Dynamically adaptive register file architecture for energy reduction in embedded processors

Energy reduction in embedded processors is a must since most embedded systems run on batteries and processor energy reduction helps increase usage time before needing a recharge. Register files are among the most power consuming parts of a processor core. Register file power consumption mainly depends on its size (height as well as width), especially in newer technologies where leakage power is increasing. We provide a register file architecture that, depending on the application behavior, dynamically (i) adapts the width of individual registers, and (ii) puts partitions of temporarily unused registers into low-power mode, so as to save both static and dynamic power. We show that our scheme increases register file area by 3.6% and imposes 2.85% performance overhead on average. Our experimental results on OpenRISC 1200 processor and with selected MiBench benchmark suite show up to 29%, and 54% (24% and 49% on average) reduction in dynamic and static energy consumption of the register file, respectively.