Realities associated with parallel processing

At the T. J. Watson Research Center, there is a very active Condensed Matter Physics Group engaged in the study of semiconductors such as silicon (Si) and gallium-arsenide (Ga-As)1. One of the most important computer codes developed at Watson is a Density Functional Program which is used to study the electronic structure of semiconductors. This program also consumes the most CPU time of all other production applications at Watson. Thus, it was decided to undertake the parallelization of this code not only with the hope of reducing elapsed time, improving turnaround on the IBM 30902, and conserving other system resources such as memory and disk space, but also in an attempt to test the IBM Parallel FORTRAN Compiler3 on a production program while developing an understanding of the impact of parallel jobs from a system standpoint. A speedup of 4.4 using 6 processors was achieved for this important scientific production code.