Memory System for a Dynamically Adaptable Pixel Stream Architecture

International audienceNowadays, embedded vision systems have to face new hard requirements involved by modern applications: realtime processing of high resolution images issued by multiple image sensors. Recently, a new adaptable ring-based interconnection network on chip has been proposed. Based on adaptive datapath, it allows handling of multiple parallel pixel streams. In this paper, we present a new hierarchical memory system proposed for this adaptable ring-based architecture. The design of its different levels is discussed and we show how the memory system adapts dynamically with respect to the datapath and data access management in the interconnection network. We also present the timing performance and area occupation measured on an FPGA prototype

High-level services for networks-on-chip

Future technology trends envision that next-generation Multiprocessors Systems-on- Chip (MPSoCs) will be composed of a combination of a large number of processing and storage elements interconnected by complex communication architectures. Communication and interconnection between these basic blocks play a role of crucial importance when the number of these elements increases. Enabling reliable communication channels between cores becomes therefore a challenge for system designers. Networks-on-Chip (NoCs) appeared as a strategy for connecting and managing the communication between several design elements and IP blocks, as required in complex Systems-on-Chip (SoCs). The topic can be considered as a multidisciplinary synthesis of multiprocessing, parallel computing, networking, and on- chip communication domains. Networks-on-Chip, in addition to standard communication services, can be employed for providing support for the implementation of system-level services. This dissertation will demonstrate how high-level services can be added to an MPSoC platform by embedding appropriate hardware/software support in the network interfaces (NIs) of the NoC. In this dissertation, the implementation of innovative modules acting in parallel with protocol translation and data transmission in NIs is proposed and evaluated. The modules can support the execution of the high-level services in the NoC at a relatively low cost in terms of area and energy consumption. Three types of services will be addressed and discussed: security, monitoring, and fault tolerance. With respect to the security aspect, this dissertation will discuss the implementation of an innovative data protection mechanism for detecting and preventing illegal accesses to protected memory blocks and/or memory mapped peripherals. The second aspect will be addressed by proposing the implementation of a monitoring system based on programmable multipurpose monitoring probes aimed at detecting NoC internal events and run-time characteristics. As last topic, new architectural solutions for the design of fault tolerant network interfaces will be presented and discussed

Optical network-on-chip architectures and designs

As indicated in the latest version of ITRS roadmap, optical wiring is a viable interconnection technology for future SoC/SiC/SiP designs that can provide broad band data transfer rates unmatchable by the existing metal/low-k dielectric interconnects. In this dissertation study, a set of different optical interconnection architectures are presented for future on-chip optical micro-networks. Three Optical Network-on-Chip (ONoC) architectures, i.e., Wavelength Routing Optical Network-on-Chip (WRON), Redundant Wavelength Routed Optical Network (RDWRON) and Recursive Wavelength Routed Optical Network (RCWRON) are proposed. They are fully connected networks designed based on passive switching Microring Resonator (MRR) optical switches. Given enough different routing optical wavelengths, between any two nodes in the system a bi-directional communication channel can be built. WRON, RDWRON and RCWRON share the similar network structure with different specialties that fit to different applications. A new topology of packet switching NoC architecture, i.e., Quartered Recursive Diagonal Torus (QRDT) is proposed. It is designed by overlaying diagonal torus. Due to its small diameter and rich routing recourses, QRDT leads to highly scalable NoCs. By combining WRON\u27s interconnection property and QRDT\u27s network topology, a group of 2D-Torus based Packet Switching ONoC (TON) architectures is proposed. The TON is further refined to a generalized open-topology ONoC architecture, called Generalized 2D-Torus-based Optical Network-on-Chip (GTON). The communication protocol in TON is packet switching. The advantages of GTON stem from Wavelength Division Multiplexing (WDM), Direct Optical Channel (DOC) and MRR passive switching. As result, GTON architecture is highly scalable, has an ultra-high bandwidth, consumes a low power, and supports fault-tolerant routing. The work includes other issues such as channel design, analyses of the transmission power loss and the buffer

Architectural Exploration and Design Methodologies of Photonic Interconnection Networks

Photonic technology is becoming an increasingly attractive solution to the problems facing today's electronic chip-scale interconnection networks. Recent progress in silicon photonics research has enabled the demonstration of all the necessary optical building blocks for creating extremely high-bandwidth density and energy-efficient links for on- and off-chip communications. From the feasibility and architecture perspective however, photonics represents a dramatic paradigm shift from traditional electronic network designs due to fundamental differences in how electronics and photonics function and behave. As a result of these differences, new modeling and analysis methods must be employed in order to properly realize a functional photonic chip-scale interconnect design. In this work, we present a methodology for characterizing and modeling fundamental photonic building blocks which can subsequently be combined to form full photonic network architectures. We also describe a set of tools which can be utilized to assess the physical-layer and system-level performance properties of a photonic network. The models and tools are integrated in a novel open-source design and simulation environment called PhoenixSim. Next, we leverage PhoenixSim for the study of chip-scale photonic networks. We examine several photonic networks through the synergistic study of both physical-layer metrics and system-level metrics. This holistic analysis method enables us to provide deeper insight into architecture scalability since it considers insertion loss, crosstalk, and power dissipation. In addition to these novel physical-layer metrics, traditional system-level metrics of bandwidth and latency are also obtained. Lastly, we propose a novel routing architecture known as wavelength-selective spatial routing. This routing architecture is analogous to electronic virtual channels since it enables the transmission of multiple logical optical channels through a single physical plane (i.e. the waveguides). The available wavelength channels are partitioned into separate groups, and each group is routed independently in the network. Each partition is spectrally multiplexed, as opposed to temporally multiplexed in the electronic case. The wavelength-selective spatial routing technique benefits network designers by provider lower contention and increased path diversity

Driving the Network-on-Chip Revolution to Remove the Interconnect Bottleneck in Nanoscale Multi-Processor Systems-on-Chip

The sustained demand for faster, more powerful chips has been met by the availability of chip manufacturing processes allowing for the integration of increasing numbers of computation units onto a single die. The resulting outcome, especially in the embedded domain, has often been called SYSTEM-ON-CHIP (SoC) or MULTI-PROCESSOR SYSTEM-ON-CHIP (MP-SoC). MPSoC design brings to the foreground a large number of challenges, one of the most prominent of which is the design of the chip interconnection. With a number of on-chip blocks presently ranging in the tens, and quickly approaching the hundreds, the novel issue of how to best provide on-chip communication resources is clearly felt. NETWORKS-ON-CHIPS (NoCs) are the most comprehensive and scalable answer to this design concern. By bringing large-scale networking concepts to the on-chip domain, they guarantee a structured answer to present and future communication requirements. The point-to-point connection and packet switching paradigms they involve are also of great help in minimizing wiring overhead and physical routing issues. However, as with any technology of recent inception, NoC design is still an evolving discipline. Several main areas of interest require deep investigation for NoCs to become viable solutions: • The design of the NoC architecture needs to strike the best tradeoff among performance, features and the tight area and power constraints of the onchip domain. • Simulation and verification infrastructure must be put in place to explore, validate and optimize the NoC performance. • NoCs offer a huge design space, thanks to their extreme customizability in terms of topology and architectural parameters. Design tools are needed to prune this space and pick the best solutions. • Even more so given their global, distributed nature, it is essential to evaluate the physical implementation of NoCs to evaluate their suitability for next-generation designs and their area and power costs. This dissertation performs a design space exploration of network-on-chip architectures, in order to point-out the trade-offs associated with the design of each individual network building blocks and with the design of network topology overall. The design space exploration is preceded by a comparative analysis of state-of-the-art interconnect fabrics with themselves and with early networkon- chip prototypes. The ultimate objective is to point out the key advantages that NoC realizations provide with respect to state-of-the-art communication infrastructures and to point out the challenges that lie ahead in order to make this new interconnect technology come true. Among these latter, technologyrelated challenges are emerging that call for dedicated design techniques at all levels of the design hierarchy. In particular, leakage power dissipation, containment of process variations and of their effects. The achievement of the above objectives was enabled by means of a NoC simulation environment for cycleaccurate modelling and simulation and by means of a back-end facility for the study of NoC physical implementation effects. Overall, all the results provided by this work have been validated on actual silicon layout

Cycle-accurate evaluation of reconfigurable photonic networks-on-chip

There is little doubt that the most important limiting factors of the performance of next-generation Chip Multiprocessors (CMPs) will be the power efficiency and the available communication speed between cores. Photonic Networks-on-Chip (NoCs) have been suggested as a viable route to relieve the off- and on-chip interconnection bottleneck. Low-loss integrated optical waveguides can transport very high-speed data signals over longer distances as compared to on-chip electrical signaling. In addition, with the development of silicon microrings, photonic switches can be integrated to route signals in a data-transparent way. Although several photonic NoC proposals exist, their use is often limited to the communication of large data messages due to a relatively long set-up time of the photonic channels. In this work, we evaluate a reconfigurable photonic NoC in which the topology is adapted automatically (on a microsecond scale) to the evolving traffic situation by use of silicon microrings. To evaluate this system's performance, the proposed architecture has been implemented in a detailed full-system cycle-accurate simulator which is capable of generating realistic workloads and traffic patterns. In addition, a model was developed to estimate the power consumption of the full interconnection network which was compared with other photonic and electrical NoC solutions. We find that our proposed network architecture significantly lowers the average memory access latency (35% reduction) while only generating a modest increase in power consumption (20%), compared to a conventional concentrated mesh electrical signaling approach. When comparing our solution to high-speed circuit-switched photonic NoCs, long photonic channel set-up times can be tolerated which makes our approach directly applicable to current shared-memory CMPs

Performance evaluation of multi-core multi-cluster architecture

A multi-core cluster is a cluster composed of numbers of nodes where each node has a number of processors, each with more than one core within each single chip. Cluster nodes are connected via an interconnection network. Multi-cored processors are able to achieve higher performance without driving up power consumption and heat, which is the main concern in a single-core processor. A general problem in the network arises from the fact that multiple messages can be in transit at the same time on the same network links. This paper considers the communication latencies of a multi-core multi-cluster architecture will be investigated using simulation experiments and measurements under various working conditions