Enhancements for Accurate and Timely Streaming Prefetcher

In this paper, we describe several enhancement techniques to improve the state-of-the-art stream prefetcher. First, the enhanced stream prefetcher takes streams with long stride into consideration to avoid wasteful prefetches. Second, accessing a node in a tree or graph structure may have a different direction than the traversal direction through the structure. The enhanced stream prefetcher eliminates this type of noise for establishing the stream. Third, regular streams for array accesses are often repeated. Initiating penalty can be avoided by early re-establishing a repeated stream. Fourth, an established stream may be dead before being removed from the stream prefetching table. A dead stream removal scheme reduces inaccurate prefetches. Performance evaluations based on SPEC applications show that the enhanced stream prefetcher improves 38%, 42%, and 55% of CPI for the three tested cache configurations provided by the 1 JILP Data Prefetching Championship Committee [19] with respect to the base design without prefetching. In comparison with the original stream prefetcher, the improvements are 2%, 18%, and 19% respectively.