A Comparison of Locality-Based and Recency-Based Replacement Policies

Caches do not grow in size at the speed of main memory or raw processor performance. Therefore, optimal use of the limited cache resources is of paramount importance to obtain a good system performance. Instead of a recency-based replacement policy (such as, e.g., LRU), we can also make use of a locality-based policy, based on the temporal reuse of data. These replacement policies have usually been constructed to operate in a cache with multiple modules, some of them dedicated to data showing high temporal reuse, and some of them dedicated to data showing low temporal reuse. In this paper, we show how locality-based replacement policies can be adapted to operate in set-associative and skewed-associative [8] caches. In order to understand the benefits of locality-based replacement policies, they are compared to recency-based replacement policies, something that has not been done before.