Enabling System-Level Modeling of Variation-Induced Faults in Networks-on-Chip

Process Variation (PV) is increasingly threatening the reliability of Networks-on-Chips. Thus, various resilient router designs have been recently proposed and evaluated. However, these evaluations assume random fault distributions, which result in 52%--81% inaccuracy. We propose an accurate circuit-level fault-modeling tool, which can be plugged into any system-level NoC simulator, quantify the system-level impact of PV-induced faults at runtime, pinpoint fault-prone router components that should be protected, and accurately evaluate alternative resilient multi-core designs.GigaScale Systems Research CenterFocus Center Research Program. Focus Center for Circuit & System Solutions. Semiconductor Research Corporation. Interconnect Focus Cente

Parameterizable network-on-chip emulation framework

Networks-on-Chip (NoCs) have been proposed as a promising solution to complex on-chip communication problems. But there is no public accessible HDL synthesizable NoC framework which connects industrial level cores and runs real applications on them. Moreover, many challenging research problems remain unsolved at all levels of design abstraction; design exploration of NoC architecture for applications, scheduling and mapping algorithms, evaluation of switching, topology or routing algorithm for efficient execution of application and optimizing communication cost, area, energy etc Solution to solve the above problem calls for the development of synthesizable, parameterizable NoC Framework that would evaluate and implement the above outstanding research problems and algorithms with minimum ease and flexibility. The proposed NoC Framework has been used to specifically evaluate the following algorithms or variations in architecture: i) Evaluate Switching Algorithms compare latency, congestion, area and power of Wormhole (WH) and Store and Forward (SF) switching, ii) Efficient Router Architecture: Proposed an efficient Virtual Channel architecture with loopback for SF routing is introduced to improve throughput, latency and area, iii) Static routing algorithm: Proposed a simple and efficient routing algorithm called “Mirror Routing” for Torus architectures. This helps in reducing congestion and the routing algorithm is also deadlock free, iv) Adaptive Routing Algorithm: Proposed and evaluated an adaptive routing algorithm for WK topology. The simulation results show Wormhole Routing with better latency than Store and Forward. Area and Power usage is also relatively less for Wormhole Routing. Study on different traffic scenarios with different Virtual Channel architectures in Store and Forward routing shows considerable improvement in latency in Virtual Channel architecture with loopback. Also it is proved that the proposed Mirror Routing algorithm is able to handle a single congestion or fault in routing path. The latency increases with increase in size of Torus structure. The Adaptive routing algorithm proposed for WK Topology results in increase in latency but can be considered in scenarios where the receiver node at the congested link is comparatively slow or when the fault in link is permanent

Design and Evaluation of a Parameterizable NoC Router for FPGAs

The Network-on-Chip (NoC) approach for designing (System-on-Chip) SoCs is currently emerging as an advanced concept for overcoming the scalability and efficiency problems of traditional on-chip interconnection schemes. This thesis addresses the design and evaluation of a parameterizable NoC router for FPGAs. The importance of low area overhead for NoC components is crucial in FPGAs, which have fixed logic and routing resources. We achieve a low area router design through optimizations in switching fabric and dual purpose buffer/connection signals. We propose a component library to increase re-use and allow tailoring of parameters for application specific NoCs of various sizes. A set of experiments were conducted to explore the design space of the proposed NoC router using different values of key router parameters: channel width (flit size), arbitration scheme and IP-core-to-router mapping strategy. Area and latency results from the experiments are presented and analyzed

CAP Bench: a benchmark suite for performance and energy evaluation of low-power many-core processors

International audienceSUMMARY The constant need for faster and more energy-efficient processors has been stimulating the development of new architectures, such as low-power many-core architectures. Researchers aiming to study these architectures are challenged by peculiar characteristics of some components such as Networks-on-Chip and lack of specific tools to evaluate their performance. In this context, the goal of this paper is to present a benchmark suite to evaluate state-of-the-art low-power many-core architectures such as the Kalray MPPA-256 low-power processor, which features 256 compute cores in a single chip. The benchmark was designed and used to highlight important aspects and details that need to be considered when developing parallel applications for emerging low-power many-core architectures. As a result, this paper demonstrates that the benchmark offers a diverse suite of programs with regard to parallel patterns, job types, communication intensity and task load strategies, suitable for a broad understanding of performance and energy consumption of MPPA-256 and upcoming many-core architectures

Comparing energy and latency of asynchronous and synchronous NoCs for embedded SoCs

Journal ArticlePower consumption of on-chip interconnects is a primary concern for many embedded system-on-chip (SoC) applications. In this paper, we compare energy and performance characteristics of asynchronous (clockless) and synchronous network on-chip implementations, optimized for a number of SoC designs. We adapted the COSI-2.0 framework with ORION 2.0 router and wire models for synchronous network generation. Our own tool, ANetGen, specifies the asynchronous network by determining the topology with simulated-annealing and router locations with force-directed placement. It uses energy and delay models from our 65 nm bundled-data router design. SystemC simulations varied traffic burstiness using the self-similar b-model. Results show that the asynchronous network provided lower median and maximum message latency, especially under bursty traffic, and used far less router energy with a slight overhead for the interrouter wires

Reliability-aware and energy-efficient system level design for networks-on-chip

2015 Spring.Includes bibliographical references.With CMOS technology aggressively scaling into the ultra-deep sub-micron (UDSM) regime and application complexity growing rapidly in recent years, processors today are being driven to integrate multiple cores on a chip. Such chip multiprocessor (CMP) architectures offer unprecedented levels of computing performance for highly parallel emerging applications in the era of digital convergence. However, a major challenge facing the designers of these emerging multicore architectures is the increased likelihood of failure due to the rise in transient, permanent, and intermittent faults caused by a variety of factors that are becoming more and more prevalent with technology scaling. On-chip interconnect architectures are particularly susceptible to faults that can corrupt transmitted data or prevent it from reaching its destination. Reliability concerns in UDSM nodes have in part contributed to the shift from traditional bus-based communication fabrics to network-on-chip (NoC) architectures that provide better scalability, performance, and utilization than buses. In this thesis, to overcome potential faults in NoCs, my research began by exploring fault-tolerant routing algorithms. Under the constraint of deadlock freedom, we make use of the inherent redundancy in NoCs due to multiple paths between packet sources and sinks and propose different fault-tolerant routing schemes to achieve much better fault tolerance capabilities than possible with traditional routing schemes. The proposed schemes also use replication opportunistically to optimize the balance between energy overhead and arrival rate. As 3D integrated circuit (3D-IC) technology with wafer-to-wafer bonding has been recently proposed as a promising candidate for future CMPs, we also propose a fault-tolerant routing scheme for 3D NoCs which outperforms the existing popular routing schemes in terms of energy consumption, performance and reliability. To quantify reliability and provide different levels of intelligent protection, for the first time, we propose the network vulnerability factor (NVF) metric to characterize the vulnerability of NoC components to faults. NVF determines the probabilities that faults in NoC components manifest as errors in the final program output of the CMP system. With NVF aware partial protection for NoC components, almost 50% energy cost can be saved compared to the traditional approach of comprehensively protecting all NoC components. Lastly, we focus on the problem of fault-tolerant NoC design, that involves many NP-hard sub-problems such as core mapping, fault-tolerant routing, and fault-tolerant router configuration. We propose a novel design-time (RESYN) and a hybrid design and runtime (HEFT) synthesis framework to trade-off energy consumption and reliability in the NoC fabric at the system level for CMPs. Together, our research in fault-tolerant NoC routing, reliability modeling, and reliability aware NoC synthesis substantially enhances NoC reliability and energy-efficiency beyond what is possible with traditional approaches and state-of-the-art strategies from prior work

An improved non-local awareness of congestion and load balanced algorithm for the communication of on chip 2D mesh-based network

Due to advancements in multi-core design technology, IC (Integrated Circuits) designers have expanded the single chip multi-core design. A privileged way of communication effectively between these multi-cores is a Network on-chip (NoC). Design of an effective routing algorithm capable of routing data to non-congested paths is the most notable research challenge in NoC, by retrieving congestion information of non-local nodes. This research proposed an improved congestion-aware load balancing routing algorithm. Non-local or distant links congestion awareness is done by propagating congestion information via data packets. By counting number of hops from the source node, in the quadrant of the destination node, an intermediate node has been defined, and after the calculation of the least congested route to the intermediate node, this route is also stored in the data packet for source routing. Furthermore, for load balancing network is partitioned into two areas called high congested area (HCA) and low congested area (LCA). For load balancing, from HCA a node in LCA is selected as output for data packets. Comparison of the proposed algorithm is done in the form of average latency, average throughput, power consumption, and scalability analysis under synthetic traffic patterns. Under simulation experiments, it is shown improvement in an average latency and throughput of the proposed algorithm is 31.28% and 5.28% respectively, than existing

HW-SW Emulation Framework for Temperature-Aware Design in MPSoCs

New tendencies envisage Multi-Processor Systems-On-Chip (MPSoCs) as a promising solution for the consumer electronics market. MPSoCs are complex to design, as they must execute multiple applications (games, video), while meeting additional design constraints (energy consumption, time-to-market). Moreover, the rise of temperature in the die for MPSoCs can seriously affect their final performance and reliability. In this paper, we present a new hardware-software emulation framework that allows designers a complete exploration of the thermal behavior of final MPSoC designs early in the design flow. The proposed framework uses FPGA emulation as the key element to model the hardware components of the considered MPSoC platform at multi-megahertz speeds. It automatically extracts detailed system statistics that are used as input to our software thermal library running in a host computer. This library calculates at run-time the temperature of on-chip components, based on the collected statistics from the emulated system and the final floorplan of the MPSoC. This enables fast testing of various thermal management techniques. Our results show speed-ups of three orders of magnitude compared to cycle-accurate MPSoC simulator