In open Store Management Systems(SMS) ,scheduling is very difficult due to the coexistence of hard, soft and non-real-time tasks, the dynamic joining or exiting of tasks, and the uncertainty of task execution time. Thus an improved task scheduling strategy based on server was proposed. The system scheduler consisted of three modules of task acceptance control, scheduling server and adaptive control. The task acceptance control could support tasks to join or exit dynamically without making detailed global schedulability analysis. The scheduling server could support the concurrence of multi-constraint tasks. And the adaptive control could solve the problem resulted from the uncertain task execution time. At last, Constant Bandwidth Server (CBS) algorithm was improved by adding the mechanism of delay task control and spare bandwidth utilization. Simulation showed that the improved algorithm could effectively decrease the deadline missing rate and shorten response time of soft real-time tasks.%针对开放式悬挂物管理系统(Stores Management System,SMS)硬实时、软实时和非实时任务并存,任务需动态加入和退出,且任务执行时间不确定导致的调度困难,提出一种改进的基于服务器的任务调度策略.系统调度器由任务接收控制、调度服务器和自适应控制3大模块组成,其中任务接收控制可在不进行全局可调度性分析的前提下支持任务的动态加入和退出；调度服务器可支持多种约束任务并存于系统；自适应控制可有效解决任务执行时间不确定变化导致的调度困难.最后通过加入延迟任务控制和剩余带宽利用机制改进了常带宽服务器(Constant Bandwidth Server,CBS)算法.仿真实验表明,改进的算法有效地降低了软实时任务的截止期错失率和响应时间.
展开▼
