Prediction-Table Based Fault-Tolerant Real-Time Scheduling Algorithm

In order to predict accurately whether primary versions of real-time tasks is executable in software fault-tolerant module, a new algorithm, PTBA, prediction-table based algorithm, is presented. PTBA uses prediction-table to predict whether a host primary can meet its pre-deadline. Prediction-table contains the pre-assignment information of tasks between the current time and the alternates´ notification time. If the prediction result shows that host primary has not enough time to execute, it will be aborted. Otherwise, prediction-table is referenced to schedule tasks with low overhead. The novelty of PTBA is that it schedules primaries according to their corresponding alternates´ notification time and has no extra scheduling overhead in prediction-table mode. Simulation results show that PTBA allows more execution time for primaries and wastes less processor time than the well-known similar algorithms. PTBA is appropriate to the situation where the periods of tasks are short and software fault probability is low