Device drivers should not do power management

Abstract

We argue that device drivers are not the best place to implement power management policies for components on a system-on-a-chip (SoC). We present empirical evidence that device driver developers are inadequately implementing power management and show the information needed for good power management policies is available outside the device drivers. We implement a software central agent to infer the needed information and accomplish power management without device driver support. We further show that simple hardware support can eliminate the overhead of our approach and extend it to support all SoC components.

Declarative Power Sequencing

“…Closer to our goal of platform power management, for modern servers and phones it is usually the OS's responsibility to implement power management policies -deciding which components to power on or turn off is important to minimize the power requirements. Xu et al argue for a centralized power management agent [46,47] which decides when devices should switch between the discrete enabled or disabled states based on quality-of-service (QoS) requirements and specification of power states. QoS can also be used by agents in embedded systems to automatically find appropriate dynamic power states [16].…”

Automated OS-level Device Runtime Power Management

“…Although sharing the similar goal of device runtime PM with such prior work, we seek to maintain the existing Linux API and are not restricted to a subset of devices. In a previous paper [50], we present a preliminary implementation and the results of the software central PM agent.…”