Distributing a Distributed Problem Solving Network Simulator

Abstract : We describe our experience in improving the real-time performance of a particular large and complex simulator through distributed processing. Our goal was to both reduce the real time required and to increase the scope of the simulations by splitting the existing simulator (written in Lsip) to run on a network of VAX 11/750s connected by DECNet/ETHERNET-II. We present data showing that the additional CPU power and the combined physical memory available in the network contribute to significant real-time speedup. Experience with a two and three machine network indicates that there was no memory contention in a single process simulator, we obtain a speedup proportional to the number of processes. Where there was memory contention in the single process simulator, the speed up is much more dramatic. We also detail the capabilities that were added to the conventional network communication structure to implement, debug, and interact with the distributed simulator.