Power-saving Technology Combining DVS And EDF

Along with the increasingly high demand of performance in embedded devices, energy problem become a key issue constrain the development of it. Low-power design has become the hotspot of embedded system both on hardware and software design. This paper focuses on software energy-saving technology.DVS technology is an energy-saving technology which dynamic change the voltage and frequency of the device. EDF is a real-time task scheduling model. DVS don't consider the energy consumption both of processor and memory. EDF can not get a good power-saving result in the periodic task sets where task dependency exists.In the DVS model which is presented in this paper, we get the information of cache and instruction-executed, and choose the optimum operating state according to the pre-set data comparison table, thereby reducing the energy consumption of processor and memory.As the embedded system is the extensive use periodic task, this paper reconstructs the EDF model through combining the DVS and original EDF, obtain task dependency graph, schedule task priority, insert DVS operation, and consider the situation where the task set share a final deadline and the situation where tasks have different deadlines.In this paper, we use EMH255 which uses Intel PXA255 processor as our experimental platform. If the change of memory operation time between adjacent time unit is in the range of 5%, our DVS power-saving model can reach 8% of the energy saving effect. In our EDF model, processor energy consumption can reach 8.52% of the energy saving effect when more than 30% tasks can be inserted DVS operating. In short, the paper realizes the DVS technology and reconstructs EDF model, implements the purpose of power saving.