Minimally-skewed-associative caches

Skewed-associativity is a technique that reduces the miss ratios of CPU caches by applying different indexing functions to each way of an associative cache. Even though it showed impressive hit/miss statistics, the scheme has not been welcomed by the industry, presumably because implementation of the original version is complex and might involve access-time penalties among other costs. This paper presents a simplified, easy to implement variant that we call "minimally-skewed-associativity" (MSkA). We show that MSkA caches, for many cases, should not have penalties in either access time or power consumption when compared to set-associative caches of the same associativity. Hit/miss statistics were obtained by means of trace-driven simulations. Miss ratios are not as good as those for full skewing, but they are still advantageous. Minimal-skewing is thus proposed as a way to improve the hit/miss performance of caches, often without producing access-time delays or increases in power consumption as other techniques do (for example, using higher associativities).