Tradeoffs in the Design of Single Chip Multiprocessors

: By the end of the decade, as VLSI integration levels continue to increase, building a multiprocessor system on a single chip will become feasible. In this paper, we propose to analyze the tradeoffs involved in designing such a chip, and specifically address whether to allocate available chip area to larger caches or to large numbers of processors. Using the dimensions of the Alpha 21064 microprocessor as a basis, we determine several candidate configurations which vary in cache size and number of processors, and evaluate them in terms of both processing power and cycle time. We then investigate fine tuning the architecture in order to further improve performance, by trading off the number of processors for a larger TLB size. Our results show that for a coarse-grain execution environment, adding processors at the expense of cache size improves performance up to a point. We then show that increasing TLB size at the expense of the number of processors can further improve performance. K..