嵌入式实时系统中抢占控制策略及其优化

任务的抢占在保证了系统可调度性的同时,也带来了必然的抢占开销.而对于资源受限的嵌入式实时系统来说,控制任务的抢占次数,降低抢占引起的资源消耗具有重要的意义.提出了一种基于时间片的抢占控制模型,为每个任务分配一个可抢占次数的上限.由于抢占控制会对系统的可调度性造成影响,因此通过遗传算法对任务的抢占次数上限进行优化,使其在满足任务可调度的前提下取值最小.通过仿真实验,分析了优化算法的性能,并从对任务调度的统计结果中可以看出,采用本文提出的抢占控制策略可以有效地减少任务执行中的抢占次数.

Preemption Control Strategy and Optimization in Embedded Real-Time System

Preemption of tasks guarantees the schedulability of system but,on the other hand,the overheads relevant to preemption ate unavoidable.For the embedded real-time systems of which the resource is constrained,it is important to control the frequency of task preemption so as to reduce the resource consumption due to preemption.A preemption control model based on time slice is therefore proposed to assign every task on upper limit of preemptable frequency.To minimize the upper limit under the constraint on sche...