Performance Evaluation of Primary Backup Fault Tolerant Scheduling for Single Processor Systems

One of the core functions of an operating system is scheduling applications such that overall system provides a satisfactory result. Real-time embedded systems have an additional requisite to provide correct output within deadline; failure could be catastrophic for safety critical systems. In this paper, the feasibility of Primary-Backup Fault Tolerant Scheduling (PB-FTS) to handle application level faults by means of switching between primary and secondary copy of task is examined. PB-FTS, which is the secondary scheduler, is evaluated over the different traditional scheduling algorithms such as Rate Monotonic (RM), Deadline Monotonic (DM) and Earliest Deadline First (EDF) under various fault scenarios. The fault handling capacity and performance of PB-FTS is measured by running MATLAB based simulations. Simulation results indicate a decreasing trend in fault handling capacity from 100% at 0.6 utilization factor for one fault to 53% at 1.0 utilization factor for three faults.