Research Of Real-time Fault Tolerant Scheduling Strategy

With the real-time system extensively applied in various fields, real-time fault tolerant technique has been deeply studied. Task's execution failure may result in disastrous consequence. That proposes high demands for real-time and reliability for the real-time system.Real-time fault tolerant technique is a solution that put forward for the real-time faults. The main way is redundancy of the system resource. The study for hardware redundancy technology is already very mature. This paper makes some preliminary discussion mainly directed the software redundancy technology for real-time system .There are two software redundancy strategies: N versions software redundancy strategy and recovery block strategy. Mainly studies in recovery block software redundancy strategy. Adopted the primary/alternate versions task redundancy strategy, studies the real-time fault tolerance scheduling algorithm of the two versions in single processor environment .Real-time fault tolerant scheduling algorithms improve on the real-time scheduling algorithms. That improvements are mainly based on the RM algorithm and EDF algorithm. BCE algorithm improves on the RM algorithm. EBPA algorithm proposes the definition of fault tolerant deadline, improves on the EDF algorithm.After defined fault tolerant laxity time and actual available time, a new fault tolerant algorithm. FT-LLF algorithm, which is based on the two definitions and LLF algorithm, is according to the improvement of BCE algorithm on RM algorithm. FT-LLF algorithm eliminates the primary version task abortion rate and decreases the waste on CPU.