Abstract:

When the computation demand of (some of) the higher critical tasks increase, current mixedcriticality scheduler discards less critical tasks in order to guarantee that the higher critical tasks can occupy enough processor time for normal execution. Considering the data consistency and integrity and the corresponding performance loss, the above method for discarding the lower critical tasks arbitrarily is very passive. On the other hand, the real computing time of tasks cannot always reach the execution time under their worst case, and the scheduling has enough time slacks in multiprocessors platform. Hence lowcritical tasks should and could be handled in a more positive way. On homogenous multiprocessors platform, two kinds of queues are built up. One stores the reclaimed time slacks, while the other stores tasks including the ready tasks and the discarded low critical tasks. According to the characteristics of the ready tasks and the discarded low critical tasks, two kinds of scheduling are adopted: mixedcriticality local scheduling for the ready tasks, and the allocated time slacks for the discarded low critical tasks. Simulation experimental results show that, our method can guarantee the deadline of the higher critical tasks and increase acceptable ratio of tasks obviously.

Key words: Mixed criticality;scheduling;multiprocessors;task queue;dynamic slack reclamation