A Fast and Accurate Approach to Analyze Cache Memory Behavior (Research Note)

The gap between processors and main memory performance increases every year. In order to overcome this problem, cache memories are very useful. Compile-time program transformations can signiicantly improve the performance of the cache. To apply most of these transformations, the compiler requires a precise knowledge of the locality of the diierent sections of the code, both before and after being transformed. Cache Miss Equations (CME) allow to obtain an analytical and precise description of the cache memory behavior for loop-oriented codes. Describing the cache behavior by means of diophantine equations allows us to use mathematical techniques to obtain cache misses. Unfortunately, a direct solution of the CME is com-putationally intractable due to its NP-hard nature. In this work, we propose a fast and accurate approach to estimate the solution of the CME, which is based on the use of sampling techniques. Statistical techniques allow us to approximate the absolute miss ratio of each reference by analyzing a small subset of the iteration space. The size of the subset, and therefore the analysis time, is determined by the accuracy selected by the user. The results show that only a few seconds are required to analyze most of the SPECfp benchmarks with an error smaller than 0.01.