SCHEDULE: NOV 10-16, 2007

Age-Based Packet Arbitration in Large-Radix k-ary n-cubes

Session: Network Switching and Routing

Event Type: Paper, Best Paper (BP) Finalist

Time: 10:30am - 11:00am

Session Chair: Keith Underwood

Author(s): Dennis Abts, Deborah Weisser

Location: A2 / A5

Abstract:
As applications scale to increasingly large processor counts, the interconnection network is frequently the limiting factor in application performance. In order to achieve application scalability, the interconnect must maintain high bandwidth while minimizing variation in packet latency. As the offered load in the network increases with growing problem sizes and processor counts, so does the expected maximum packet latency in the network, directly impacting performance of applications with any synchronized communication. Age-based packet arbitration reduces the variance in packet latency as well as average latency. This paper describes the Cray XT router packet aging algorithm which allows globally fair arbitration by incorporating "age" in the packet output arbitration. We describe the parameters of the aging algorithm and how to arrive at appropriate settings. We show that an efficient aging algorithm reduces both the average packet latency and the variance in packet latency on communication-intensive benchmarks.

Awards:Best Paper Nomination

This paper can be found in the ACM Digital Libaries
Click here for ACM

Chair/Author Details:

Keith Underwood (Chair)
Sandia National Labs

Dennis Abts
Cray, Inc

Deborah Weisser
Google, Inc.

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