Performance analysis of tightly-coupled multiprocessor minicomputers

The design of a multiprocessor computer system requires the solution of architectural problems, related both to the design of the machine and to the operating system, which are not found in monoprocessor systems. Moreover, to achieve the expected level of performance, an accurate balance between the CPU and the I/O subsystem is very important. In this paper models for evaluating the performance of tightly-coupled symmetric multiprocessor minicomputers which consider both CPU and I/O processing are proposed. These models have been validated by a set of results obtained from benchmarks executed on a system which can contain up to 3 Motorola MC68020 CPUs, running a multiprocessor version of the 4.2 BSD UNIX1 operating system. Some general criteria, derived from both the developed model and from actual experimentations, are proposed and some suggestions are given for predicting the performance of such systems.