基于对象的分布式实时系统调度模型研究

为了解决分布式实时系统有关分配和调度等问题,给出并用形式化方法描述了一种基于对象分布式实时系统调度的通用模型。该模型包括表示时限的绝对时间约束,表示周期属性的周期约束,表示各种前趋关系和同步要求的相对时间约束以及保证资源使用一致性的一致性约束,此外该模型克服了以往模型不能在应用系统的逻辑和功能部件上描述系统实时的约束的不足,允许从方法和活动上描述所需的约束,降低了单一约束描述的繁杂程度,为了能够使用现有调度算法进行任务调度,讨论了约束转换的问题,给出了高层约束到底层约束的转换规则和相应的转换算法。

RESEARCH ON A MODEL FOR SCHEDULING OBJECT-BASED DISTRIBUTED REAL-TIME SYSTEMS

A general formal model for scheduling object-based distributed real-time systems is presented. The model includes absolute timing constraints to represent deadlines, periodic constraints to formulate periodicity, relative constraints to model several kinds of timed precedence relations and synchronization requirements, and consistency constraints to enforce consistent use of resources. With the proposed model, specifying the timing constraints of real-time systems on the logical and functional components of an application is possible, thus reducing the complexity of constraints specification. The rules and algorithm of converting scheduling constraints of different types are also discussed to make the existing scheduling algorithms available for the model.