基于优先级混合策略的回卷恢复容错实时系统的可调度性

Schedulability of rollback recovery fault-tolerant real-time system based on priority mixed strategy

实时系统具有严格的实时性及高度的可靠性要求。考虑到系统可能出错的情况,对回卷恢复容错模型下实时系统的可调度性进行了研究,提出了容错优先级混合策略,并推导出该策略下任务最坏响应时间的计算公式。结合系统的可调度性分析,提出了混合策略的优先级配置搜索算法(FTPCS_MS算法),该算法将最优容错优先级混合配置的搜索空间由O(nn)降低为O(n2)。仿真实验表明,容错优先级混合策略能够在继承策略的基础上进一步提升系统的容错能力。

A real-time system must guarantee the stringent requirements of real-time response and reliability.Taking account of the effects of errors,an investigation of the schedulability of fault-tolerant real-time systems was conducted based on the rollback recovery fault-tolerant model.A priority mixed strategy of fault-tolerance was proposed,and the computing formula of worst-case response time of a task under the new strategy is deduced.The new strategy allows the faulty task to execute at higher or lower priority levels.According to the schedulability analysis,an efficient priority assignment search algorithm（FTPCS_MS） was proposed.The algorithm reduces the search space of optimal fault-tolerant priority mixed assignment from O（n^n） to O（n^2）.The simulation shows that the mixed strategy can improve system fault resilience efficiently.