StarT-NG: Delivering seamless parallel computing

Abstract

START-NG is a joint MIT-Motorola project to build a highperformance message passing machine from commercial systems. Each site of the machine consists of a PowerPC 620-based Motorola symmetric multiprocessor (SMP) running the AIX 4.1 operating system. Every processor is connected to a low-latency, high-bandwidth network that is directly accessible from user-level code. In addition to fast message passing capabilities, the machine has experimental support for cachecoherent shared memory across sites. When the machine requires memory to be kept globally coherent, one processor on each site is devoted to supporting shared memory. When globally coherent shared memory is not required, that processor can be used for normal computation tasks. START-NG will be delivered at about the time the base SMP is introduced into the marketplace. The ability to be both a collection of standard SMP and an aggressive message passing machine with coherent shared memory makes START-NG a good building block for incrementally expandable parallel machines.