A probabilistic method for calculating hit ratios in direct mapped caches

Abstract

In this paper we present a simple analytical model to predict the hit ratio for a direct mapped cache. The hit ratio is defined as the probability that an arbitrary memory request is satisfied from the cache. A simple analytic expression is obtained for calculating the probability. Address traces obtained when programs are executed on a computer, are used to evaluate the probability. Trace driven simulation is used to show that the analytical model predicts the cache hit ratio to within 10%. The main merit of the proposed model is its simplicity, leading to fast prediction of cache hit ratio.