Real-Time Task Limited Preemptive Scheduling on Multi-processors

In multi-processors scheduling,fully preemptive scheduling (F-PS) may result in the tasks with lower priority beyond the deadline.In this work,two limited preemptive scheduling (LPS) algorithms are proposed to solve the above problem.The first one is regular deferrable scheduling (RDS),in which the tasks with higher priority preempt the first among the lower priority tasks that finish executing a non-preemptive region.The other is adaptive deferrable scheduling (ADS),where the scheduler waits to preempt the lowest priority running task.A series of experiments are carried out via the built simulator to investigate the performance of the two LPS,which show:(1) the number of preemptions in dynamic and static scheduling is F-PS > RDS >ADS;(2) the schedulable ratios of RDS and ADS are almost equal to the one of F-PS when the time consuming in preemptions is bigger that the threshold.