Fault-tolerant Scheduling Algorithm for Distributed Control Systems Based on Differed Backup-copy
For periodic real-time tasks in distributed control system,a novel fault-tolerant scheduling algorithm is presented.The algorithm fuses active backup-copy technique and passive backup-copy technique and overlapping backup-copy technique in order to take use of their advantages.By differing the time when the backup copy begin running,it reduce overlapping time of primary and backup copies of a task in order to decrease redundancy of backup copy and improve the utilization of processor.The theory for judging schedulability of task set and the method for computing redundant time of backup copy are given.Based on minimizing "worst case response time" and first-fit method,the heuristic task assigning algorithm is given.Finally,simulation experiments are carried out and results prove the feasibility and effectiveness of the algorithm.