用双优先级算法调度控制系统的实时周期性任务  

Scheduling real-time periodic task of control system with dual priority algorithm

作　　者：刘怀[1] 沈捷[1] 费树岷[1] 

机构地区：[1]东南大学自动化研究所

出　　处：《东南大学学报（自然科学版）》2003年第2期190-193,共4页Journal of Southeast University：Natural Science Edition

基　　金：国家攀登计划资助项目 ( 970 2 110 17);国家自然科学基金资助项目 ( 6993 40 10 ) .

摘　　要：根据控制系统中存在强实时周期任务和软实时周期任务的特点 ,采用双优先级算法进行任务调度 .该算法将优先级带宽分为 3部分 :高带优先级、中带优先级和低带优先级 .强实时任务实例到达后先将其优先级设置在低带 ,经过一段时间若还没有完成 ,则将其优先级提升到高带 ,软实时任务的优先级设置在中带中 ,从而控制任务的执行 .文章研究了强实时任务优先级提升时间的存在性 ,给出了求取优化的优先级提升时间的算法 .在软实时任务满足一定丢失率 ( 0≤βsi<1 )的条件下分析任务集的可调度性 。Since the real-time sets in control system consist of hard real-time periodic tasks and soft real-time period tasks, the dual priority algorithm is adopted for scheduling these tasks. The algorithm divides priority band into three parts, i.e. high priority band, middle priority band and low priority band. The priority of hard real-time task is set in low priority when its instance arrives and it is promoted into high priority band after a period of time. The priority of soft real-time task is set in middle priority band. The existence of the priority promotion time of hard real-time task is investigated. The method for computing the optimal priority promotion time of hard real-time task is presented. Under the condition that the lost ratio of the soft real-time task's instances βsi is in certain value (0&leβsi<1), the schedulability of tasks is analyzed. The result of simulation shows that the scheduling algorithm is effective.

关 键 词：双优先级算法 任务调度控制系统 强实时周期任务 软实时周期任务 

分 类 号：TP273[自动化与计算机技术—检测技术与自动化装置] TP31[自动化与计算机技术—控制科学与工程]