一个基于RM的弱硬实时调度算法

在定义弱硬实时系统周期任务模型的基础上,提出基于RM调度策略的弱硬实时调度算法PV-RM.PV-RM调度算法在对任务的未来行为进行预测的基础上,通过将任务在抢占段和让步段之间切换,动态调整任务的优先级以反映紧迫程度.在系统过载时,PV-RM调度算法按照任务的初始优先级,为重要的任务提供满足其弱硬实时约束的服务,为其他任务提供尽力而为的服务.给出了PV-RM调度算法的可调度性分析及可调度判定不等式,并通过示例分析说明了该算法的有效性.

A Weakly Hard Real-Time Scheduling Algorithm Based on RM

Defining the periodic task model for weakly hard system,the PV-RM scheduling algorithm is presented on the basis of RM scheduling policy.By virtue of predicting the future tasks,PV-RM can adjust dynamically the priority of task by switching over its running state between P segment and Y segment in accordance to urgency.Once the tasks overload the system,PV-RM will provide the more important tasks having higher initial priority with the service to satisfy their weakly hard real-time restriction,and provide best-effort service to other tasks having lower initial priority.Schedulability analysis and schedulable judging inequation of the PV-RM are also presented,and the validity of the algorithm is illuminated by analyzing examples.