一个面向嵌入式系统实时性能优化的抢占模型

通过对采用RM调度策略的实时嵌入式系统抢占行为的分析，建立了一个周期性实时任务集的抢占模型，从数学上定量地刻画了因抢占而导致的额外开销与系统中各实时任务属性的关系，以及与整个实时任务集的可调度性的关系。依据该模型并借鉴生物学领域的寄生思想，提出了一个基于进化规划的性能优化方法，通过调整任务启动时间，以减少抢占次数或改变抢占关系，降低系统额外开销，提高系统实时性能；最后通过实验验证了建立在抢占模犁基础上的嵌入式系统件能优化方法的有效件。

Model of preemptive embedded systems for optimizing real-time performance

By analyzing preemptions in embedded real-time systems adopting RM scheduling policy, created a preemption model of periodic real-time tasks. This model described the relationship between overheads incurred by preemptions and the properties of real-time tasks, such as priorities, periods, execution times, deadlines, release times etc. It also showed the relation between the schedulability of the task set and properties of its real-time tasks. Based on the model and taking the idea of parasitism in biology, this paper presented a method of optimizing real-time performance of the embedded systems under the RM scheduling mechanism. This method can reduce preemptions or change the relations of preemptions, decrease overheads to improve real-time performance by adjusting release times of tasks. And then the optimization method underlying the model is evaluated by experiments.