A General, Fault tolerant, Adaptive, Deadlock-free Routing Protocol for Network-on-chip

The paper presents a topology-agnostic greedy protocol for network-on-chip routing. The proposed routing algorithm can tolerate any number of permanent faults, and is proven to be deadlock-free. We introduce a specialized variant of the algorithm, which is optimized for 2D mesh networks, both flat and wireless. The adaptiveness and minimality of several variants this algorithm are analyzed through graph-based simulations.Comment: Presented at 11th International Workshop on Network on Chip Architectures (NoCArc 2018

A General, Fault tolerant, Adaptive, Deadlock-free Routing Protocol for Network-on-chip

The paper presents a topology-agnostic greedy protocol for network-on-chip routing. The proposed routing algorithm can tolerate any number of permanent faults, and is proven to be deadlock-free. We introduce a specialized variant of the algorithm, which is optimized for 2D mesh networks, both flat and wireless. The adaptiveness and minimality of several variants this algorithm are analyzed through graph-based simulations.Comment: Presented at 11th International Workshop on Network on Chip Architectures (NoCArc 2018

Physical-aware link allocation and route assignment for chip multiprocessing

The architecture definition, design, and validation of the interconnect networks is a key step in the design of modern on-chip systems. This paper proposes a mathematical formulation of the problem of simultaneously defining the topology of the network and the message routes for the traffic among the processing elements of the system. The solution of the problem meets the physical and performance constraints defined by the designer. The method guarantees that the generated solution is deadlock free. It is also capable of automatically discovering topologies that have been previously used in industrial systems. The applicability of the method has been validated by solving realistic size interconnect networks modeling the typical multiprocessor systems.Peer ReviewedPostprint (published version

Fault tolerant routing algorithm for fully- and partially-defective NoC switches

Recently network-on-chip (NoC) has become a broad topic of research and development and is going to displace bus and crossbar approaches for Systems-on-chip interconnection. NoCs provide the needs of an efficient communication infrastructure of complex SoC. In order to meet the communication requirements even in presence of faults, fault tolerant routing algorithms become one of the most dominant issues for NoC systems. There has been significant works on fault tolerant routing algorithms for NoCs which mostly support only fully defective switches, but in this thesis, a new deadlock and live-lock free fault tolerant routing algorithm that tolerates fully- and partially-defective NoC switches will be introduced. The proposed algorithm is an enhancement of the available region-based approach for NoCs. The novelty of our approach is that link failures are modeled as semi-faulty switches and as a result the faulty region is smaller and less healthy switches are deactivated. The algorithm does not need any virtual channel. In addition, the routing algorithm does not require routing table in every switch. The performance comparison shows the advantages of the proposed algorithm with state-of-the-art fault tolerant routing algorithms. Since our algorithm has less deactivated switches it has always higher throughput and less latency

Design of TSV-sharing topologies for cost-effective 3D networks-on-chip

The Through-Silicon Via (TSV) technology has led to major breakthroughs in 3D stacking by providing higher speed and bandwidth, as well as lower power dissipation for the inter-layer communication. However, the current TSV fabrication suffers from a considerable area footprint and yield loss. Thus, it is necessary to restrict the number of TSVs in order to design cost-effective 3D on-chip networks. This critical issue can be addressed by clustering the network such that all of the routers within each cluster share a single TSV pillar for the vertical packet transmission. In some of the existing topologies, additional cluster routers are augmented into the mesh structure to handle the shared TSVs. However, they impose either performance degradation or power/area overhead to the system. Furthermore, the resulting architecture is no longer a mesh. In this paper, we redefine the clusters by replacing some routers in the mesh with the cluster routers, such that the mesh structure is preserved. The simulation results demonstrate a better equilibrium between performance and cost, using the proposed models

A ROUTING ALGORITHM AND A ROUTER ARCHITECTURE FOR 3D NOC

In recent years, the enhancement of microchip technologies has enabled large scale Systems-on-Chip (SoC). Due to sharp increase in number of processing elements, SoC faces various challenges in design and testing.  Network on Chip (NoC) is an alternative technology to overcome the challenges in SoC design and testing. NoC emerged as a key architecture that allows one to optimize the parameters like power and area. In spite of its applications, NoC faces some real time challenges like designing an optimum topology, routing scheme and application mappings. In this paper, we address the main three issues on NoC, namely, designing of an optimal topology, routing algorithm and a router design for the topology. First, we propose a topology and a routing algorithm. We prove that our recursive network topology is Hamiltonian connected and we propose an algorithm for data packet transmissions, which is free from cyclic deadlocks and the algorithm maximizes the congestion factor. Our experimental results show that the proposed topology gives better performance in terms of average latency and power than the other topologies. Finally, we propose a router architecture for our 3D-NoC. The router architecture is based on shared buffers. Also, our experimental results indicate that the proposed router architecture consumes less area and power than the Virtual Channel architecture

Automatic synthesis and optimization of chip multiprocessors

The microprocessor technology has experienced an enormous growth during the last decades. Rapid downscale of the CMOS technology has led to higher operating frequencies and performance densities, facing the fundamental issue of power dissipation. Chip Multiprocessors (CMPs) have become the latest paradigm to improve the power-performance efficiency of computing systems by exploiting the parallelism inherent in applications. Industrial and prototype implementations have already demonstrated the benefits achieved by CMPs with hundreds of cores.CMP architects are challenged to take many complex design decisions. Only a few of them are:- What should be the ratio between the core and cache areas on a chip?- Which core architectures to select?- How many cache levels should the memory subsystem have?- Which interconnect topologies provide efficient on-chip communication?These and many other aspects create a complex multidimensional space for architectural exploration. Design Automation tools become essential to make the architectural exploration feasible under the hard time-to-market constraints. The exploration methods have to be efficient and scalable to handle future generation on-chip architectures with hundreds or thousands of cores.Furthermore, once a CMP has been fabricated, the need for efficient deployment of the many-core processor arises. Intelligent techniques for task mapping and scheduling onto CMPs are necessary to guarantee the full usage of the benefits brought by the many-core technology. These techniques have to consider the peculiarities of the modern architectures, such as availability of enhanced power saving techniques and presence of complex memory hierarchies.This thesis has several objectives. The first objective is to elaborate the methods for efficient analytical modeling and architectural design space exploration of CMPs. The efficiency is achieved by using analytical models instead of simulation, and replacing the exhaustive exploration with an intelligent search strategy. Additionally, these methods incorporate high-level models for physical planning. The related contributions are described in Chapters 3, 4 and 5 of the document.The second objective of this work is to propose a scalable task mapping algorithm onto general-purpose CMPs with power management techniques, for efficient deployment of many-core systems. This contribution is explained in Chapter 6 of this document.Finally, the third objective of this thesis is to address the issues of the on-chip interconnect design and exploration, by developing a model for simultaneous topology customization and deadlock-free routing in Networks-on-Chip. The developed methodology can be applied to various classes of the on-chip systems, ranging from general-purpose chip multiprocessors to application-specific solutions. Chapter 7 describes the proposed model.The presented methods have been thoroughly tested experimentally and the results are described in this dissertation. At the end of the document several possible directions for the future research are proposed