Abstract
Networks-on-Chip (NoCs) are considered a viable solution to fully exploit the computational power of multi- and many-cores, but their non negligible power consumption requires ad hoc power-performance design methodologies. In this perspective, several proposals exploited the possibility to dynamically tune voltage and frequency for the interconnect, taking steps from traditional CPU-based power management solutions. However, the impact of the actuators, i.e. the limited range of frequencies for a PLL (Phase Locked Loop) or the time to increase voltage and frequency for a Dynamic Voltage and Frequency Scaling (DVFS) modules, are often not carefully accounted for, thus overestimating the benefits. This paper presents a control-based methodology for the NoC power-performance optimization exploiting the Dynamic Frequency Scaling (DFS). Both timing and power overheads of the actuators are considered, thanks to an ad hoc simulation framework. Moreover the proposed methodology eventually allows for user and/or OS interactions to change between different high level power-performance modes, i.e. to trigger performance oriented or power saving system behaviors. Experimental validation considered a 16-core architecture comparing our proposal with different settings of threshold-based policies. We achieved a speedup up to 3 for the timing and a reduction up to 33.17% of the power ∗ time product against the best threshold-based policy. Moreover, our best control-based scheme provides an averaged power-performance product improvement of 16.50% and 34.79% against the best and the second considered threshold-based policy setting.
Davide Zoni
Associate Professor
Davide Zoni received the Master Degree in Computer Engineering in 2010 and the Ph.D. in Information Technology in 2014, both from Politecnico di Milano, Italy, where he holds a Post-Doc position at DEIB—Dipartimento di Elettronica Informazione e Bioingegneria. His research interests include RTL design and low-power optimizations for multi-cores with particular emphasis on cache coherence protocols, on-chip interconnect and hardware-based side-channel countermeasures.
Federico Terraneo
Associate Professor
Federico Terraneo received his B.Sc. and M.Sc. degrees in computer engineering from the Politecnico di Milano, Milan, Italy, and his Ph.D. degree in Information Technology from Politecnico di Milano in 2015. Currently he holds a Postdoc position at Politecnico di Milano. His research interests include embedded systems and the application of principles of control theory to the design of software systems. Since 2008 he has been the main developer and maintainer of the Miosix embedded operating system.
William Fornaciari
Associate Professor
William Fornaciari has published six books and over 200 papers, earning five best paper awards, an IEEE certification, and three international patents on low power design. Since 1997, he has participated in 18 EU-funded projects. His research focuses on multi/many-core architectures, NoC, low power design, and more.