Operating Systems and Asymmetric Single-ISA CMPs: The Potential for Saving Energy

CPUs consume too much power. Modern complex cores sometimes waste power on functions that are not useful for the code they run. In particular, operating system kernels do not benefit from many power-consuming features that were intended to improve application performance. We propose using asymmetric single-ISA CMPs (ASISA-CMPs), multicore CPUs where all cores execute the same instruction set architecture but have different performance and power characteristics, to avoid wasting power on operating systems code. We describe various design choices for both hardware and software, describe Linux kernel modifications to support ASISA-CMP, and offer some quantified estimates that support our proposal.