基于优先级表的实时调度算法及其实现

讨论了综合考虑任务的截止期和价值两个特征参数的优先级表设计方法,提出了EDV(earliest deadline value)与VED(value earliest deadline)两种不同的基于优先级表的实时任务调度算法,并且利用多重链表给出了这两种算法的实现,包括任务接收策略与任务完成/夭折策略的算法实现.这种优先级表设计方法及其基于多重链表的实现方法也适用于对任务的其他两种甚至3种不同特征参数之间的综合.基于累积实现价值率、加权截止期保证率与差分截止期保证率3个方面,分析了VED算法与EDV算法的性能,实验结果表明,在所有负载条件下VED算法与EDV算法相对于EDF(earliest deadline first)算法与HVF(highest value first)算法都有很大的性能改进.

A Real-Time Scheduling Algorithm Based on Priority Table and Its Implementation

This paper proposes a new scheduling scheme based on priority table design by integrating two characteristic parameters (i.e. deadline and value) of a task. Two real-time scheduling algorithms from the scheme are presented: earliest deadline value (EDV) and value earliest deadline (VED). Furthermore, how to implement the two algorithms using multi-linked lists is given, including task acceptance policy and task completion/abortion policy. This scheme can also be applied to integrate two other characteristic parameters or even three characteristic parameters of a task. Based on hit value ratio, weighted guarantee ratio and differentiated guarantee ratio, the performance of the VED and EDV algorithms are analyzed, the experimental results show that the VED and EDV algorithms can improve the performance compared to the classical EDF (earliest deadline first) and HVF (highest value first) algorithms under all workload conditions.