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Redundancy is incorporated in safety critical systems for dependability and in traditional redundant systems, computing resources are inefficiently utilized under fault free condition. In this paper, an algorithm Resource Reclaimed Scheme (RR scheme) has been developed for scheduling of periodic tasks with critical aperiodic task arrivals in m-redundancy framework with resource augmentation. A novel task allocation and scheduling ensures effective resource utilization and simultaneous fault tolerant capability with graceful degradation. The proposed algorithm guarantees enhanced performance under fault free condition and less than full functionality up to m-1 faults. An earlier work has dealt with a similar dual system and this paper aims at a generalized m-processor scheme and in both cases, a comparison with the traditional redundant scheme has been studied for the significant impact of this novel idea. As a case study, an Avionic Mission System has being considered and simulation and performance evaluation validating the frame work. An effective use of computing resources and improved process speedup which are critical measures for avionics systems, specially the fuel/weight ratio can have wide ramifications and contribute significantly in enhanced performance capability.

For mission critical applications like Avionics, dependability is to avoid consequences of catastrophic results. Traditionally fault tolerance is implemented using hardware redundancy, the higher the redundancy, greater the cost and possibilities of more failures occurring. In this paper, an adaptive fault tolerant scheduling mechanism developed earlier with augmented performance capability and online fault recovery for a dual redundant system has been extended for an avionics mission system. An algorithm has been developed, simulated and evaluated on the practical case study vis –a- vis a traditional dual redundant system. This paper also roposes an extension of earlier scheme to schedule arrival of either/and critical and non -critical aperiodic tasks. The augmented scheme helps to achieve full functionality when no fault occurs, a fail safe mechanism for a single fault and performance metrics highlights the better computational performance. It elucidates that the use of this adaptive model leverages better in terms of enhanced performance and throughput compared to the existing dual redundant systems.

Dependability is an important requirement in hard real-time applications due to the potentially catastrophic consequences of failures. In these systems, fault tolerance mechanisms like temporal redundancy are adopted to improve reliability. Most of these types of systems are increasingly moving towards integrating critical and non-critical functionalities on the same platform to, e.g., better utilize resources and further reduce cost, and are commonly deployed in environments where errors typically occur in the form of bursts e.g., due to Electro Magnetic Interference (EMI). Consequently, in mixed criticality real-time systems, the designer must guarantee that critical tasks are feasible even under the presence of the error burst, while ensuring the feasibility of the non-critical tasks that are not affected by the burst. We refer to this as Fault Tolerance feasibility (FT-feasibility) of mixed-criticality real-time systems.In this paper, we build on the well established results on Earliest Deadline First (EDF) scheduling, to derive a sufficient test that determines the FT-feasibility of a set of mixed criticality real-time tasks under the assumption that the inter-arrival time between two consecutive error bursts is at least equal to the hyper-period of the taskset.