Operating-System Aided Power-aware Policy for Embedded Peripheral Device

This paper presents a new framework for power reduction in embedded system by monitoring the system load and rescheduling the requests for devices. It focuses on the device that has different working states and when being idle, can be set into a power-down state. We use an "Up-Down" method to join the process, which initiates the requests to devices, Transferring Module and devices together. So the requirements specific to every request will be more detailed to power manager to make a decision. The request specific information is calculated in statistical method, which insures the accuracy. Transitions between different states of the device are achieved by breaking an accumulation threshold which evolves from the request specific information mentioned above. Using this framework, running period will be more intensive and there are longer idle period, devices do not have to change states frequently. Because the action of changing states is power consuming, the framework can get obvious reduction in power consumption. We implement this framework on an Intel XScale® PXA255 Development Board and on average it can save more than 20% power compared to other power-aware policies.