信息物理系统中基于保护阈值的实时调度算法研究

A real-time scheduling algorithm based on protection threshold for CPS

信息物理融合系统CPS是一种融合计算、通信与控制的新型复杂实时分布式系统,系统中计算过程和物理过程在开放环境下持续交互、深度融合。为了对物理世界的信息作出实时反馈,系统一般会采用抢占式调度的方法,保障关键任务能够在截止期前完成。但是,分布式环境中抢占式调度方式容易导致频繁的任务切换,影响系统的实时性。提出了基于保护阈值的调度算法,通过建立保护阈值模型,最大化低优先级任务的执行时间,减少任务切换次数。通过实验验证,算法有效地减少了任务切换次数,提高了CPS系统的实时性能。

CPS is a novel complex real-time distributed system consisting of computing, communication and control ,in which computation process and physical process interacts and integrates in an open environment. In order to respond to the physical world information in real time, the system usually adopts preemptive scheduling methods to guarantee the implementation of crucial tasks before deadline. However,in the distributed environment, preemptive scheduling methods easily lead to frequent task switching, thus affecting the system＇s real-time performance. We propose a real-time scheduling algorithm based on protection threshold to maximize the execution time of low priority tasks by establishing a protection threshold model which can reduce the frequency of task switching. Experimental results show that the proposed algorithm effectively reduces the frequency of task switching, thus improving the real time performance of CPS system.