FTDIS: A Fault Tolerant Dynamic Instruction Scheduling

In this work, we target the robustness for controller scheduler of type Tomasulo for SEU faults model. The proposed fault-tolerant dynamic scheduling unit is named FTDIS, in which critical control data of scheduler is protected from driving to an unwanted stage using Triple Modular Redundancy and majority voting approaches. Moreover, the feedbacks in voters produce recovery capability for detected faults in the FTDIS, enabling both fault mask and recovery for system. As the results of analytical evaluations demonstrate, the implemented FTDIS unit has over 99% fault detection coverage in the condition of existing less than 4 faults in critical bits. Furthermore, based on experiments, the FTDIS has a 200% hardware overhead comparing to the primitive dynamic scheduling control unit and about 50% overhead in comparision to a full CPU core. The proposed unit also has no performance penalty during simulation. In addition, the experiments show that FTDIS consumes 98% more power than the primitive unit.