel execution of loop constructs is achieved by replacing the looping instruction (“do” in ANSI Fortran 77) with a modified instruction (“par do” in Myrias Parallel Fortran — MPF). Each loop iteration executes in its own, separate memory space, and these memory spaces are automatically merged when all of the tasks have completed. The architecture of the Myrias parallel computer is described briefly.

We describe a new memory model which utilizes local, distributed memory, and allows for the dynamic reconfiguration of parallel tasks at the operating system level. Such a model gives rise to a powerful new parallel programming method. Further, we describe how recursive parallel methods (RPM) can be used effectively. The three main language extensions are orthogonal, and their combination provides easy access to flexible, high order, adaptive algorithms. Algorithmic examples of the application of this programming model are demonstrated.

This paper has been left virtually unchanged from its original version written in 1985. Since then, Myrias Research Corporation has developed a working prototype encompassing many of the features discussed herein, and is presently completing an advanced, commercially available, parallel system.