NDLI: VLSI micro-architectures for high-radix crossbar schedulers

Content Provider	IEEE Xplore Digital Library
Author	Passas, G. Katevenis, M. Pnevmatikatos, D.
Copyright Year	2011
Description	Author affiliation: Institute of Computer Science (ICS), Foundation for Research and Technology - Hellas (FORTH), Heraklion, Crete, Greece (Passas, G.; Katevenis, M.; Pnevmatikatos, D.)
Abstract	We study the scaling of parallel-matching crossbar schedulers to radices above 100. First, we examine a traditional microarchitecture that implements the matching decision of each input and each output of the crossbar in a separate arbiter block and communicates the matching decisions between the input and the output arbiters through global point-to-point links. Using simple models and experimentation with 90nm CMOS layouts, we show that this architecture is expensive because the global point-to-point links take up $O(N^{4})$ area, where N the radix of the crossbar. Next, by observing that the wiring of an arbiter fits in a minimal O(NlogN) area, we propose a novel microarchitecture that inverts the locality of wires by orthogonally interleaving the input with the output arbiters, thus lowering the wiring area of the scheduler down to $O(N^{2}log^{2}N).$ Using this architecture, the scheduler for a radix-128 FIFO, VOQ, or 2-VC crossbar becomes gate limited, fitting in 3.6, 7.2, and $7.2mm^{2}$ respectively, which is a 40, 50, and 70% improvement compared to the traditional. Moreover, the proposed schedulers find a new match in less than 10ns, thus allowing a minimum packet below 30Bytes at 24Gb/s line rate. Based on these findings, we conclude that crossbar schedulers are feasible even for radices above 100.
Starting Page	217
Ending Page	224
File Size	1993162
Page Count	8
File Format	PDF
ISBN	9781450307208
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2011-05-01
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Association for Computing Machinery, Inc. (ACM)
Subject Keyword	Algorithm design and analysis Layout Crossbar Parallel Iterative Matching ASICs
Content Type	Text
Resource Type	Article

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