Channel allocation protocol for reconfigurable Optical Network-on-Chip

International audienceThe current evolution of system architectures leads towards implementation of large number of processor cores into the same circuit. This evolution actually supports the performance increase and provides the capability to support the execution of very complex applications. Nevertheless, if these new architec- tures propose high computational performances, an important bottleneck appears for the communications between processors. Implementation of a classical electrical NoC is generally too limited for such architectures and cannot support the bandwidth required by the applications. To address this problem, Optical Network-on-Chips (ONoCs) are studied since several years. By using integrated optical technology in addition to classical technology, an ONoC can significantly increase bandwidth and decrease latency in a MPSoC based on a 3D architecture. The integration of such optical layer into a MPSoC requires to define a protocol for the communication, and in particular a protocol for the reservation of the wavelengths which ensures the communications. This paper addresses this problem and proposes a wavelength reservation protocol handled by an Optical Network Interface (ONI) Manager for reconfigurable ONoC based on shared waveguide. It allows to efficiently allocate, at runtime, the optical communication channels for a manycore architecture. The paper describes the ONI manager architecture and reservation protocol. To evaluate the performances of this interface, we have implemented it with 28nm FDSOI technology. The synthesis results demonstrate that our interface can support a high frequency 550 MHz with 6 wavelengths managed. From these results, we can be optimistic about the scaling of the ONoC and its capacity to manage a large number of processors and more wavelengths