Predictor-directed stream buffers

Abstract

An effective method for reducing the effect of load la- tency in modern processors is data prefetching. One form of data prefetching, stream buffers, has been shown to be par- ticularly effective due to its' ability to detect data streams and run ahead of them, prefetching as it goes. Unfortu- nately, in the past, the applicability of streaming was limited to stride intensive code. In this paper we propose Predictor-Directed Stream Buffers (PSB), a scheme in which the stream buffer follows an address prediction stream instead of a fixed stride. In addition, we examine using confidence techniques to guide the allocation and prioritization of stream buffers and their prefetch requests. Our results show for pointer-based appli- cations that PSB provides a 30% speedup on ave rage over no prefetching, and provides an ave rage 10% speedup over using previously proposed stride-based stream buffers for pointer-intensive applications.