CAREER: Cooperative Redundant Threads

这项提议的研究使计算机能够达到更高的速度，而在这个时候，即使是一点点的性能提升也越来越难以通过传统手段实现。第一个关键发现是，计算机程序指定的许多指令并不是产生正确答案所严格要求的。也就是说，可以构造一个更短的程序，在更短的时间内产生相同的输出。提出了一种新颖的方法，通过完全绕过程序中预计不必要的部分来创建一个更短的程序。然而，通过跳过程序的某些部分，处理器无法验证这样做是否正确（因为程序已被转换）。第二个关键发现是，完整程序可以与短程序并发运行，以验证短程序的正确性，而不会显著降低短程序的运行速度。提出的方法被称为滑流范式，这是一种赛车技术，两辆车在空气动力学上合作来加速两辆车（滑流）。类似地，滑流处理器完成程序的两个冗余副本比传统处理器完成单个副本要快。在没有额外支持的情况下，还透明地利用冗余执行来实现容错。最后，Slipstream范式可以在新兴的多线程处理器上实现，而无需从根本上重组它们的架构。

The proposed research enables computers to attain higher speeds, at a time when even slight performance gains are increasingly difficult to achieve by conventional means. The first key discovery is that many instructions specified by a computer program are not strictly required for producing the correct answer. That is, a much shorter program can be constructed that produces the same output in a much shorter period of time. A novel method is proposed for creating a shorter program on-the-fly by completely bypassing parts of the program predicted to be unnecessary. By skipping parts of the program, however, the processor cannot verify that it was alright to do so (because the program has been transformed). The second key discovery is that the full program can be run concurrently with the short program, in order to verify the short program is correct, without noticeably slowing down the short program. The proposed method is called the Slipstream Paradigm, after a technique in auto racing where two cars collaborate aerodynamically to speed up both cars (slipstreaming). Similarly, a slipstream processor finishes two redundant copies of the program sooner that a conventional processor finishes a single copy. Redundant execution is also transparently leveraged for fault tolerance with no additional support. Finally, the Slipstream Paradigm is implementable on emerging multithreaded processors without fundamentally reorganizing their architecture.