CAREER: Horseshoes and Hand Grenades: Exploiting Error Tolerance in Applications

传统上，大多数可靠性项目的目标都是防止各种错误。研究人员现在发现，并非所有的错误都会导致失败。由于并非所有输入都会影响最终结果，因此可以在电路内屏蔽一些错误。通过防止所有错误，而不仅仅是那些改变结果的错误，浪费了时间和精力。该项目建议探索允许在不改变最终结果的情况下发生错误的技术。在面部识别或语音识别等许多应用中，软件不会注意到许多数据错误，具体取决于特定的数据。例如，如果我们在用于语音识别的传入音频信号中翻转一个比特，可能根本不会影响结果。尽管在一个样本中有错误，正确的单词仍可被识别。然而，一个关键的观察是，即使是这些应用程序也不能很好地抵抗控制流错误。例如，如果语音识别软件在完成对音频信号的分析之前停止，则很可能会识别错误的单词，从而导致失败。这个项目探索了如何利用对不可靠性的部分容忍。可以设计更有效的可靠性机制，其仅针对重要指令，而不是所有指令。在容错能力更强的应用程序中，可以在系统中引入错误以加快系统速度--允许进程继续进行，而无需等待缓慢的操作。为了发现和利用容错性，该项目将确定10-15个容错的应用程序，开发启发式方法来确定哪些指令比其他指令更容错，开发特定的技术来有效地仅保护关键指令不受错误的影响，并开发机制将错误引入不太重要的高延迟指令中，以节省电力和/或提高性能。

The goal in most reliability projects has, traditionally, been to prevent errors of all kinds. Researchers are now discovering that not all errors cause a failure. Some errors can be masked within the circuits as not all inputs affect final results. By preventing all errors rather than only those errors that change a result, time and power get wasted. This project proposes to explore techniques which allow errors to occur that do not change final results. In many applications such as facial recognition or voice recognition, many of the data errors will not be noticed by the software, depending on the particular data. For example, if we one bit gets flipped in an incoming audio signal for voice recognition, it may not affect the result at all. The proper word may be recognized despite the error in one sample. A key observation, however, is that even these applications are not very resistant to control flow errors. For example, if the voice recognition software stops before it completes its analysis of the audio signal, the wrong word would most likely be recognized leading to failure. This project explores how to take advantage of partial tolerance to unreliability. More efficient reliability mechanisms can be designed that are targeted towards only the important instructions, not all instructions. In even more tolerant applications, errors can be introduced into the system in order to speed up the system--allowing the process to proceed without waiting for slow operations. In order to discover and exploit error-tolerance, this project will identify 10-15 applications that are tolerant to errors, develop heuristics to determine which instructions are more tolerant to error than others, develop specific techniques for efficiently protecting only critical instructions from errors, and develop mechanisms to introduce errors into less important, high-latency instructions in order to save power and/or improve performance.