Dependable Computing on Inexact Hardware through Anomaly Detection.

Reliability of transistors is on the decline as transistors continue to shrink in size. Aggressive voltage scaling is making the problem even worse. Scaled-down transistors are more susceptible to transient faults as well as permanent in-field hardware failures. In order to continue to reap the benefits of technology scaling, it has become imperative to tackle the challenges risen due to the decreasing reliability of devices for the mainstream commodity market. Along with the worsening reliability, achieving energy efficiency and performance improvement by scaling is increasingly providing diminishing marginal returns. More than any other time in history, the semiconductor industry faces the crossroad of unreliability and the need to improve energy efficiency. These challenges of technology scaling can be tackled by categorizing the target applications in the following two categories: traditional applications that have relatively strict correctness requirement on outputs and emerging class of soft applications, from various domains such as multimedia, machine learning, and computer vision, that are inherently inaccuracy tolerant to a certain degree. Traditional applications can be protected against hardware failures by low-cost detection and protection methods while soft applications can trade off quality of outputs to achieve better performance or energy efficiency. For traditional applications, I propose an efficient, software-only application analysis and transformation solution to detect data and control flow transient faults. The intelligence of the data flow solution lies in the use of dynamic application information such as control flow, memory and value profiling. The control flow protection technique achieves its efficiency by simplifying signature calculations in each basic block and by performing checking at a coarse-grain level. For soft applications, I develop a quality control technique. The quality control technique employs continuous, light-weight checkers to ensure that the approximation is controlled and application output is acceptable. Overall, I show that the use of low-cost checkers to produce dependable results on commodity systems---constructed from inexact hardware components---is efficient and practical.PhDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113341/1/dskhudia_1.pd

On Fault Tolerance Methods for Networks-on-Chip

Technology scaling has proceeded into dimensions in which the reliability of manufactured devices is becoming endangered. The reliability decrease is a consequence of physical limitations, relative increase of variations, and decreasing noise margins, among others. A promising solution for bringing the reliability of circuits back to a desired level is the use of design methods which introduce tolerance against possible faults in an integrated circuit. This thesis studies and presents fault tolerance methods for network-onchip (NoC) which is a design paradigm targeted for very large systems-onchip. In a NoC resources, such as processors and memories, are connected to a communication network; comparable to the Internet. Fault tolerance in such a system can be achieved at many abstraction levels. The thesis studies the origin of faults in modern technologies and explains the classification to transient, intermittent and permanent faults. A survey of fault tolerance methods is presented to demonstrate the diversity of available methods. Networks-on-chip are approached by exploring their main design choices: the selection of a topology, routing protocol, and flow control method. Fault tolerance methods for NoCs are studied at different layers of the OSI reference model. The data link layer provides a reliable communication link over a physical channel. Error control coding is an efficient fault tolerance method especially against transient faults at this abstraction level. Error control coding methods suitable for on-chip communication are studied and their implementations presented. Error control coding loses its effectiveness in the presence of intermittent and permanent faults. Therefore, other solutions against them are presented. The introduction of spare wires and split transmissions are shown to provide good tolerance against intermittent and permanent errors and their combination to error control coding is illustrated. At the network layer positioned above the data link layer, fault tolerance can be achieved with the design of fault tolerant network topologies and routing algorithms. Both of these approaches are presented in the thesis together with realizations in the both categories. The thesis concludes that an optimal fault tolerance solution contains carefully co-designed elements from different abstraction levelsSiirretty Doriast

Robust design of deep-submicron digital circuits

Avec l'augmentation de la probabilité de fautes dans les circuits numériques, les systèmes développés pour les environnements critiques comme les centrales nucléaires, les avions et les applications spatiales doivent être certifies selon des normes industrielles. Cette thèse est un résultat d'une cooperation CIFRE entre l'entreprise Électricité de France (EDF) R&D et Télécom Paristech. EDF est l'un des plus gros producteurs d'énergie au monde et possède de nombreuses centrales nucléaires. Les systèmes de contrôle-commande utilisé dans les centrales sont basés sur des dispositifs électroniques, qui doivent être certifiés selon des normes industrielles comme la CEI 62566, la CEI 60987 et la CEI 61513 à cause de la criticité de l'environnement nucléaire. En particulier, l'utilisation des dispositifs programmables comme les FPGAs peut être considérée comme un défi du fait que la fonctionnalité du dispositif est définie par le concepteur seulement après sa conception physique. Le travail présenté dans ce mémoire porte sur la conception de nouvelles méthodes d'analyse de la fiabilité aussi bien que des méthodes d'amélioration de la fiabilité d'un circuit numérique.The design of circuits to operate at critical environments, such as those used in control-command systems at nuclear power plants, is becoming a great challenge with the technology scaling. These circuits have to pass through a number of tests and analysis procedures in order to be qualified to operate. In case of nuclear power plants, safety is considered as a very high priority constraint, and circuits designed to operate under such critical environment must be in accordance with several technical standards such as the IEC 62566, the IEC 60987, and the IEC 61513. In such standards, reliability is treated as a main consideration, and methods to analyze and improve the circuit reliability are highly required. The present dissertation introduces some methods to analyze and to improve the reliability of circuits in order to facilitate their qualification according to the aforementioned technical standards. Concerning reliability analysis, we first present a fault-injection based tool used to assess the reliability of digital circuits. Next, we introduce a method to evaluate the reliability of circuits taking into account the ability of a given application to tolerate errors. Concerning reliability improvement techniques, first two different strategies to selectively harden a circuit are proposed. Finally, a method to automatically partition a TMR design based on a given reliability requirement is introduced.PARIS-Télécom ParisTech (751132302) / SudocSudocFranceF