Decelerating Suspend and Resume in Operating Systems

Short-lived tasks have a large impact on mobile computer's battery life. In executing such tasks, the whole system transitions in and out of the deep sleep mode. This suspend/resume procedure is controlled by the operating system (OS), which consumes a dominating portion of energy. Through characterizing the Linux kernel on a variety of modern system-on-chips (SoCs), we show that the OS suspend/resume mechanism is fundamentally slowed down by various IO devices, which frequently keep CPU waiting. To minimize energy consumption, we advocate offloading the OS suspend/resume to a miniature processor that waits more efficiently. To this end, we propose a new virtual executor that runs on a miniature core and directly executes the unmodified kernel binary of the main CPU. We construct the virtual executor centering on software-only, cross-ISA binary translation, an approach previously considered prohibitively expensive. Through novel designs and optimizations, we reduce the translation overhead by 5×. The preliminary benchmarks show promising energy efficiency.