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Mohamed Ould-khaoua - One of the best experts on this subject based on the ideXlab platform.
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Performance modeling of n-dimensional mesh networks
Performance Evaluation, 2010Co-Authors: Pedram Rajabzadeh, Hamid Sarbazi-azad, Hamid-reza Zarandi, Ebrahim Khodaie, Hashem Hashemi-najafabadi, Mohamed Ould-khaouaAbstract:Mesh-based interconnection networks are the most popular inter-processor communication infrastructures used in current parallel supercomputers. Although many analytical models of n-D torus interconnection networks have been reported in the literature over the last decade, few analytical models have been proposed for the 2-D mesh case (and not for the general n-D mesh network) using inaccurate approximations as they have not fully incorporated the asymmetry effects of the mesh topology, in order to reduce the model complexity. There has not been reported, to the best of our knowledge, a performance model that can deal with the n-D mesh network. To fill this gap, in this paper, we propose the first analytical performance model of the n-D mesh using adaptive wormhole routing. To this end, we calculate the exact traffic rates over different network channels and determine the average Message Latency by averaging over the Message Latency values corresponding to all possible source-destination pairs of nodes in the network. Simulation results show that the proposed model can predict the Message Latency fairly accurately under various working conditions.
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An Analytical Model for Torus Networks in the Presence of Batch Message Arrivals with Hot-spot Destinations
International Journal of Automation and Computing, 2009Co-Authors: Geyong Min, Mohamed Ould-khaoua, Hao YinAbstract:Interconnection networks are hardware fabrics supporting communications between individual processors in multicomputers. The low-dimensional k-ary n-cubes (or torus) with adaptive wormhole switching have attracted significant research efforts to construct high-performance interconnection networks in contemporary multi-computers. The arrival process and destination distribution of Messages have great effects on network performance. With the aim of capturing the characteristics of the realistic traffic pattern and obtaining a deep understanding of the performance behaviour of interconnection networks, this paper presents an analytical model to investigate the Message Latency in adaptive-routed wormhole-switched torus networks where there exists hot-spot nodes and the Message arrivals follow a batch arrival process. Each generated Message has a given probability to be directed to the hot-spot node. The average degree of virtual channel multiplexing is computed by the GE/G/1/V queueing system with finite buffer capacity. We compare analytical results of Message Latency with those obtained through the simulation experiments in order to validate the accuracy of the derived model.
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AN ANALYTICAL COMPARISON OF THE SPIDERGON AND RECTANGULAR MESH NoCs
Journal of Interconnection Networks, 2009Co-Authors: Mahmoud Moadeli, Ali Shahrabi, Wim Vanderbauwhede, Mohamed Ould-khaouaAbstract:Networks on chip (NoC) emerged as a structured and scalable communication medium for development of future Systems-on-Chip (SoC). Due to its unique features in terms of scalability and ease of synthesis, the (rectangular) mesh topology is regarded as an appropriate candidate for on-chip network development. On the other hand, the Spidergon NoC has been proposed as an alternative topology to realize cost effective multi-processor SoC (MPSoC) development. This paper presents analytical models of the average Message Latency and network throughput for both rectangular mesh and the Spidergon NoC employing wormhole switching. For each model, the validity of the analysis is verified by comparing the analytical model against the results produced by a discrete event simulator. Using the developed models, we then compare these topologies from different perspectives including manufacturing issues, Message Latency and network throughput.
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A queueing model for predicting Message Latency in uni-directional k-ary n-cubes with deterministic routing and non-uniform traffic
Cluster Computing, 2007Co-Authors: S. Loucif, Mohamed Ould-khaoua, Geyong MinAbstract:The interconnection network is one of the key architectural components in any parallel computer. The distribution of the traffic injected into the network is among the factors that greatly influences network performance. The uniform traffic pattern has been adopted in many existing network performance evaluation studies due to the tractability of the resulting analytical modelling approach. However, many real applications exhibit non-uniform traffic patterns such as hot-spot traffic. K -ary n -cubes have been the mostly widely used in the implementation of practical parallel systems. Extensive research studies have been conducted on the performance modelling and evaluation of these networks. Nonetheless, most of these studies have been confined to uniform traffic distributions and have been based on software simulation. The present paper proposes a new stochastic model to predict Message Latency in k-ary n-cubes with deterministic routing in the presence of hot-spot traffic. The model has been validated through simulation experiments and has shown a close agreement with simulation results.
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Message Latency in hypercubic computer networks with the bursty traffic pattern
Computers & Electrical Engineering, 2004Co-Authors: Geyong Min, Mohamed Ould-khaouaAbstract:Abstract An interconnection network is a crucial component of parallel computers because the overall system performance is very sensitive to the Latency of Messages delivered by the network to communicate among collaborating processors. This paper presents an analytical performance model to calculate Message Latency in circuit-switched hypercubic networks in the presence of bursty traffic pattern, which is a typical scenario for multimedia applications. A Message in circuit switching may need a number of connection attempts before successfully setting up a path from source to destination. The proposed model uses the approach of superposing infinite bursty traffic streams to capture the effective traffic entering the network from a source node, which includes the traffic generated by the source and those due to many connection attempts. Results obtained from simulation experiments confirm that the proposed model exhibits a good degree of accuracy for various network sizes and under different operating conditions.
S. Loucif - One of the best experts on this subject based on the ideXlab platform.
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EUROCON - Clustering and Message distance trade-offs in torus-based Networks-on-Chip
Eurocon 2013, 2013Co-Authors: S. LoucifAbstract:Low-dimensional k-ary n-cubes were the most popular topologies in parallel computers, and they are still gaining a great interest in the context of on-chip networks. Clustered networks have been suggested to further reduce the diameter of low-dimensional k-ary n-cubes such as mesh and torus. This paper studies the performance merits of clustering with torus topology in terms of average Message Latency, throughput, and power consumption. Results of this study reveal that clustering increases implementation costs of the torus, the power consumption of the clustered-torus router is higher than that of the torus router under all traffic conditions. In terms of Message Latency and throughput, clustering degrades the performance of torus under uniform random traffic pattern. The torus can benefit from clustering only under high degree of communication locality.
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A queueing model for predicting Message Latency in uni-directional k-ary n-cubes with deterministic routing and non-uniform traffic
Cluster Computing, 2007Co-Authors: S. Loucif, Mohamed Ould-khaoua, Geyong MinAbstract:The interconnection network is one of the key architectural components in any parallel computer. The distribution of the traffic injected into the network is among the factors that greatly influences network performance. The uniform traffic pattern has been adopted in many existing network performance evaluation studies due to the tractability of the resulting analytical modelling approach. However, many real applications exhibit non-uniform traffic patterns such as hot-spot traffic. K -ary n -cubes have been the mostly widely used in the implementation of practical parallel systems. Extensive research studies have been conducted on the performance modelling and evaluation of these networks. Nonetheless, most of these studies have been confined to uniform traffic distributions and have been based on software simulation. The present paper proposes a new stochastic model to predict Message Latency in k-ary n-cubes with deterministic routing in the presence of hot-spot traffic. The model has been validated through simulation experiments and has shown a close agreement with simulation results.
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The impact of virtual channel allocation on the performance of deterministic wormhole-routed k-ary n-cubes
Simulation Modelling Practice and Theory, 2002Co-Authors: S. Loucif, Mohamed Ould-khaouaAbstract:Abstract Virtual channels yield significant improvement in the performance of wormhole-routed networks as they can greatly reduce Message blocking over network resources. K -ary n -cubes with deterministic routing have been widely analysed using analytical modelling tools. Most existing models, however, have either entirely ignored the effects of virtual channel multiplexing or have not considered the impact of virtual channels allocation on Message Latency. This paper discusses two different organisations of virtual channels in k -ary n -cubes, resulting in two deterministic routing algorithms. It then proposes an analytical model to compute Message Latency for the two routing algorithms. The proposed model is used in a case study to demonstrate the sensitivity of network Latency to the way virtual channels are allocated to Messages.
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Euro-Par - An Analytical Model of Deterministic Routing in the Presence of Hot-Spot Traffic
Euro-Par 2001 Parallel Processing, 2001Co-Authors: S. Loucif, Mohamed Ould-khaouaAbstract:Analytical models of deterministic routing in common wormhole-routed networks have been widely reported in the literature. However, all these models have been discussed for the uniform traffic pattern. This paper presents the first analytical model of deterministic routing in the hypercube in the presence of hot-spot traffic. Simulation results confirm that the proposed model predicts Message Latency with a reasonable degree of accuracy under different traffic conditions.
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Message Latency in k-ary n-cubes with hop-based routing
IEE Proceedings - Computers and Digital Techniques, 2001Co-Authors: S. Loucif, Hamid Sarbazi-azad, Mohamed Ould-khaouaAbstract:Many adaptive routing algorithms for wormhole-routed k-ary n-cubes have been proposed to overcome the performance limitations of deterministic routing. However, before such routing schemes can be successfully incorporated in future practical multicomputers, it is necessary to develop a clear understanding of the factors that affect their potential performance. Boppanna and Chalasani have recently proposed a routing algorithm (referred to as hop-based routing) that achieves full adaptivity in wormhole-routed k-ary n-cubes using a hop-based scheme borrowed from traditional store-and forward networks. A new analytical model is prepared to compute Message Latency in k-ary n-cubes with hop-based routing. Results from simulation experiments reveal that the proposed model exhibits a good degree of accuracy in predicting Message Latency.
Toby Moncaster - One of the best experts on this subject based on the ideXlab platform.
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SIGCOMM - Silo: Predictable Message Latency in the Cloud
Proceedings of the 2015 ACM Conference on Special Interest Group on Data Communication, 2015Co-Authors: Keon Jang, Justine Sherry, Hitesh Ballani, Toby MoncasterAbstract:Many cloud applications can benefit from guaranteed Latency for their network Messages, however providing such predictability is hard, especially in multi-tenant datacenters. We identify three key requirements for such predictability: guaranteed network bandwidth, guaranteed packet delay and guaranteed burst allowance. We present Silo, a system that offers these guarantees in multi-tenant datacenters. Silo leverages the tight coupling between bandwidth and delay: controlling tenant bandwidth leads to deterministic bounds on network queuing delay. Silo builds upon network calculus to place tenant VMs with competing requirements such that they can coexist. A novel hypervisor-based policing mechanism achieves packet pacing at sub-microsecond granularity, ensuring tenants do not exceed their allowances. We have implemented a Silo prototype comprising a VM placement manager and a Windows filter driver. Silo does not require any changes to applications, guest OSes or network switches. We show that Silo can ensure predictable Message Latency for cloud applications while imposing low overhead.
Keon Jang - One of the best experts on this subject based on the ideXlab platform.
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SIGCOMM - Silo: Predictable Message Latency in the Cloud
Proceedings of the 2015 ACM Conference on Special Interest Group on Data Communication, 2015Co-Authors: Keon Jang, Justine Sherry, Hitesh Ballani, Toby MoncasterAbstract:Many cloud applications can benefit from guaranteed Latency for their network Messages, however providing such predictability is hard, especially in multi-tenant datacenters. We identify three key requirements for such predictability: guaranteed network bandwidth, guaranteed packet delay and guaranteed burst allowance. We present Silo, a system that offers these guarantees in multi-tenant datacenters. Silo leverages the tight coupling between bandwidth and delay: controlling tenant bandwidth leads to deterministic bounds on network queuing delay. Silo builds upon network calculus to place tenant VMs with competing requirements such that they can coexist. A novel hypervisor-based policing mechanism achieves packet pacing at sub-microsecond granularity, ensuring tenants do not exceed their allowances. We have implemented a Silo prototype comprising a VM placement manager and a Windows filter driver. Silo does not require any changes to applications, guest OSes or network switches. We show that Silo can ensure predictable Message Latency for cloud applications while imposing low overhead.
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Silo : Predictable Message Latency in the Cloud
Sigcomm 2015, 2015Co-Authors: Keon Jang, Justine SherryAbstract:Many cloud applications can benefit from guaranteed Latency for their network Messages, however providing such pre- dictability is hard, especially in multi-tenant datacenters.We identify three key requirements for such predictability: guar- anteed network bandwidth, guaranteed packet delay and guar- anteed burst allowance. We present Silo, a system that of- fers these guarantees in multi-tenant datacenters. Silo lever- ages the tight coupling between bandwidth and delay: con- trolling tenant bandwidth leads to deterministic bounds on network queuing delay. Silo builds upon network calculus to place tenant VMs with competing requirements such that they can coexist. A novel hypervisor-based policing mecha- nism achieves packet pacing at sub-microsecond granularity, ensuring tenants do not exceed their allowances. We have implemented a Silo prototype comprising a VM placement manager and a Windows filter driver. Silo does not require any changes to applications, guest OSes or network switches. We show that Silo can ensure predictable Message Latency for cloud applications while imposing low overhead.
Geyong Min - One of the best experts on this subject based on the ideXlab platform.
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An Analytical Model for Torus Networks in the Presence of Batch Message Arrivals with Hot-spot Destinations
International Journal of Automation and Computing, 2009Co-Authors: Geyong Min, Mohamed Ould-khaoua, Hao YinAbstract:Interconnection networks are hardware fabrics supporting communications between individual processors in multicomputers. The low-dimensional k-ary n-cubes (or torus) with adaptive wormhole switching have attracted significant research efforts to construct high-performance interconnection networks in contemporary multi-computers. The arrival process and destination distribution of Messages have great effects on network performance. With the aim of capturing the characteristics of the realistic traffic pattern and obtaining a deep understanding of the performance behaviour of interconnection networks, this paper presents an analytical model to investigate the Message Latency in adaptive-routed wormhole-switched torus networks where there exists hot-spot nodes and the Message arrivals follow a batch arrival process. Each generated Message has a given probability to be directed to the hot-spot node. The average degree of virtual channel multiplexing is computed by the GE/G/1/V queueing system with finite buffer capacity. We compare analytical results of Message Latency with those obtained through the simulation experiments in order to validate the accuracy of the derived model.
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A queueing model for predicting Message Latency in uni-directional k-ary n-cubes with deterministic routing and non-uniform traffic
Cluster Computing, 2007Co-Authors: S. Loucif, Mohamed Ould-khaoua, Geyong MinAbstract:The interconnection network is one of the key architectural components in any parallel computer. The distribution of the traffic injected into the network is among the factors that greatly influences network performance. The uniform traffic pattern has been adopted in many existing network performance evaluation studies due to the tractability of the resulting analytical modelling approach. However, many real applications exhibit non-uniform traffic patterns such as hot-spot traffic. K -ary n -cubes have been the mostly widely used in the implementation of practical parallel systems. Extensive research studies have been conducted on the performance modelling and evaluation of these networks. Nonetheless, most of these studies have been confined to uniform traffic distributions and have been based on software simulation. The present paper proposes a new stochastic model to predict Message Latency in k-ary n-cubes with deterministic routing in the presence of hot-spot traffic. The model has been validated through simulation experiments and has shown a close agreement with simulation results.
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Message Latency in hypercubic computer networks with the bursty traffic pattern
Computers & Electrical Engineering, 2004Co-Authors: Geyong Min, Mohamed Ould-khaouaAbstract:Abstract An interconnection network is a crucial component of parallel computers because the overall system performance is very sensitive to the Latency of Messages delivered by the network to communicate among collaborating processors. This paper presents an analytical performance model to calculate Message Latency in circuit-switched hypercubic networks in the presence of bursty traffic pattern, which is a typical scenario for multimedia applications. A Message in circuit switching may need a number of connection attempts before successfully setting up a path from source to destination. The proposed model uses the approach of superposing infinite bursty traffic streams to capture the effective traffic entering the network from a source node, which includes the traffic generated by the source and those due to many connection attempts. Results obtained from simulation experiments confirm that the proposed model exhibits a good degree of accuracy for various network sizes and under different operating conditions.