ISSN 1000-1239 CN 11-1777/TP

计算机研究与发展 ›› 2017, Vol. 54 ›› Issue (1): 184-191.doi: 10.7544/issn1000-1239.2017.20150890

• 系统结构 • 上一篇    下一篇

事件触发关键级提升的实时任务可调度性分析

黄丽达,李仁发   

  1. (湖南大学信息科学与工程学院 长沙 410082) (hld_jt@hnu.edu.cn)
  • 出版日期: 2017-01-01
  • 基金资助: 
    国家自然科学基金项目(61173036) This work was supported by the National Natural Science Foundation of China (61173036).

The Schedulable Analysis of Real-Time Tasks After Event-Triggered Criticality Level Transition

Huang Lida, Li Renfa   

  1. (College of Computer Science and Electronic Engineering, Hunan University, Changsha 410082)
  • Online: 2017-01-01

摘要: 混合关键级(mixed criticality, MC)系统能够同时保证高效地资源利用与高关键任务的正确执行.当前,对混合关键级系统的研究多认为,从低关键级提升到高关键级的时机是高关键级任务执行超过其低关键级模式下时间预算的时刻.但在实际应用的嵌入式系统中,关键级模式的提升是由诸如所处环境变化、控制切换等系统外部事件触发的,即关键级的提升可能发生在任务执行过程中的任何时刻.在单处理器平台上,针对使用固定优先级调度策略的周期任务集,当外部事件触发关键级提升后,基于响应时间分析得出了可调度高关键级任务的必要条件;并对关键级提升后,高关键级任务可能通过优先级交换满足截止时限的条件进行了分析,得出了相应的优先级交换算法.仿真实验验证了事件触发关键级提升时高关键级任务的可调度性及优先级交换算法的有效性.

关键词: 关键级, 事件触发, 优先级, 响应时间, 截止时限

Abstract: Both effective resource utilization and meeting the deadlines of high-criticality tasks are objectives of mixed-criticality systems. Currently, it is considered the moment that any of high-criticality tasks execute for their low-critical worst case execution time without completing the system switch from low to high-criticality mode immediately. However, in real embedded applications, the increasing criticality is event-triggered which includes outer circumstance changing, control switching, and so on. That is why the time of raising criticality level can be occurred before, during, or after a task implementation. In this paper we center on that the time of event-triggered increasing criticality is how to influent the scheduling of high-criticality and fixed priority periodic tasks, which is based on the response time analysis. A sufficient condition of scheduling high criticality tasks is derived. Then we discuss when and how to exchange priorities between two high-critical tasks in order to meet their deadlines at the same time, and propose an algorithm of exchanging priorities. Evaluations illustrate the benefits of the schedulable condition and the priority exchanging algorithm.

Key words: criticality, event-trigger, priority, response time, deadline

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