OCP: Offload Co-Processor for energy efficiency in embedded mobile systems

Jie Tang, Chen Liu, Yu-Liang Chou, Shaoshan Liu

Abstract: In current embedded mobile systems design, the application processor (AP) is often woken up to service interrupts and user requests. However, this kind of wakeups from sleep is very expensive in terms of battery usage. In the observation that the operating system/driver workloads are very light-weight, in this paper we propose the Offload Co-Processor (OCP) SoC architecture. In the OCP SoC design, when the device is idle, we offload the operating system workloads (mainly interrupt handling workloads) to an ultra-low-power coprocessor. This way, the co-processor would be able to handle most wake-up requests without awakening the heavy-weight AP, thus avoiding the overhead of AP spin-up/down. Using GPS continuous sampling workload as a case study, we show that the proposed OCP SoC design would extend battery life by 3.5 folds.