A Survey of Fault-Tolerance Techniques for Embedded Systems from the Perspective of Power, Energy, and Thermal Issues

The relentless technology scaling has provided a significant increase in processor performance, but on the other hand, it has led to adverse impacts on system reliability. In particular, technology scaling increases the processor susceptibility to radiation-induced transient faults. Moreover, technology scaling with the discontinuation of Dennard scaling increases the power densities, thereby temperatures, on the chip. High temperature, in turn, accelerates transistor aging mechanisms, which may ultimately lead to permanent faults on the chip. To assure a reliable system operation, despite these potential reliability concerns, fault-tolerance techniques have emerged. Specifically, fault-tolerance techniques employ some kind of redundancies to satisfy specific reliability requirements. However, the integration of fault-tolerance techniques into real-time embedded systems complicates preserving timing constraints. As a remedy, many task mapping/scheduling policies have been proposed to consider the integration of fault-tolerance techniques and enforce both timing and reliability guarantees for real-time embedded systems. More advanced techniques aim additionally at minimizing power and energy while at the same time satisfying timing and reliability constraints. Recently, some scheduling techniques have started to tackle a new challenge, which is the temperature increase induced by employing fault-tolerance techniques. These emerging techniques aim at satisfying temperature constraints besides timing and reliability constraints. This paper provides an in-depth survey of the emerging research efforts that exploit fault-tolerance techniques while considering timing, power/energy, and temperature from the real-time embedded systems’ design perspective. In particular, the task mapping/scheduling policies for fault-tolerance real-time embedded systems are reviewed and classified according to their considered goals and constraints. Moreover, the employed fault-tolerance techniques, application models, and hardware models are considered as additional dimensions of the presented classification. Lastly, this survey gives deep insights into the main achievements and shortcomings of the existing approaches and highlights the most promising ones

Fault tolerance core: a framework for application-aware reliability

As processor manufacturers keep pushing the limits of the transistor, the reliability of computer systems has become an increasing concern. Various fault tolerance techniques have been developed in an effort to provide reliable computing in the presence of faults. These approaches suffer from either a high resource cost or high performance overhead. This thesis presents a design for a Fault Tolerance Core (FTC) that uses configurable application-aware hardware modules for improving reliability. Application-aware fault tolerance is achieved by detecting perturbations in application execution through the monitoring of processor pipeline signals. This approach leverages hardware resources more efficiently than replication. The FTC achieves low overhead by placing fault tolerance hardware separately from the processing core, minimizing the processor data collection hardware, and by performing fault detection in the background. This thesis presents work that has been completed towards the achievement of a FTC. This work includes a hardware assisted incremental checkpoint, an application hang detector and a preliminary FTC framework for integrating these into a Leon3 microprocessor. All modules have been implemented and tested on a Leon3 synthesized atop a Stratix III FPGA running a Linux environment. A hardware fault injector capable of modifying 9 distinct processor pipeline signals has been implemented for performing validation experiments on the modules