Investigating the Use of Cache as a Local Memory

When caches were rst designed, they were very small by today's standards, and the components from which they were constructed were very expensive. For many of today's computer architectures, this is no longer true. Caches have become quite large, some as large as a megabyte, and, there is good reason to question whether the structure of a conventional cache was determined by the size and cost factors that prevailed when they were rst developed. If this is the case, then diierent sorts of structures may be more appropriate for today's caches. Our objective is to obtain a deeper understanding of useful program behavior that can be employed at optimizing program and data layout and to motivate architectural features aimed at selective exploitation of locality. In this paper, we present observations from several prooling experiments to advocate the possibility of fully or partially replacing the cache with a local memory, the local memory being used to house the heavily used references. We also present a memory structure called the SemiCache Architecture, which replaces the cache with a combination of cache and local memory, and present simulation results to prove the feasibility of the scheme.