Improved indexing for cache miss reduction in embedded systems

The increasing use of microprocessor cores in embedded systems as well as mobile and portable devices creates an opportunity for customizing the cache subsystem for improved performance. In traditional cache design, the index portion of the memory address bus consists of the K least significant bits, where K=log₂(D) and D is the depth of the cache. However, in devices where the application set is known and characterized (e.g., systems that execute a fixed application set) there is an opportunity to improve cache performance by choosing an optimal set of bits used as index into the cache. This technique does not add any overhead in terms of area or delay. We give an efficient heuristic algorithm for selecting K index bits for improved cache performance. We show the feasibility of our algorithm by applying it to a large number of embedded system applications as well as the integer SPEC CPU 2000 benchmarks.