Reducing Conflict Misses by Application-Specific Reconfigurable Indexing

The predictability of memory access patterns in embedded systems can be successfully exploited to devise effective application-specific cache optimizations. In this paper, an improved indexing scheme for direct-mapped caches, which drastically reduces the number of conflict misses by using application-specific information, is proposed. The indexing scheme is based on the selection of a subset of the address bits. With respect to similar approaches, the solution has two main strengths. First, owing to an analytical model for the conflict-miss conditions of a given trace, it provides a symbolic algorithm to compute the optimum solution (i.e., the subset of address bits to be used as cache index that minimize the number of conflict misses). Second, owing to a reconfigurable bit selector that can be programmed at run time, it allows the optimal cache indexing to fit to a given application. Results show an average reduction of conflict misses of 24%, measured over a set of standard benchmarks, and for different cache configurations.