Nanoscale Coded Computation and Storage

半导体工业面临的一个关键挑战是应对芯片尺寸减小所导致的高错误率。瞬态故障、永久缺陷和随机装配使传统结构难以实现。围绕缺陷的路由和应对大量的器件变化已经进行了研究。然而，对于如何有效地处理计算过程中的高速率瞬态错误，人们知之甚少。本研究将为暂态故障容限提供一种新的系统方法。目标是帮助半导体工业更好地理解纳米级可靠性问题的维度。这项研究与空间应用有关，其中误差控制可以作为辐射硬化的替代方案。本研究采用了一种复杂的容错计算方法。首先，它利用差分可靠性，也就是说，它检查使用少量可靠元素来监督大量不可靠元素。其次，它借鉴了编码理论的成功，探索了对潜在错误计算的输入和输出进行编码的特殊和一般方法，特别注意了Spielman在1996年采用的一种开创性方法。通过编码计算，可以检测和纠正编码输出的错误。第三，它检查了小型检查计算的使用，然后是可能的回滚，其中大多数检查是使用不可靠的元素完成的。允许计算在时间上而不是在空间上重复，可以减少无故障计算的开销。设计工作期望对实践产生直接影响，而一般理论的发展期望具有长期影响。

A key challenge before the semiconductor industry is coping with high errors rates resulting from the decreasing size of chip features. Transient faults, along with permanent defects and stochastic assembly, make it difficult to implement traditional architectures. Research has been done on routing arounddefects and coping with large amounts of device variation. Little is known, however, about how to cope efficiently with high-rates of transient errors during computation. This research will take a new systematic approach to the tolerance of transient failures. The goal is to help the semiconductor industry to better understand the dimensions of the nanoscale reliability problem. This research has relevance to space-borne applications where error control can serve as an alternative to radiation hardening. This research employs a sophisticated approach to fault-tolerant computation. First, it exploits differential reliability, that is, it examines the use of a small number of reliable elements to oversee a large number ofunreliable elements. Second it draws on the success of coding theory to explore both special and general methods to encode inputs and outputs of a potentially faulty computation, paying particular attention to a seminal approach taken by Spielman in 1996. By encoding computations, faults at the encoded outputs can then be detected and corrected. Third, it examines the use of small check computations followed by possible rollback, where most of the checking is done using unreliable elements. Allowing a computation to berepeated in time, rather than space, reduces the overhead of fault free computations. The design work is expected to have immediate impact on practice whereas development of a general theory is expected to have alonger-term impact.