A two-level hierarchical scheduling scheme for hybrid tasks in priority-based preemptive systems

For the application of hybrid tasks in priority-based preemptive systems, an innovative two-level hierarchical scheduling scheme is presented, and the time-triggered mode and event-triggered mode are adopted for the periodic real-time tasks and aperiodic real-time tasks respectively. First, the scheduling structure is proposed and the related concepts are defined. Then, the task model is established, and some crucial technologies such as scheduling algorithm, schedulability and jitter control are deeply researched. Subsequently, combined with Windows CE.NET, the experiment validation of scheduling scheme is carried out and the results demonstrate that the method can improve the determination of real-time tasks and reduce jitter. Specially, the jitter can be even eliminated if the task periods and tick-interval are rational. Finally, the choice of tick-interval is discussed. So the proposed scheduling scheme is efficient for hybrid tasks.