Multiple stream tracker: a new hardware stride prefetcher

Data prefetching is a very important technique for hiding memory latency and improving performance in modern computer processors. Existing techniques are not able to find all or best data streams to prefetch. This paper proposes a new prefetching technique, Multiple Stream Tracker (MST), that improves over state-of-the-art by identifying strided accesses in a cache miss stream. Targeting the lower levels of cache it searches for the best among all possible strided streams to prefetch. A technique to efficiently search and rank multiple strided streams is proposed. The proposed technique can identify streams that subsume streams generated by both delta correlated and standard stride prefetchers. The MST pefetcher can also significantly improve performance in parallel programs. The Multiple Stream Tracker applied at the L3 cache improves the IPC by up to 173% (14% on average) over stride prefetching for SPEC CPU2006 benchmarks. The improvement is up to 92% over delta correlation (5% on average). The speedup for SPEComp programs is up to 300% over delta correlation (22% on average). MST also has lower average memory bandwidth requirements compared to prior techniques.