【作者】 孔令君；

【导师】 朱跃龙；

【作者基本信息】 河海大学 ， 计算机应用技术， 2004， 硕士

【摘要】 随着分布式实时系统应用的日益广泛，不同时间约束实时任务并存的情况给系统的调度机制带来了新的需求和挑战；而目前主要的实时中间件的调度模型针对性较强，不适用于这种情况。本文在对实时中间件及相关调度理论进行研究的基础上，对TAO系统的调度服务进行了扩展和改进，实现了一个实时CORBA的集成调度服务模型。在该模型中，对硬实时周期性任务集进行离线调度以满足其可调度性保证：给动态到达的软实时非周期性任务分配一个截止期，提高其响应性能，同时通过在线可调度性分析保证周期性任务的可调度性不受影响；集成调度服务模型在可调度性分析中还考虑了任务之间共享临界区资源的情况，采用优先级上限协议对访问临界区引起的阻塞进行了定界分析。通过区别对待不同时间约束的实时任务，集成调度服务模型将静态的离线调度和动态的在线调度结合了起来，满足了系统中不同类型实时任务的调度需求。 攻硕期间发表学术论文 1．朱跃龙，孔令君，WLAN系统中WEP加密的安全性分析及改进，计算机与现代化，103：70—72，2004更多还原

【Abstract】 As the application of distributed real-time systems is becoming more and more popular, the scheduling mechanism faces new requirements and challenges because of the coexistence of different kinds of time-constraint tasks. To date, available real-time middleware scheduling modals aim at some aspect of scheduling and do not apply to this problem. Based on the research into real-time middleware and relative scheduling theoretic, this thesis implements a Real-Time CORBA Integrated Scheduling Service modal, by extending the scheduling service of TAO. In the Integrated Scheduling Service, hard periodic tasks are scheduled off-line to meet their real-time requirements, and each soft aperiodic task request is assigned a suitable deadline to enhance the aperiodic responsiveness. Scheduling guarantees of hard periodic tasks are preserved through the on-line schedulability analysis. The sharing of critical section resources between the tasks is also considered in the Integrated Scheduling Service’s schedulability analysis, and bounded blocking for accessing the critical section resource is achieved by introducing the Priority Ceiling Protocol. By treating tasks differently according to their time constraints, the static off-line scheduling and the dynamic on-line scheduling are integrated, and the scheduling requirements are satisfied.更多还原