摘要
在以最早截止期优先算法调度的实时系统中,如果出现新任务插入和/或现行任务加速要求,而系统所剩带宽又不足时,必须进行带宽转让,系统运行模式将被迫发生改变。针对该问题,研究新任务插入和/或现行任务加速的动态过程,分析带宽转让对系统可调度性的影响。应用处理器需求准则,证明截止期丢失只可能出现在某一时间点之前。通过该结论可以合理定义过渡过程的长度,从而展示一个清晰的三阶段模型。最后给出相关仿真实例。
In a real-time system scheduled with the Earliest Deadline First（EDF）algorithm,if the request of new tasks＇ insertion and/or current tasks＇ acceleration occurs and the remaining bandwidth of the system is not enough for this request,then part of the bandwidth has to be freed and the system will change its running mode. Aiming at this problem,this paper discusses the influences on the schedulability by the mode change based on the analysis on the dynamic processes of the insertion of a new task and/or the acceleration of a current task. With the processor demand criterion,it proves that deadline missing is possible only before a time point. Hence the length of the transition can be reasonably defined,and it results a clean research model of three stages. Illustrative examples are also given.
出处
《计算机工程》
CAS
CSCD
2014年第9期55-58,共4页
Computer Engineering
基金
长沙市科技局基金资助项目(K11ZD014-13)
关键词
带宽转让
任务插入
模式改变
过渡过程
截止期
处理器需求准则
最早截止期优先算法
bandwidth transfer
tasks insertion
mode change
transition process
deadline
processor demand criterion
Earliest Deadline First（EDF）algorithm
