Security-driven fault tolerant scheduling algorithm for high dependable distributed real-time system

Critical real time system must run under high dependable environment which guarantees a high level of reliability and security. Fault tolerance and security technique has played an important role in building such environment. In this paper, we provide an improved technique to schedule such tasks with high reliability and security requirement on high dependable distributed real time system. First, the paper analyzed the scheduling problem on high dependable distributed real time system and provided a refined scheduling model which accurately described processors, fault tolerant tasks and security overhead. Based on the scheduling model, it proposed a new and better scheduling algorithm - Security Driven Fault Tolerant Scheduling Algorithm (SDFT) which extended FTRMFF algorithm to tolerate N processors failure at one time, and it introduced a new global scheduler to improve efficiency of scheduling process. Moreover, the SDFT supported flexible security policy applied on real time tasks according to its security requirement and considered the effect of security overhead during scheduling. In addition, the paper adopted and extended the Completion Time Test (CTT) as the schedulability criteria. Simulation experiments showed the SDFT algorithm could achieve better reliability and security at the cost of less number of processors.