17.op/DEC.martin
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.m From rmartin@squeak.CS.Berkeley.EDU Fri Oct  8 14:50:23 1993
A Fast Communication Path for Workstations

Richard P. Martin

(Professor D. E. Culler)

Hewlett-Packard

Current workstation network communication primitives consume 
on the order of 20,000 processor cycles to exchange messages between
user-level processes. The addition of parallel programming environments on top
of the basic protocol processing stacks increases the overhead 
by factors of three to four. As a result of this massive amount of 
overhead, parallel programming tools only deliver the functionality of 
a parallel program, they do not realize any performance.

Previous work at Berkeley on Active Messages delivered the full 
communication performance of MPP hardware to application programs
[1]. We aim to achieve similar results in a workstation
environment. The testbed consists of two HP 9000/720 workstations  
connected by a high-speed fiber optic network. 

The primary purpose of this study will be to achieve 
an extremely fast path from the user-level initiation of a communication
event to the actual hardware transfer, and more importantly, back up
to the user level on the remote workstation. We plan to develop an 
extension of Active Messages that addresses unreliable hardware,
the impact of process scheduling, and flow control in the context
of a workstation operating system. 

[1]	T. von Eicken, D. E. Culler, S. C. Goldstein, and K. E. Schauser,
Active Messages: A Mechanism for Integrated Communication and 
Computation, UC Berkeley Computer Science Division, Report No. UCB/CSD 92/675, March 1992.