Message-Based Efficient Remote Memory Access on a Highly Parallel Computer EM-X

Yuetsu KODAMA  Hirohumi SAKANE  Mitsuhisa SATO  Hayato YAMANA  Shuichi SAKAI  Yoshinori YAMAGUCHI  

IEICE TRANSACTIONS on Information and Systems   Vol.E79-D   No.8   pp.1065-1071
Publication Date: 1996/08/25
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Issue on Architectures, Algorithms and Networks for Massively Parallel Computing)
Category: Architectures
Fine grain communication,  multithread architecture,  distributed shared memory,  

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Communication latency is central to multiprocessor design. This study presents the design principles of the EM-X distributed-memory multiprocessor towards tolerating communication latency. The EM-X overlaps computation with communication for latency tolerance by multithreading. In particular, we present two types of hardware support for remote memory access: (1) priority-based packet scheduling for thread invocation, and (2) direct remote memory access. The priority-based scheduling policy extends a FIFO ordered thread invocation policy to adopt to different computational needs. The direct remote memory access is designed to overlap remote memory operations with thread execution. The 80-processor prototype of EM-X is developed and is operational since December 1995. We execute several programs on the machine and evaluate how the EM-X effectively overlaps computation with communication toward tolerating communication latency for high performance parallel computing.