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Author Goodman, James R. ♦ Scott, Steven L. ♦ Vernon, Mary K.
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Abstract The Scalable Coherent Interface (SCI) is an emerging IEEE standard that provides computer-bus-like services to a set of nodes via fast, unidirectional links. This paper presents the first detailed performance study of the SCI ring, using both analytical models and simulation. Performance is analyzed for uniform and nonuniform traffic, and the effect of the ring's flow control protocol is studied.The queueing model is based on an M/G/1 queue, augmented to include the effect of packet trains on the mean and variance of the source transmission time. The model is validated against simulation results, and shown to be quantitatively accurate for uniform workloads, and at least qualitatively accurate for nonuniform workloads. The flow control mechanism is shown to effectively prevent node starvation and reduce the ability of nodes to unfairly consume ring bandwidth, but at the cost of decreased overall ring utilization. The SCI ring is also compared to a standard bus, modeled with a simple M/G/1 queue, and shown to provide substantially higher throughputs and lower latency than a bus with realistic clock speeds.
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 1981-04-01
Publisher Place New York
Journal ACM SIGARCH Computer Architecture News (CARN)
Volume Number 20
Issue Number 2
Page Count 12
Starting Page 403
Ending Page 414


Source: ACM Digital Library