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Cost‐effective queue schemes for reducing head‐of‐line blocking in fat‐trees
Author(s) -
EscuderoSahuquillo J.,
Garcia P. J.,
Quiles F. J.,
Flich J.,
Duato J.
Publication year - 2011
Publication title -
concurrency and computation: practice and experience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.309
H-Index - 67
eISSN - 1532-0634
pISSN - 1532-0626
DOI - 10.1002/cpe.1764
Subject(s) - hol , computer science , blocking (statistics) , routing (electronic design automation) , computer network , static routing , distributed computing , network topology , routing algorithm , tree (set theory) , queue , network packet , simple (philosophy) , routing protocol , mathematics , mathematical analysis , philosophy , epistemology , programming language
SUMMARY The fat‐tree is one of the most common topologies among the interconnection networks of the systems currently used for high‐performance parallel computing. Among other advantages, fat‐trees allow the use of simple but very efficient routing schemes. One of them is a deterministic routing algorithm that has been recently proposed, offering a similar (or better) performance than adaptive routing while reducing complexity and guaranteeing in‐order packet delivery. However, as other deterministic routing proposals, this deterministic routing algorithm cannot react when high traffic loads or hot‐spot traffic scenarios produce severe contention for the use of network resources, leading to the appearance of Head‐of‐Line (HoL) blocking, which spoils the network performance. In that sense, we describe in this paper two simple, cost‐effective strategies for dealing with the HoL‐blocking problem that may appear in fat‐trees with the aforementioned deterministic routing algorithm. From the results presented in the paper, we conclude that, in the mentioned environment, these proposals considerably reduce HoL‐blocking without significantly increasing switch complexity and the required silicon area. Copyright © 2011 John Wiley & Sons, Ltd.