Tolerating Permanent Faults With Low-Energy Overhead in Multicore Mixed-Criticality Systems

Due to the battery-operated nature of some embedded Mixed-Criticality Systems, simultaneous energy and reliability management is a crucial issue in designing these systems. We propose two comprehensive schemes, MC-2S and MC-4S, which exploit the standby-sparing technique to tolerate permanent faults through inherent redundancy of multicore systems and maintain the system's reliability against transient faults with low energy overhead. In these schemes, two copies of each high-criticality task are scheduled on different cores to guarantee their timeliness in case of permanent fault occurrence. To guarantee the quality of service of low-criticality tasks, in the MC-2S scheme, one backup copy is considered for each low-criticality task on another core at the design time and partitioned scheduling is employed. The MC-4S scheme exploits semi-partitioned scheduling in which low-criticality tasks migrate to other cores in case of permanent fault or overrun occurrence on one of the cores. We also develop a Demand Bound Function schedulability analysis to guarantee timeliness and propose a preference-oriented scheduling algorithm along with a reliability-aware DVFS method for energy saving. The proposed schemes provide up to 57 percent (39 percent on average) energy saving in comparison to other state-of-the-art methods and enhance the acceptance ratio of the system significantly.