计算机工程
計算機工程
계산궤공정
COMPUTER ENGINEERING
2014年
9期
55-58
,共4页
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
帶寬轉讓%任務插入%模式改變%過渡過程%截止期%處理器需求準則%最早截止期優先算法
대관전양%임무삽입%모식개변%과도과정%절지기%처리기수구준칙%최조절지기우선산법
bandwidth transfer%tasks insertion%mode change%transition process%deadline%processor demand criterion%Earliest Deadline First( EDF) algorithm
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。
在以最早截止期優先算法調度的實時繫統中,如果齣現新任務插入和/或現行任務加速要求,而繫統所剩帶寬又不足時,必鬚進行帶寬轉讓,繫統運行模式將被迫髮生改變。針對該問題,研究新任務插入和/或現行任務加速的動態過程,分析帶寬轉讓對繫統可調度性的影響。應用處理器需求準則,證明截止期丟失隻可能齣現在某一時間點之前。通過該結論可以閤理定義過渡過程的長度,從而展示一箇清晰的三階段模型。最後給齣相關倣真實例。
재이최조절지기우선산법조도적실시계통중,여과출현신임무삽입화/혹현행임무가속요구,이계통소잉대관우불족시,필수진행대관전양,계통운행모식장피박발생개변。침대해문제,연구신임무삽입화/혹현행임무가속적동태과정,분석대관전양대계통가조도성적영향。응용처리기수구준칙,증명절지기주실지가능출현재모일시간점지전。통과해결론가이합리정의과도과정적장도,종이전시일개청석적삼계단모형。최후급출상관방진실례。
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.