text: With technology scaling down, hundreds and thousands processing elements (PEs) can be integrated on a single chip. Network-on-chip (NoC) has been proposed as an efficient solution to handle this distinctive challenge. In this thesis, we have explored the high performance NoC design for MPSoC and CMP structures from the performance modeling in the offline design phase to the routing algorithm and NoC architecture optimization. More specifically, we first deal with the issue of how to estimate an NoC design fast and accurately in the synthesis inner loop. For this purpose, we propose a machine learning based latency regression model to evaluate the NoC designs with respect to different configurations. Then, for high performance NoC designs, we tackle one of the most important problems, i.e., the routing algorithms design. For avoiding temperature hotspots, a thermal-aware routing algorithm is proposed to achieve an even temperature profile for application-specific Network-on-chips (NoCs). For improving the reliability, a routing algorithm to achieve maximum performance under fault is proposed. Finally, in the architecture level, we propose two new NoC structures using bi-directional links for the performance optimization. In particular, we propose a flit-level speedup scheme to enhance the network-on-chip(NoC) performance utilizing bidirectional channels. We also propose a flexible NoC architecture which takes advantage of a dynamic distributed routing algorithm and improves the NoC communication performance with moderate energy overhead. From the simulation results on both synthetic traffic and real workload traces, significant performance improvement in terms of latency and throughput can be achieved.
  @cite_109: Process scaling has given designers billions of transistors to work with. As feature sizes near the atomic scale, extensive variation and wearout inevitably make margining uneconomical or impossible. The ElastIC project seeks to address this by creating a large-scale chip-multiprocessor that can self-diagnose, adapt, and heal. Creating large, flexible designs in this environment naturally lends itself to the repetitive nature of network-on-chip (NoC), but the loss of a single link or router will result in complete network failure. In this work we present Vicis, an ElastIC-style NoC that can tolerate the loss of many network components due to wearout induced hard faults. Vicis uses the inherent redundancy in the network and its routers in order to maintain correct operation while incurring a much lower area overhead than previously proposed N-modular redundancy (NMR) based solutions. Each router has a built-in-self-test (BIST) that diagnoses the locations of hard fault and runs a number of algorithms to best use ECC, port swapping, and a crossbar bypass bus to mitigate them. The routers work together to run distributed algorithms to solve network-wide problems as well, protecting the networking against critical failures in individual routers. In this work we show that with stuck-at fault rates as high as 1 in 2000 gates, Vicis will continue to operate with approximately half of its routers still functional and communicating.
  @cite_52: In this paper, we utilize a novel fluidity concept to analyze and develop routing algorithms in network-on-chip for congestion avoidance and relief. We develop a new model to capture congestion information which improves the performance of routing algorithms. Comparisons of algorithms using our model consistently outperform the original algorithms themselves.
  @cite_106: Technology scaling imposes an ever increasing temperature stress on digital circuit design due to transistor density, especially on highly integrated systems, such as Multi-Processor Systems-on-Chip (MPSoCs). Therefore,temperature-aware design is mandatory and should be performed at the early design stages. In this paper we present a novel hardware infrastructure to provide thermal control of MPSoC architectures, which is based on exploiting the No interconnects of the baseline system as an active component to communicate and coordinate between temperature sensors scattered around the chip, in order to globally monitor the actual temperature. Then, a thermal management unit and clock frequency controllers adjust the frequency and voltage of the processing elements according to the temperature requirements at run-time. We show experimental results of the infrastructure to implement effective global temperature control policies for a real-life 4-core MPSoC,emulated on an FPGA-based emulation framework.
  @cite_50: With the ability to integrate a large number of cores on a single chip, research into on-chip networks to facilitate communication becomes increasingly important. On-chip networks seek to provide a scalable and high-bandwidth communication substrate for multi-core and many-core architectures. High bandwidth and low latency within the on-chip network must be achieved while fitting within tight area and power budgets. In this lecture, we examine various fundamental aspects of on-chip network design and provide the reader with an overview of the current state-of-the-art research in this field. Table of Contents: Introduction Interface with System Architecture Topology Routing Flow Control Router Microarchitecture Conclusions
  @cite_93: 
  @cite_34: In this paper, a routing model for minimizing hot spots in the network on chip (NOC) is presented. The model makes use of AntNet routing algorithm which is based on Ant colony. Using this algorithm, which we call AntNet routing algorithm, heavy packet traffics are distributed on the chip minimizing the occurrence of hot spots. To evaluate the efficiency of the scheme, the proposed algorithm was compared to the XY, Odd- Even, and DyAD routing models. The simulation results show that in realistic (Transpose) traffic as well as in heavy packet traffic, the proposed model has less average delay and peak power compared to the other routing models. In addition, the maximum temperature in the proposed algorithm is less than those of the other routing algorithms.
summary: Since the power consumption of the routers is as significant as the processor core, the thermal constraint should also be addressed in the routing algorithm design. There have been a lot of works on NoC routing algorithms for various purposes including low power routing @cite_106 , fault-tolerant routing @cite_109 and congestion avoidance routing to improve latency @cite_52 . However, there are only a few works @cite_34 @cite_50 @cite_93 taking temperature issue into account.