Application-Guided Power Gating Reducing Register File Static Power

Power and energy efficiency are on the top priority list in embedded computing. Embedded processors taped out in deep submicron technology have a high contribution of static power to overall power consumption. At the same time, current embedded processors often include a large register file (RF) to increase performance. However, a larger RF aggravates the static power issues associated with technology shrinking. Therefore, approaches to improve static power consumption of large RFs are in high demand. In this paper, we introduce an application-guided function-level register file power-gating (AFReP) approach to efficiently manage and reduce the RF's static power consumption. The AFReP is an interplay of automatic binary analysis and instrumentation at function-level granularity supported by instruction-set architecture and microarchitecture extensions. The AFReP enables runtime power-gating of registers during unutilized periods, whereas applications can fully benefit from a large RF during utilized periods. To demonstrate the AFReP's potential for reducing static power consumption, we have enhanced a Blackfin processor with the AFReP technology. Using the AFReP, the RF static power is reduced on average by 64% and 39% for control and DSP applications, respectively. At the same time, the AFReP only induces a very minimal overhead of 0.4% and 0.6%.