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

Content Provider	IEEE Xplore Digital Library
Author	Cain, H.W. Nagpurkar, P.
Copyright Year	2010
Description	Author affiliation: IBM T.J. Watson Research Center, Yorktown Heights, NY, USA (Cain, H.W.; Nagpurkar, P.)
Abstract	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 intensive applications studied; in isolation it improves performance as much as 36% and on average 10%. However, it outperforms the hardware-based stream prefetcher on only two of the benchmarks studied, and in those by a small margin. When used in conjunction with the conventional prefetching mechanisms, the runahead feature adds an additional 6% on average, and 39% in the best case (GemsFDTD).
Starting Page	203
Ending Page	212
File Size	313424
Page Count	10
File Format	PDF
ISBN	9781424460236
e-ISBN	9781424460243
DOI	10.1109/ISPASS.2010.5452021
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2010-03-28
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Prefetching Microprocessors Hardware Application software Software performance Context modeling Java Proposals Optimizing compilers Performance evaluation
Content Type	Text
Resource Type	Article

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