Spectrum of choices: Superpipelined, superscalar, or multiprocessor?

Abstract

An analytical model is proposed as an alternative tool for analyzing the tradeoff between superpipelined processors, superscalar processors, and multiprocessors. The duality of superpipelines and superscalars is examined in detail. Combined systems, such as superpipelined multiprocessors and superscalar multiprocessors, are also analyzed. The model shows that the number of pipelines (or processors) at which the maximum throughput is obtained is increasingly sensitive to this ratio as the memory access time increases. Further, as a function of inter-iteration dependency distance, optimum throughput is shown to vary nonlinearly, whereas the corresponding optimum number of processors varies linearly. The predictions from the analytical model agree with similar results published using simulation-based techniques.