一种采用抢占阈值的软实时动态调度策略PT-STDS  

Dynamic Scheduling Strategy PT-STDS Based on Preemption Threshold of Soft Real-time

作　　者：王文乐[1] 龚俊[1] 曹重华[2] 曹远龙 陈洪琪 柯胜男[1] 涂珍 WANG Wen-le;GONG Jun;CAO Zhong-hua;CAO Yuan-long;CHEN Hong-qi;KE Sheng-nan;TU Zhen(School of Software, Jiangxi Normal University, Nanchang 330022, China;School of Software and Communication Engineering, Jiangxi University of Finance ＆ Economics, Nanchang 330032, China;School of Mathematics ＆ Computer Science, Jiangxi Science ＆ Technology Normal University, Nanchang 330038, China)

机构地区：[1]江西师范大学软件学院,南昌330022 [2]江西财经大学软件与通信工程学院,南昌330032 [3]江西科技师范大学数学与计算机科学学院,南昌330038

出　　处：《小型微型计算机系统》2018年第5期986-990,共5页Journal of Chinese Computer Systems

基　　金：国家自然科学基金项目(61562044;41661083)资助;江西省自然科学基金项目(20161BAB212046)资助;江西省教育厅科学技术研究项目(GJJ150319;GJJ160331;GJJ160781和GJJ170234)资助;江西师范大学校级项目(5462和7194)资助

摘　　要：抢占式实时任务调度,其任意抢占会浪费系统资源而影响调度性能;有必要尽量减少任务间的无效抢占.针对软实时任务的特点,提出一种基于抢占阈值的动态调度策略PT-STDS.首先,PT-STDS策略考虑软实时任务的空闲时间和价值密度,提出综合两者的优先级构造函数.其次,PT-STDS策略根据任务的响应时间和任务间的抢占关系,确定任务的抢占阈值.通过设置任务抢占阈值减少较低优先级任务被抢占的机率,以提高整个系统任务间的有效抢占和执行完成率.实验证明,在软实时系统环境下,PT-STDS策略能够有效提高任务成功率、减少软实时任务的延迟时间,并提高系统总收益.The arbitrarily preemption of preemptive real-time task scheduling can waste system resources and affect scheduling performance.It is necessary to minimize the ineffective preemption between tasks. Based on the characteristics of soft real-time task,a dynamic scheduling with preemption threshold strategy PT-STDS is proposed in the paper. Firstly,considering the slack time and value density,the priority assignment method is included in the PT-STDS. Furthermore,by calculating task＇ s response time and analyzing preemption relationship,the preemption thresholds is assigned. By setting the task＇s preemption threshold,reducing the probability of low priority tasks to be preempted,improving the effective preemption and completion rate of tasks. Simulation results show that in the soft real-time system environment,the PT-STDS strategy can improve the success rate of the task,reduce the delay time of the soft realtime task,and increase the total revenue of the system.

关 键 词：软实时 抢占阈值 动态优先级 任务调度 

分 类 号：TP393[自动化与计算机技术—计算机应用技术]