异构分布式实时系统中对具有前后依赖关系任务的基于动态可变调度距离容错调度算法

目前的主副版本容错调度算法大多没有考虑任务间的前后依赖关系，但实际中很多任务是具有前后依赖关系的。本文提出了一种基于主副版本动态可变调度距离的任务容错调度算法，该技术通过比较任务间的最晚开始执行时间与最早开始执行时间的差值，安排任务副版本的调度，并且基于此设计了可用于具有前后依赖关系任务调度可重叠技术。本文提出的基于动态可变调度距离的容错调度算法在尽可能让任务最早完成的情况下，提高系统的可靠性，并且优先调度关键路径任务，降低了系统的容错开销。最后通过实验证明本文算法的有效性和优异性。

A Fault Tolerant Scheduling Algorithm Based on Dynamical Distance for Precedence Constrained Task in Hard Real Time Heterogeneous Distributed System

In existed primary/backup fault-tolerant scheduling algorithms almost required that tasks are independent, but in fact tasks in many distributed system are dependent. A novel fault tolerant scheduling algorithm based on dynamical distance between primary and backup tasks was proposed. By this algorithm, according to difference between earliest start time and latest start time between tasks, put the backup task in different position in task queue, and tasks can overlap with each other obey proposed rules. The proposed algorithm（Based on Dynamical Distance fault tolerant scheduling algorithm） improved the last task’s earliest finished time , also improved the task’s guarantee ratio at the same time improve system’s reliability, and the critical path task have priority so that decrease fault tolerant overload .The result of the simulation shows that the algorithm is effective.