HHC: Hierarchical hardware checkpointing to accelerate fault recovery for SRAM-based FPGAs

As the feature size shrinks to the nanometer scale, SRAM-based FPGAs are increasingly vulnerable to soft errors. Checkpointing is an effective fault recovery technique that can restore the faulty system to its previous fault free state. Since the function of the system needs to be suspended during checkpoint saving and checkpoint restoring, so the Mean Time to Repair (MTTR) of the system is critical to the system performance. In this work, we propose a hierarchical hardware checkpointing (HHC) technique that contains a high-speed on-chip checkpoint and a low-speed off-chip checkpoint to accelerate fault recovery for SRAM-based FPGAs. Most of single event effect (SEE) faults can be recovered by the high-speed on-chip checkpoint, which significantly reduces the MTTR of the system. The memory resource occupation of the on-chip checkpoint is low because HHC only stores the logic states of user bits and check information for configuration bits. Experimental results show that, compared with traditional off-chip checkpoint strategies, the proposed technique can reduce the MTTR of the system by 94.30%. In addition, the memory resource occupation is 11.11% of FPGAs, a little high but can be further optimized.