Enhancing Entropy Throttling: New Classes of Injection Control in Interconnection Networks

Takashi YOKOTA  Kanemitsu OOTSU  Takeshi OHKAWA  

IEICE TRANSACTIONS on Information and Systems   Vol.E99-D   No.12   pp.2911-2922
Publication Date: 2016/12/01
Publicized: 2016/08/25
Online ISSN: 1745-1361
DOI: 10.1587/transinf.2016PAP0007
Type of Manuscript: Special Section PAPER (Special Section on Parallel and Distributed Computing and Networking)
Category: Interconnection network
parallel computers,  interconnection networks,  congestion control,  throttling,  

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State-of-the-art parallel computers, which are growing in parallelism, require a lot of things in their interconnection networks. Although wide spectrum of efforts in research and development for effective and practical interconnection networks are reported, the problem is still open. One of the largest issues is congestion control that intends to maximize the network performance in terms of throughput and latency. Throttling, or injection limitation, is one of the center ideas of congestion control. We have proposed a new class of throttling method, Entropy Throttling, whose foundation is entropy concept of packets. The throttling method is successful in part, however, its potentials are not sufficiently discussed. This paper aims at exploiting capabilities of the Entropy Throttling method via comprehensive evaluation. Major contributions of this paper are to introduce two ideas of hysteresis function and guard time and also to clarify wide performance characteristics in steady and unsteady communication situations. By introducing the new ideas, we extend the Entropy throttling method. The extended methods improve communication performance at most 3.17 times in the best case and 1.47 times in average compared with non-throttling cases in collective communication, while the method can sustain steady communication performance.