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Energy Implications of Photonic Networks With Speculative Transmission

Watts, PM; Moore, SW; Moore, AW; (2012) Energy Implications of Photonic Networks With Speculative Transmission. Journal Of Optical Communications And Networking , 4 (6) 503 - 513. 10.1364/JOCN.4.000503. Green open access


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Speculative transmission has been proposed to overcome the high latency of setting up end-to-end paths through photonic networks for computer systems. However, speculative transmission has implications for the energy efficiency of the network, in particular, control circuits are more complex and power hungry and failed speculative transmissions must be repeated. Moreover, in future chip multiprocessors (CMPs) with integrated photonic network end points, a large proportion of the additional energy will be dissipated on the CMP. This paper compares the energy characteristics of scheduled and speculative chip-to-chip networks for shared memory computer systems on the scale of a rack. For this comparison, we use a novel speculative control plane which reduces energy consumption by eliminating duplicate packets from the allocation process. In addition, we consider photonic power gating to reduce processor chip energy dissipation and the energy impact of the choice between semiconductor optical amplifier and ring resonator switching technologies. We model photonic network elements using values from the published literature as well as determine the power consumption of the allocator and network adapter circuits, implemented in a commercial low leakage 45 nm CMOS process. The power dissipated on the CMP using speculative networks is shown to be roughly double that of scheduled networks at saturation load and an order of magnitude higher at low loads.

Type: Article
Title: Energy Implications of Photonic Networks With Speculative Transmission
Open access status: An open access version is available from UCL Discovery
DOI: 10.1364/JOCN.4.000503
Publisher version: http://dx.doi.org/10.1364/JOCN.4.000503
Language: English
Additional information: © 2012 OSA/IEEE. Personal use of this material (accepted version) is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Keywords: Assignment and routing algorithms, Networks, Optical interconnects
UCL classification: UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Engineering Science
URI: http://discovery.ucl.ac.uk/id/eprint/1352472
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