Runahead execution vs. conventional data prefetching in the IBM POWER6 microprocessor

After many years of prefetching research, most commercially available systems support only two types of prefetching: software-directed prefetching and hardware-based prefetchers using simple sequential or stride-based prefetching algorithms. More sophisticated prefetching proposals, despite promises of improved performance, have not been adopted by industry. In this paper, we explore the efficacy of both hardware and software prefetching in the context of an IBM POWER6 commercial server. Using a variety of applications that have been compiled with an aggressively optimizing compiler to use software prefetching when appropriate, we perform the first study of a new runahead prefetching feature adopted by the POWER6 design, evaluating it in isolation and in conjunction with a conventional hardware-based sequential stream prefetcher and compiler-inserted software prefetching. We find that the POWER6 implementation of runahead prefetching is quite effective on many of the memory intensi...

• Type: Conference
• Year: 2010
• Where: ISPASS
• Authors: Harold W. Cain, Priya Nagpurkar
• Keywords: Hardware-based Sequential Stream, ISPASS 2010, POWER6, Software Engineering, Sophisticated Prefetching Proposals