Performance modeling of fault-tolerant circuit-switched communication networks

Circuit switching (CS) has been suggested as an efficient switching method for supporting simultaneous communications (such as data, voice, and images) across parallel systems due to its ability to preserve both communication performance and fault-tolerant demands in such systems. In this paper we present an efficient scheme to capture the mean message latency in 2D torus with CS in the presence of faulty components. We have also conducted extensive simulation experiments, the results of which are used to validate the analytical mode

Software-based fault-tolerant routing algorithm in multidimensional networks

Massively parallel computing systems are being built with hundreds or thousands of components such as nodes, links, memories, and connectors. The failure of a component in such systems will not only reduce the computational power but also alter the network's topology. The software-based fault-tolerant routing algorithm is a popular routing to achieve fault-tolerance capability in networks. This algorithm is initially proposed only for two dimensional networks (Suh et al., 2000). Since, higher dimensional networks have been widely employed in many contemporary massively parallel systems; this paper proposes an approach to extend this routing scheme to these indispensable higher dimensional networks. Deadlock and livelock freedom and the performance of presented algorithm, have been investigated for networks with different dimensionality and various fault regions. Furthermore, performance results have been presented through simulation experiments

Analysis of Buffer Arrangements in Low and High Dimensional Networks

Virtual channels have been introduced to enhance the performance of wormhole-switched networks. They are formed by arranging the buffer space dedicated to a given physical channel into multiple parallel buffers that share the physical bandwidth on a demand driven time-multiplexed manner. The question to be answered is: given a fixed amount of finite buffer what is the optimal way to arrange it into virtual channels. There have been few studies attempting to address this issue, however, these studies have so far resorted to simulation experiments and focused on deterministic routing algorithms. In this paper we use analytical performance models to investigate the optimal arrangement of the available buffer space into multiple virtual channels when adaptive routing is used in wormhole-switched k-ary ncubes

A New Approach to Model Virtual Channels

In this paper we present a new approach to model the effect of virtual channel multiplexing in high-speed interconnection networks. Previous studies have used a method proposed by Dally to model the effect of virtual channel multiplexing. His method is based on a Markov process and loses its accuracy as the traffic increases because of the blocking nature of the wormhole-switched networks. Our new approach is based on a finite capacity queue, M/G/1/V. Beside the accuracy that it achieves under low, moderate and high traffic, a main advantage for our new approach is also the simplicity of adapting it to work with different traffic conditions and network setups. The new approach is validated by means of an event driven simulator and a detailed comparison with Dally’s approach is presented

A new modelling approach of wormhole-switched networks with finite buffers

Owing to its simple router design and insensitivity to the message distance, wormhole switching has been employed not only in networks for contemporary multicomputers but also, in networks for clusters of workstations, and more recently in networks for systems-on-chips. Although analytical performance models for wormhole-switched networks have been widely reported in the literature, most of these models have assumed no (or negligible) buffers at a given router in order to ease the derivation of the model. In this paper, we propose a new simple and yet accurate model to capture the effects of finite buffers on the performance of wormhole-switched networks. Simulation experiments demonstrate the validity of the suggested model under various operating conditions

Deep versus Parallel Buffers in Wormhole Switched k-Ary n-Cubes Abstract

Virtual channels have been introduced to enhance the performance of wormhole-switched networks. They are formed by arranging the buffer space dedicated to a given physical channel into multiple parallel buffers that share the physical bandwidth in a demand driven time-multiplexed manner. There have been few attempts to study the optimal arrangement of virtual channels (i.e. given a fixed amount of finite buffer what is the optimal way to arrange it into virtual channels). However, these studies have so fare resorted to simulation experiments and focused on deterministic routing algorithms. In this paper we use analytical performance models to investigate the optimal arrangement of the available buffer space into multiple virtual channels when adaptive routing is used in wormhole-switched k-ary n-cubes. 1

On the probability distribution of busy virtual channels

A major issue in modelling the performance merits of interconnection network is dealing with virtual channels. Some analytical models chose not to deal with this issue at all i.e. one virtual channel per physical channel. More sophisticated models, however, relayed on a method proposed by Dally to capture the effect of arranging the physical channel into many virtual channels. In this study, we investigate the accuracy of Dally’s method and propose an alternative approach to deal with virtual channels in analytical performance modelling. The new method is validated via simulation experiments and results reveal its accuracy under different traffic conditions. 1