HLA/RTI下周期与非周期任务调度的实时性改进

为了把高层体系结构的标准应用到实时系统中，必须确保运行时支撑环境的实时性.联邦成员间相关的任务之间有优先顺序约束关系，在联邦成员内调度运行时较难提供可预测的响应，因而难以保证所有任务尤其是非周期任务的实时性.以任务调度理论的角度在联邦成员内部综合调度周期与非周期任务运行的D-EDF（Double-Earliest Deadline First）策略，既能舍弃部分冗余数据使周期性任务在截止时间前高效完成，又能调度非周期性任务规则的运行提高实时响应速度，使得联邦成员可以高效地处理有优先顺序约束关系的任务，进而改进了运行时支撑环境的实时性.最后证明了D-EDF调度策略的可行性.

Improvement of HLA/RTI real-time performance by scheduling periodic and aperiodic tasks

In order to apply high level architecture (HLA) in some real time systems, real-time performance of run-time infrastructure (RTI) must be guaranteed. Because of precedence constraints of correlated tasks between federates, it is hard to provide predictable response for all tasks, and it is also difficult to ensure the real-time performance of all tasks, especially aperiodic ones. The double-earliest deadline first (D-EDF) strategy of how to schedule overall periodic and aperiodic tasks inside a federate was discussed from the point view of task scheduling theory. The policy can not only discard some redundant data to ensure the periodic tasks completed effectively before their deadlines, but also schedule aperiodic ones running regularly to improve their real-time responding speed. It makes the system effectively handle the tasks with precedence constraints and consequently improves the real-time performance of RTI. The feasibility of the D-EDF scheduling strategy was proved.