We introduce a new execution paradigm called assisted execution. In this model, a set of auxiliary "assistant" threads, called nanothreads, is attached to each thread of an application. Nanothreads are very lightweight threads which run on the same processor as the main (application) thread and help execute the main thread as fast as possible. Nanothreads exploit resources that are idled in the processor because of dependencies and memory access delays. Assisted execution has the potential to alter the current trade-offs between static and dynamic execution mechanisms. Nanothreads can monitor and reconfigure the underlying hardware, can emulate hardware and can profile applications with little or no interference to improve the program on-line or off-line. We demonstrate the power of assisted execution with an important application, namely data prefetching to fight the memory wall problem. Simulation results on several SPEC95 benchmarks show that sequential and stride prefet...

Abstract--Parallelism introduces complexities both in hardware and in software. Studying the Tera Computer System and the multiscalar processor gives us a glimpse of these. I.