面向信息物理系统的时间不确定任务流动态实时调度算法

Dynamic Real-time Scheduling Algorithm with Uncertain-time Task Flow for Cyber-physical System

信息物理系统(cyber-physical system,CPS)需要提供软件和硬件的无缝协调,满足系统的动态响应需求,实时任务准确的调度对CPS至关重要.事实上,由于各种原因,任务发生时间往往是不确定的.针对CPS时间不确定性导致的无法确定任务调度顺序的问题,首先利用剪枝简化发生时间不确定任务流,对所有简化后的任务流组合序列求解执行概率,确定任务流初始执行顺序;然后根据任务截止时间和空闲时间分派任务优先级;最后基于任务流初始执行顺序结合任务优先级,提出了一种动态优先级的面向CPS时间不确定任务流抢占调度算法.仿真实验结果证明,该算法能较地好保证系统调度任务的准确性和系统执行效率.

Cyber-physical system（ CPS） needs to provide seamless coordination of software and hardware to meet the dynamic response requirements of the system. Indeed,accurate scheduling of real-time tasks is critical to CPS. However,the time of the task is uncertain because of a variety of reasons,causing uncertainty on the time tasks in the CPS. First,we simplified the uncertain-time task flow by using the pruning algorithm; then,we determined the execution probability of all the simplified task flow combination sequences,and we provided the initial task flow execution order. Then,we proposed a dynamic priority scheduling algorithm for uncertain-time task flow on CPS,which take into account the task deadline and idle time dispatching task priority and is based on the initial execution sequence of task flow combined with the task priority. The experimental results show that the algorithm can guarantee a better accuracy of the system scheduling tasks and the system execution efficiency.