Efficient Runahead Execution: Power-Efficient Memory Latency Tolerance

Overview

Runahead execution improves memory latency tolerance without significantly increasing processor complexity. Unfortunately, a runahead execution processor executes significantly more instructions than a conventional processor, sometimes without providing any performance benefit, which makes it inefficient. This paper identifies the causes of inefficiency in runahead execution and proposes simple -yet effective-techniques to make a runahead processor more efficient, thereby reducing its energy consumption. The proposed efficiency techniques reduce the extra instructions executed in a runahead processor from 26.5% to 6.2% without significantly affecting the 22%performance improvement provided by runahead execution.