Multi-Voltage Variable Pipeline Routers with the Same Clock Frequency for Low-Power Network-on-Chips Systems

Akram BEN AHMED  Hiroki MATSUTANI  Michihiro KOIBUCHI  Kimiyoshi USAMI  Hideharu AMANO  

IEICE TRANSACTIONS on Electronics   Vol.E99-C   No.8   pp.909-917
Publication Date: 2016/08/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.909
Type of Manuscript: Special Section PAPER (Special Section on Low-Power and High-Speed Chips)
Network-on-Chips,  multi-Vdd,  low power networks,  

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In this paper, the Multi-voltage (multi-Vdd) variable pipeline router is proposed to reduce the power consumption of Network-on-Chips (NoCs) designed for Chip Multi-processors (CMPs). The multi-Vdd variable pipeline router adjusts its pipeline depth (i.e., communication latency) and supply voltage level in response to the applied workload. Unlike Dynamic Voltage and Frequency Scaling (DVFS) routers, the operating frequency remains the same for all routers throughout the CMP; thus, omitting the need to synchronize neighboring routers working at different frequencies. Two types of router architectures are presented: a Coarse-Grained Variable Pipeline (CG-VP) router that changes the voltage supplied to the entire router, and a Fine-Grained Variable Pipeline (FG-VP) router that uses a finer power partition. The evaluation results showed that the CG-VP and FG-VP routers achieve a 22.9% and 35.3% power reduction on average with 14% and 23% area overhead in comparison with a baseline router without variable pipelines, respectively. Thanks to the adopted look-ahead mechanism to switch the supply voltage, the performance overhead is only 4.4%.