A STUDY OF THE EARTH-MANNA MULTITHREADED SYSTEM

Multithreaded architectures have been proposed for future multiprocess or systems. However; some open issues remain. Can multithreading be su pported in a multiprocessor so that it can tolerate synchronization an d communication latencies, with little intrusion on the performance of sequentially-executed code? How much does such support contribute to scalable performance when communication and synchronization demands ar e high? In this paper, we describe the design of EARTH, an architectur e which addresses these issues. Each processor in EARTH has an off-the -shelf Execution Unit (EU) for executing threads, and an ASIC Synchron ization Unit (SU) supporting dataflow-like thread synchronizations, sc heduling, and remote requests. In preparation for an implementation of the SU, we have emulated a basic EARTH model on MANNA 2.0, an existin g multiprocessor whose hardware configuration closely matches EARTH. T his EARTH-MANNA testbed is fully functional, enabling us to experiment with large benchmarks with impressive speed. With this platform, we d emonstrate that multithreading support can be efficiently implemented (with little emulation overhead) in a multiprocessor without a major i mpact on uniprocessor performance. Also, we measure how much basic mul tithreading support can help in tolerating increasing communication/sy nchronization demands.