Energy-aware sporadic tasks scheduling with shared resources in hard real-time systems

We address the problem of minimizing overall energy consumption for sporadic tasks with shared resources in a real time system. Previous algorithms use the static speed to deal with this problem. However, we have proposed a novel scheduling algorithm, called DSSTS, for the sporadic tasks with shared resources. The DSSTS algorithm schedules the task at the dynamic low speed and the task switches to the high speed when it is blocked by another lower priority task. It assumes that each task is executed with its worst case execution time. For energy efficiency, we have proposed a dynamic reclaiming dynamic speed sporadic tasks scheduling algorithm, called DRDSSTS. The DRDSSTS algorithm is an extension of the DSSTS algorithm. It can reclaim the dynamic slack time generated from the early completion task to adjust to the processor speed. Moreover, it can use the DPM technique to put the processor into a dormant mode to save energy when the processor is in an idle mode. The experimental results show that the DRDSSTS algorithm can reduce the energy consumption up to 2.64%-37.16% over the DSSTS algorithm and it consumes 35.16%-71.15% less energy than that of the DS algorithm.