AWGR-Based Optical Topologies for Scalable and Efficient Global Communications in Large-Scale Multi-Processor Systems

Abstract

In large-scale multi-processor computing systems, global communications are typically supported by an auxiliary network (e.g., IBM Blue Gene) or with hardware support in the network (e.g., NEC Earth Simulator). We explore the potential for realizing efficient global communications that can scale beyond a million processors by harnessing the unique parallelism and wavelength routing properties of optical devices. Specifically, we use an arrayed waveguide grating router (AWGR) device as the basic building block in realizing scalable global communication. The AWGR is a passive switch fabric (wavelength router) that uses multiple wavelengths to interconnect outputs and inputs by following a specific cyclic wavelength routing (permutation) pattern. We analyze different network topologies using AWGR devices for barrier synchronization and propose techniques to pick parameters of the network for a given number of processors. We compare the performance and energy consumption for barrier synchronization with what is achievable with state-of-the-art electrical networks.

Segment Switching: A New Switching Strategy for Optical HPC Networks

“…Figure 2 shows the block diagram of the devised optical switch. The central module is an Arrayed Waveguide Grating Router (AWGR) [27], [28], a passive device that interconnects inputs and outputs at photonic channel level. At the input ports, the Label Extractors (LE) and Tunable Wavelength Converters (TWCs) [29], [30] control the wavelengths used to transmit data, thus the wavelengths of the input and output channel can differ.…”

Towards 48-fold cabling complexity reduction in large flattened butterfly networks

“…Table I summarizes the properties of C-FBFly compared to current optical DC proposals in terms [25]. A similar method has been proposed for barrier synchronization framework in parallel computers [33]. It achieves all-to-all connectivity by equipping the CPUs with DWDM capable optical transceivers and connecting them together through a multi-stage AWGR network while it eliminates the need for both electrical switches and tunable wavelength converters.…”

Photonic Interconnection Networks for Exascale Computers

“…Figure 7.1 shows the block diagram of the devised optical switch. The central module is an Arrayed Waveguide Grating Router (AWGR) [60,79], a passive device that interconnects inputs and outputs at photonic channel level. At the input ports, the Label Extractor (LE) and the Tunable Wavelength Converters (TWCs) [14,76] control the wavelengths used to transmit data, thus the wavelengths of the input and output channel can differ.…”