Runtime identification of microprocessor energy saving opportunities

High power consumption and low energy efficiency have become significant impediments to future performance improvements in modern microprocessors. This paper contributes to the solution of these problems by presenting: linear regression models for power consumption and a detailed study of energy efficiency in a modern out-of-order superscalar microprocessor. These simple (2-input) yet accurate (2.6% error) models provide a valuable tool for identifying opportunities to apply power saving techniques such as clock throttling and dynamic voltage scaling (DVS). Also, future work in improving energy efficiency is motivated by a detailed analysis of SPEC CPU 2000 workloads. The vast majority of workloads are found to yield very low energy efficiency due to the frequency of level two (L2) cache misses and misspeculated instructions.