A quantitative evaluation of cache types

The authors classify caches according to both index and tag. Since both index and tag could be either virtual or real, the classification results in four combinations or cache types. The real address caches with virtual tags under investigation are prediction-based, since index bins are generated from a small array and predictions could be false. As a result, the authors also discuss and evaluate real address most recently used (MRU) caches with real tags, and propose a new cache structure, virtually indexed MRU caches with real tags. Each of the four cache types and MRU caches are discussed and were evaluated using trace-driven simulation.