Power reduction through work reuse [superscalar processor microarchitecture]

Power consumption has become one of the big challenges in designing high performance processors. The rapid increase in complexity and speed that comes with each new CPU generation causes greater problems with power consumption and heat dissipation. Traditionally, these concerns are addressed through semiconductor technology improvements such as voltage reduction and technology scaling. This work proposes an alternative solution to this problem, by dealing with the power consumption in the very early stage of the microarchitecture design. More precisely, we show that by modifying the well-established out-of-order, superscalar processor architecture, significant gains can be achieved in terms of power requirements without performance penalty. Our proposed approach relies on reusing as much as possible from the work done by the front-end of a typical pipelined, superscalar out-of-order via the use of a cache nested deeply into the processor structure. Experimental results show up to 52% (20% on average) savings in average energy per committed instruction for two different pipeline structures.