Research Of A Power-aware Real-time Scheduling Algorithm

With the rapid development of electronic devices, embedded products are widely-used. Embedded systems are more and more complicated, and the increase of the energy consumption restricts the development of embedded systems. So, reducing power consumption and saving energy become an important research direction in embedded systems.Many modern embedded processors at least have three operating modes:active mode, idle mode and sleep mode. A processor consumes much less energy in the sleep mode than that in other two modes. Rowe proposed an Energy Saving RateHarmonized Scheduling algorithm for energy saving which is based on rate monotonic algorithm and adding a virtual sleep task, through clustering task execution and lumping idle duration, and the processor only needs to support two modes and saving energy. However, the author didn't take into account of the energy consumptions of switching modes, the Energy Saving RateHarmonized Scheduling algorithm is not realistic.This paper improves and extends the ESRHS algorithm. First, we analyse the reasons of the pessimism of the pessimism test of ESRHS algorithm and propose a new schedulabilty test which can reduce the pessimism. And then we improve the ESRHS algorithm. Thinking of the overhead of switching modes, we propose a better algorithm than ESRHS algorithm which can reduce the numbers of switching modes and saving energy. Third, we expand the ESRHS algorithm and propose another effect dynamic energysaving scheduling algorithm which can process a long execution time of sleep task and save more energy. So the algorithm we proposed in this paper is fit for more types of the CPU. At last we do plenty of simulation and the results indicate that our algorithm can save more power consumption by 17%-65%.