基于时间触发和事件触发的混合实时任务两级调度策略研究

针对混合实时任务应用, 提出一种两级结构调度策略：对周期性实时任务采用时间触发, 非周期性实时任务则采用事件触发．先建立任务模型并定义相关概念, 然后给出调度策略的架构, 并对调度算法、可调度性、抖动、时标间隔及调度策略优化等进行深入研究．结合Windows CE.NET进行了调度策略实验验证, 结果表明, 该方法能提高混合实时任务的确定性, 减小抖动．最后, 讨论了时标间隔与处理器利用率及时标间隔与周期分辨率的关系．

Research on Two-level Hierarchical Scheduling Scheme of Hybrid Real-Time Tasks Based on Time-Triggered and Event-Triggered

For the application of hybrid real-time tasks(HRTT), a two-level hierarchical scheduling scheme is presented, namely, the time-triggered mode and event-triggered mode are adopted for the periodic real-time tasks and aperiodic real-time tasks respectively. First, the task model is established and the related concepts are defined. Then, the structure of scheduling scheme is proposed, and some crucial technologies such as scheduling algorithm, schedulability, jitter, tick-interval and optimal scheduling scheme are deeply researched. Subsequently, combined with Windows CE.NET, the experiment validation of scheduling scheme is carried out and the results demonstrate that the method can improve the determinatation of HRTT and reduce jitter. Finally, the relation between tick-interval and CPU utilization, and that between tick-interval and period resolution are discussed.