A realistic assessment of optical networks-on-chip (ONoCs) can be performed only in the context of a comprehensive floorplanning strategy for the system as a whole, especially when the 3-D stacking of electronic and optical layers is implemented. This paper fosters layout-aware ONoC design by developing a physical mapping methodology for wavelength-routed ONoC topologies subject to the floorplanning, placement, and routing constraints that arise in a 3-D-stacked environment. As a result, this paper is able to compare the power efficiency and signal-to-noise ratio of ring-based versus filter-based wavelength-routed topologies as determined by their physical design flexibility.

Not availableMarta Ortín-Obón, Darío Suárez-Gracia, María Villarroya-Gaudó, Cruz Izu, Víctor Viñals-Yúfer

Power saving is a prevailing concern in desktop computers and, especially, in battery‐powered devices such as mobile phones. This is generating a growing demand for power‐aware graphics applications that can extend battery life, while preserving good quality. In this paper, we address this issue by presenting a real‐time power‐efficient rendering framework, able to dynamically select the rendering configuration with the best quality within a given power budget. Different from the current state of the art, our method does not require precomputation of the whole camera‐view space, nor Pareto curves to explore the vast power‐error space; as such, it can also handle dynamic scenes. Our algorithm is based on two key components: our novel power prediction model, and our runtime quality error estimation mechanism. These components allow us to search for the optimal rendering configuration at runtime, being transparent to the user. We demonstrate the performance of our framework on two different platforms: a desktop computer, and a mobile device. In both cases, we produce results close to the maximum quality, while achieving significant power savings.

Out of all the optical network-on-chip topologies, the ring has been proved to be far superior to its competitors: the contention-free all-to-all communications offer the lowest latency possible, while its clean physical design with few crossings and ring resonators provides unmatchable power results. The ring implements simultaneous communications by using a communication matrix that sets a distinctive waveguide-wavelength pair for each of them. That communication matrix has a high impact on energy consumption, but so far there have been very few efforts towards optimizing and automating its design. As far as we know, we propose the best optical ring design algorithm, which produces rings with the lowest number of wavelengths and waveguides in the literature. The algorithm is completed with a layout-aware and fully automated laser power calculation framework to help the user choose the most power-efficient design point.

Although many valuable research works have investigated the properties of optical networks-on-chip (ONoCs), the vast majority of them lack an accurate exploration of the network interface architecture (NI) required to support optical communications on the silicon chip. The complexity of this architecture is especially critical for a specific kind of ONoCs: wavelength-routed ones. From a logical viewpoint, they can be considered as full nonblocking crossbars, thus the control complexity is implemented at the NIs. To our knowledge, this paper proposes the first complete NI architecture for wavelength-routed optical NoCs, by coping with the intricacy of networking issues such as flow control, buffering strategy, deadlock avoidance, serialization, and above all, with their codesign in a complete architecture