The Experts below are selected from a list of 6993 Experts worldwide ranked by ideXlab platform

José Duato - One of the best experts on this subject based on the ideXlab platform.

  • A HoL-blocking aware mechanism for selecting the upward path in fat-tree topologies
    The Journal of Supercomputing, 2015
    Co-Authors: C Gomez, M.E. Gomez, F. Gilabert, P. López, José Duato
    Abstract:

    Large cluster-based machines require efficient high-performance interconnection networks. Routing is a key design issue of interconnection networks. Adaptive Routing usually outperforms Deterministic Routing at the expense of introducing out-of-order packet delivery. Many of the commodity interconnects for clusters are based on fat-trees. The adaptive Routing algorithm commonly used in fat-trees is composed of a fully adaptive upward subpath, followed by a Deterministic downward subpath. As the latter is determined by the former, choosing the most adequate upward path for each packet is critical in fat-trees to achieve a good performance. In this paper, we present a mechanism for selecting the upward path in fat-trees, which enables optimum use of the available network resources to achieve a high network throughput. The proposed path selection is destination based, which allows reducing the head-of-line blocking effect. Indeed, the proposed mechanism can be used either as a selection function (the provided path is used as the preferred one), or as a Deterministic Routing algorithm (the path is the only possible one). The results show that the resulting selection function outperforms any other known one. Moreover, the proposed Deterministic Routing algorithm can achieve a similar, or even higher, level of performance than adaptive Routing, while providing in-order packet delivery and a simpler switch implementation.

  • Deterministic Routing with hol blocking awareness for direct topologies
    International Conference on Conceptual Structures, 2013
    Co-Authors: Roberto Penaranda, M.E. Gomez, Pedro López, Crispin Gomez, José Duato
    Abstract:

    Routing is a key design factor to obtain the maximum performance out of interconnection networks. Depending on the number of Routing options that packets may use, Routing algorithms are classified into two categories. If the packet can only use a single predetermined path, Routing is Deterministic, whereas if several paths are available, it is adaptive. It is well-known that adaptive Routing usually outperforms Deterministic Routing. However, adaptive routers are more complex and introduces out-of-order delivery of packets. In this paper, we take up the challenge of developing a Deterministic Routing algorithm for direct topologies that can obtain a similar performance than adaptive Routing, while providing the inherent advantages of Deterministic Routing such as in-order delivery of packets and implementation simplicity. The proposed Deterministic Routing algorithm is aware of the HoL-blocking effect, and it is designed to reduce it, which, as known, it is a key contributor to degrade interconnection network performance.

  • ICCS - Deterministic Routing with HoL-Blocking-Awareness for Direct Topologies
    Procedia Computer Science, 2013
    Co-Authors: Roberto Penaranda, Crispin Gomez, Pedro López, Maria E. Gomez, José Duato
    Abstract:

    Routing is a key design factor to obtain the maximum performance out of interconnection networks. Depending on the number of Routing options that packets may use, Routing algorithms are classified into two categories. If the packet can only use a single predetermined path, Routing is Deterministic, whereas if several paths are available, it is adaptive. It is well-known that adaptive Routing usually outperforms Deterministic Routing. However, adaptive routers are more complex and introduces out-of-order delivery of packets. In this paper, we take up the challenge of developing a Deterministic Routing algorithm for direct topologies that can obtain a similar performance than adaptive Routing, while providing the inherent advantages of Deterministic Routing such as in-order delivery of packets and implementation simplicity. The proposed Deterministic Routing algorithm is aware of the HoL-blocking effect, and it is designed to reduce it, which, as known, it is a key contributor to degrade interconnection network performance.

  • iodet a hol blocking aware Deterministic Routing algorithm for direct topologies
    International Conference on Parallel and Distributed Systems, 2012
    Co-Authors: Roberto Penaranda, M.E. Gomez, Pedro López, Crispin Gomez, José Duato
    Abstract:

    In large parallel computers Routing is a key design point to obtain the maximum possible performance out of the interconnection network. Routing can be classified into two categories depending on the number of Routing options that a packet can use to go from its source to its destination. If the packet can only use a single predetermined path then the Routing is Deterministic, whereas if several paths are possible it is adaptive. It is a well-known fact that adaptive Routing usually outperforms Deterministic Routing; but in this paper we take the challenge of developing a HOL-blocking-aware Deterministic Routing algorithm that can obtain a similar or even better performance than adaptive Routing, while decreasing its implementation complexity and providing some inherent advantages to Deterministic Routing such as in-order delivery of packets. In this large computers regular direct topologies are widely-used, so in this paper we focus on meshes and tori.

  • a survey and evaluation of topology agnostic Deterministic Routing algorithms
    IEEE Transactions on Parallel and Distributed Systems, 2012
    Co-Authors: Jose Flich, José Duato, P. López, Michihiro Koibuchi, Tor Skeie, A Mejia, Olav Lysne, A Robles, Tomas Rokicki, J C Sancho
    Abstract:

    Most standard cluster interconnect technologies are flexible with respect to network topology. This has spawned a substantial amount of research on topology-agnostic Routing algorithms, which make no assumption about the network structure, thus providing the flexibility needed to route on irregular networks. Actually, such an irregularity should be often interpreted as minor modifications of some regular interconnection pattern, such as those induced by faults. In fact, topology-agnostic Routing algorithms are also becoming increasingly useful for networks on chip (NoCs), where faults may make the preferred 2D mesh topology irregular. Existing topology-agnostic Routing algorithms were developed for varying purposes, giving them different and not always comparable properties. Details are scattered among many papers, each with distinct conditions, making comparison difficult. This paper presents a comprehensive overview of the known topology-agnostic Routing algorithms. We classify these algorithms by their most important properties, and evaluate them consistently. This provides significant insight into the algorithms and their appropriateness for different on- and off-chip environments.

M.E. Gomez - One of the best experts on this subject based on the ideXlab platform.

  • A HoL-blocking aware mechanism for selecting the upward path in fat-tree topologies
    The Journal of Supercomputing, 2015
    Co-Authors: C Gomez, M.E. Gomez, F. Gilabert, P. López, José Duato
    Abstract:

    Large cluster-based machines require efficient high-performance interconnection networks. Routing is a key design issue of interconnection networks. Adaptive Routing usually outperforms Deterministic Routing at the expense of introducing out-of-order packet delivery. Many of the commodity interconnects for clusters are based on fat-trees. The adaptive Routing algorithm commonly used in fat-trees is composed of a fully adaptive upward subpath, followed by a Deterministic downward subpath. As the latter is determined by the former, choosing the most adequate upward path for each packet is critical in fat-trees to achieve a good performance. In this paper, we present a mechanism for selecting the upward path in fat-trees, which enables optimum use of the available network resources to achieve a high network throughput. The proposed path selection is destination based, which allows reducing the head-of-line blocking effect. Indeed, the proposed mechanism can be used either as a selection function (the provided path is used as the preferred one), or as a Deterministic Routing algorithm (the path is the only possible one). The results show that the resulting selection function outperforms any other known one. Moreover, the proposed Deterministic Routing algorithm can achieve a similar, or even higher, level of performance than adaptive Routing, while providing in-order packet delivery and a simpler switch implementation.

  • Deterministic Routing with hol blocking awareness for direct topologies
    International Conference on Conceptual Structures, 2013
    Co-Authors: Roberto Penaranda, M.E. Gomez, Pedro López, Crispin Gomez, José Duato
    Abstract:

    Routing is a key design factor to obtain the maximum performance out of interconnection networks. Depending on the number of Routing options that packets may use, Routing algorithms are classified into two categories. If the packet can only use a single predetermined path, Routing is Deterministic, whereas if several paths are available, it is adaptive. It is well-known that adaptive Routing usually outperforms Deterministic Routing. However, adaptive routers are more complex and introduces out-of-order delivery of packets. In this paper, we take up the challenge of developing a Deterministic Routing algorithm for direct topologies that can obtain a similar performance than adaptive Routing, while providing the inherent advantages of Deterministic Routing such as in-order delivery of packets and implementation simplicity. The proposed Deterministic Routing algorithm is aware of the HoL-blocking effect, and it is designed to reduce it, which, as known, it is a key contributor to degrade interconnection network performance.

  • iodet a hol blocking aware Deterministic Routing algorithm for direct topologies
    International Conference on Parallel and Distributed Systems, 2012
    Co-Authors: Roberto Penaranda, M.E. Gomez, Pedro López, Crispin Gomez, José Duato
    Abstract:

    In large parallel computers Routing is a key design point to obtain the maximum possible performance out of the interconnection network. Routing can be classified into two categories depending on the number of Routing options that a packet can use to go from its source to its destination. If the packet can only use a single predetermined path then the Routing is Deterministic, whereas if several paths are possible it is adaptive. It is a well-known fact that adaptive Routing usually outperforms Deterministic Routing; but in this paper we take the challenge of developing a HOL-blocking-aware Deterministic Routing algorithm that can obtain a similar or even better performance than adaptive Routing, while decreasing its implementation complexity and providing some inherent advantages to Deterministic Routing such as in-order delivery of packets. In this large computers regular direct topologies are widely-used, so in this paper we focus on meshes and tori.

  • Beyond Fat--tree: Unidirectional Load--Balanced Multistage Interconnection Network
    Computer Architecture Letters, 2008
    Co-Authors: C Gomez, M.E. Gomez, F. Gilabert, P. López, José Duato
    Abstract:

    The fat-tree is one of the most widely-used topologies by interconnection network manufacturers. Recently, it has been demonstrated that a Deterministic Routing algorithm that optimally balances the network traffic can not only achieve almost the same performance than an adaptive Routing algorithm but also outperforms it. On the other hand, fat-trees require a high number of switches with a non-negligible wiring complexity. In this paper, we propose replacing the fat-tree by a unidirectional multistage interconnection network (UMIN) that uses a traffic balancing Deterministic Routing algorithm. As a consequence, switch hardware is almost reduced to the half, decreasing, in this way, the power consumption, the arbitration complexity, the switch size itself, and the network cost. Preliminary evaluation results show that the UMIN with the load balancing scheme obtains lower latency than fat-tree for low and medium traffic loads. Furthermore, in networks with a high number of stages or with high radix switches, it obtains the same, or even higher, throughput than fat-tree.

  • RUFT: Simplifying the Fat-Tree Topology
    Parallel and Distributed Systems, 2008. ICPADS '08. 14th IEEE International Conference on, 2008
    Co-Authors: C Gomez, M.E. Gomez, F. Gilabert, P. López, José Duato
    Abstract:

    The fat-tree is one of the most widely-used topologies by interconnection network manufacturers. Recently, a Deterministic Routing algorithm that optimally balances the network traffic in fat--trees was proposed. It can not only achieve almost the same performance than adaptive Routing, but also outperforms it for some traffic patterns. Nevertheless, fat-trees require a high number of switches with a non-negligible wiring complexity. In this paper, we propose replacing the fat-tree by an unidirectional multistage interconnection network referred to as reduced unidirectional fat-tree (RUFT) that uses a a simplified version of the aforementioned Deterministic Routing algorithm. As a consequence, switch hardware is almost reduced to the half, decreasing, in this way, power consumption, arbitration complexity, switch size, and network cost. Evaluation results show that RUFT obtains lower latency than fat-tree for low and medium traffic loads. Furthermore, in large networks, it obtains almost the same throughput than the classical fat-tree.

Mohamed Ould-khaoua - One of the best experts on this subject based on the ideXlab platform.

  • A queueing model for predicting message latency in uni-directional k-ary n-cubes with Deterministic Routing and non-uniform traffic
    Cluster Computing, 2007
    Co-Authors: S. Loucif, Mohamed Ould-khaoua, Geyong Min
    Abstract:

    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.

  • Stochastic Analysis of Deterministic Routing Algorithms in the Presence of Self-Similar Traffic
    The Journal of Supercomputing, 2006
    Co-Authors: Geyong Min, Mohamed Ould-khaoua, Demetres D. Kouvatsos, Irfan U. Awan
    Abstract:

    Many performance models for Deterministic Routing in multicomputer interconnection networks have been derived and analyzed under the assumption of the traditional Poisson stochastic arrival process, which is inherently unable to capture traffic self-similarity revealed by many real-world parallel applications. In an effort towards understanding the network performance under various traffic loads and different design alternatives, this paper presents an analytical model for dimension-ordered Routing in k -ary n -cubes when subjected to self-similar traffic. As the service time, blocking probability and waiting time experienced by a message vary from a dimension to another, the design of such a model for dimension-ordered Routing poses greater challenges. The developed analytical model is then used to investigate the efficiency of two different ways to organize virtual channels for Deterministic Routing and to evaluate the impact of self-similar traffic with various Hurst parameters on network performance.

  • PERFORMANCE ANALYSIS OF Deterministic Routing IN WORMHOLE k-ARY n-CUBES WITH VIRTUAL CHANNELS
    Journal of Interconnection Networks, 2002
    Co-Authors: Hamid Sarbazi-azad, Ahmad Khonsari, Mohamed Ould-khaoua
    Abstract:

    Adding virtual channels to wormhole-routed networks greatly improves performance because they reduce blocking by acting as "bypass" lanes for non-blocked messages. Although several analytical models have been proposed in the literature for k-ary n-cubes with Deterministic Routing, most of them have not included the effects of virtual channel multiplexing on network performance. This paper proposes a new and simple analytical model to compute message latency in k-ary n-cubes with an arbitrary number of virtual channels. Results from simulation experiments confirm that the proposed model exhibits a good degree of accuracy for various network sizes and under different operating conditions. The proposed model is then used to investigate the relative performance merits of two different organisations of virtual channels.

  • On the merits of hypermeshes and tori with adaptive Routing
    Journal of Systems Architecture, 2002
    Co-Authors: S. Loucif, Mohamed Ould-khaoua
    Abstract:

    Most existing multicomputers employ the torus topology along with Deterministic Routing to ensure simple router implementation, and thus fast communication. Efficient adaptive Routing algorithms with minimum implementation requirements have recently been proposed to overcome the limitations of Deterministic Routing. Such algorithms have been incorporated in the latest generation of multicomputers, e.g. the Cray T3E, which are still based on low-dimensional k-ary n-cubes. Our previous studies have shown that a hypergraph network, referred to as the distributed crossbar switch hypermesh (DCSH), has several topological and performance advantages over traditional k-ary n-cubes when Deterministic Routing is used. This paper evaluates the relative merits of the DCSH and a variant of k-ary n-cubes, the torus, in the context of adaptive Routing. The evaluation takes into account the effects of increased switching delays due to adaptivity, and implementation costs for various technologies (e.g. VLSI and multiple-chip technology). The results reveal that the DCSH is a potential alternative as a future high-performance multicomputer network, which can fully exploit the benefits of adaptive wormhole Routing. Even though the torus has higher bandwidth channels than its DCSH counterpart, due to its simpler interconnect structure, adaptivity cannot reduce its higher message blocking delays inherent in its topology.

  • The impact of virtual channel allocation on the performance of Deterministic wormhole-routed k-ary n-cubes
    Simulation Modelling Practice and Theory, 2002
    Co-Authors: S. Loucif, Mohamed Ould-khaoua
    Abstract:

    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.

Crispin Gomez - One of the best experts on this subject based on the ideXlab platform.

  • PDP - XORAdap: A HoL-Blocking Aware Adaptive Routing Algorithm
    2015 23rd Euromicro International Conference on Parallel Distributed and Network-Based Processing, 2015
    Co-Authors: Roberto Penaranda, Crispin Gomez, Maria E. Gomez, Pedro López
    Abstract:

    Routing is a key parameter in the design of the interconnection network of large parallel computers. Depending on the number of Routing options available for each packet, Routing algorithms can be Deterministic (one available path) or adaptive (several ones). Adaptive Routing usually outperforms Deterministic Routing but it also may increase the Head-of-Line blocking effect. Usually, adaptive Routing uses virtual channels to provide Routing flexibility and to guarantee deadlock freedom. On the other hand, Deterministic Routing is simpler and therefore it has lower Routing delay. In this paper, we take the challenge of developing new Routing algorithms for direct topologies that exploit virtual channels in an efficient way combining the good properties of both Routing algorithms types: flexibility and reduced HoL blocking. To do that, this paper proposes several hybrid (combination of adaptivity and determinism) simple mechanisms to perform an efficient distribution of packets among virtual channels based on their destination. The resulting Routing mechanisms are able to adapt to the different traffic patterns to obtain the best performance while keeping the simplicity of Routing.

  • Deterministic Routing with hol blocking awareness for direct topologies
    International Conference on Conceptual Structures, 2013
    Co-Authors: Roberto Penaranda, M.E. Gomez, Pedro López, Crispin Gomez, José Duato
    Abstract:

    Routing is a key design factor to obtain the maximum performance out of interconnection networks. Depending on the number of Routing options that packets may use, Routing algorithms are classified into two categories. If the packet can only use a single predetermined path, Routing is Deterministic, whereas if several paths are available, it is adaptive. It is well-known that adaptive Routing usually outperforms Deterministic Routing. However, adaptive routers are more complex and introduces out-of-order delivery of packets. In this paper, we take up the challenge of developing a Deterministic Routing algorithm for direct topologies that can obtain a similar performance than adaptive Routing, while providing the inherent advantages of Deterministic Routing such as in-order delivery of packets and implementation simplicity. The proposed Deterministic Routing algorithm is aware of the HoL-blocking effect, and it is designed to reduce it, which, as known, it is a key contributor to degrade interconnection network performance.

  • ICCS - Deterministic Routing with HoL-Blocking-Awareness for Direct Topologies
    Procedia Computer Science, 2013
    Co-Authors: Roberto Penaranda, Crispin Gomez, Pedro López, Maria E. Gomez, José Duato
    Abstract:

    Routing is a key design factor to obtain the maximum performance out of interconnection networks. Depending on the number of Routing options that packets may use, Routing algorithms are classified into two categories. If the packet can only use a single predetermined path, Routing is Deterministic, whereas if several paths are available, it is adaptive. It is well-known that adaptive Routing usually outperforms Deterministic Routing. However, adaptive routers are more complex and introduces out-of-order delivery of packets. In this paper, we take up the challenge of developing a Deterministic Routing algorithm for direct topologies that can obtain a similar performance than adaptive Routing, while providing the inherent advantages of Deterministic Routing such as in-order delivery of packets and implementation simplicity. The proposed Deterministic Routing algorithm is aware of the HoL-blocking effect, and it is designed to reduce it, which, as known, it is a key contributor to degrade interconnection network performance.

  • iodet a hol blocking aware Deterministic Routing algorithm for direct topologies
    International Conference on Parallel and Distributed Systems, 2012
    Co-Authors: Roberto Penaranda, M.E. Gomez, Pedro López, Crispin Gomez, José Duato
    Abstract:

    In large parallel computers Routing is a key design point to obtain the maximum possible performance out of the interconnection network. Routing can be classified into two categories depending on the number of Routing options that a packet can use to go from its source to its destination. If the packet can only use a single predetermined path then the Routing is Deterministic, whereas if several paths are possible it is adaptive. It is a well-known fact that adaptive Routing usually outperforms Deterministic Routing; but in this paper we take the challenge of developing a HOL-blocking-aware Deterministic Routing algorithm that can obtain a similar or even better performance than adaptive Routing, while decreasing its implementation complexity and providing some inherent advantages to Deterministic Routing such as in-order delivery of packets. In this large computers regular direct topologies are widely-used, so in this paper we focus on meshes and tori.

  • ICPADS - IODET: A HoL-blocking-aware Deterministic Routing Algorithm for Direct Topologies
    2012 IEEE 18th International Conference on Parallel and Distributed Systems, 2012
    Co-Authors: Roberto Penaranda, Crispin Gomez, Pedro López, Maria E. Gomez, José Duato
    Abstract:

    In large parallel computers Routing is a key design point to obtain the maximum possible performance out of the interconnection network. Routing can be classified into two categories depending on the number of Routing options that a packet can use to go from its source to its destination. If the packet can only use a single predetermined path then the Routing is Deterministic, whereas if several paths are possible it is adaptive. It is a well-known fact that adaptive Routing usually outperforms Deterministic Routing; but in this paper we take the challenge of developing a HOL-blocking-aware Deterministic Routing algorithm that can obtain a similar or even better performance than adaptive Routing, while decreasing its implementation complexity and providing some inherent advantages to Deterministic Routing such as in-order delivery of packets. In this large computers regular direct topologies are widely-used, so in this paper we focus on meshes and tori.

F. Gilabert - One of the best experts on this subject based on the ideXlab platform.

  • A HoL-blocking aware mechanism for selecting the upward path in fat-tree topologies
    The Journal of Supercomputing, 2015
    Co-Authors: C Gomez, M.E. Gomez, F. Gilabert, P. López, José Duato
    Abstract:

    Large cluster-based machines require efficient high-performance interconnection networks. Routing is a key design issue of interconnection networks. Adaptive Routing usually outperforms Deterministic Routing at the expense of introducing out-of-order packet delivery. Many of the commodity interconnects for clusters are based on fat-trees. The adaptive Routing algorithm commonly used in fat-trees is composed of a fully adaptive upward subpath, followed by a Deterministic downward subpath. As the latter is determined by the former, choosing the most adequate upward path for each packet is critical in fat-trees to achieve a good performance. In this paper, we present a mechanism for selecting the upward path in fat-trees, which enables optimum use of the available network resources to achieve a high network throughput. The proposed path selection is destination based, which allows reducing the head-of-line blocking effect. Indeed, the proposed mechanism can be used either as a selection function (the provided path is used as the preferred one), or as a Deterministic Routing algorithm (the path is the only possible one). The results show that the resulting selection function outperforms any other known one. Moreover, the proposed Deterministic Routing algorithm can achieve a similar, or even higher, level of performance than adaptive Routing, while providing in-order packet delivery and a simpler switch implementation.

  • Beyond Fat--tree: Unidirectional Load--Balanced Multistage Interconnection Network
    Computer Architecture Letters, 2008
    Co-Authors: C Gomez, M.E. Gomez, F. Gilabert, P. López, José Duato
    Abstract:

    The fat-tree is one of the most widely-used topologies by interconnection network manufacturers. Recently, it has been demonstrated that a Deterministic Routing algorithm that optimally balances the network traffic can not only achieve almost the same performance than an adaptive Routing algorithm but also outperforms it. On the other hand, fat-trees require a high number of switches with a non-negligible wiring complexity. In this paper, we propose replacing the fat-tree by a unidirectional multistage interconnection network (UMIN) that uses a traffic balancing Deterministic Routing algorithm. As a consequence, switch hardware is almost reduced to the half, decreasing, in this way, the power consumption, the arbitration complexity, the switch size itself, and the network cost. Preliminary evaluation results show that the UMIN with the load balancing scheme obtains lower latency than fat-tree for low and medium traffic loads. Furthermore, in networks with a high number of stages or with high radix switches, it obtains the same, or even higher, throughput than fat-tree.

  • RUFT: Simplifying the Fat-Tree Topology
    Parallel and Distributed Systems, 2008. ICPADS '08. 14th IEEE International Conference on, 2008
    Co-Authors: C Gomez, M.E. Gomez, F. Gilabert, P. López, José Duato
    Abstract:

    The fat-tree is one of the most widely-used topologies by interconnection network manufacturers. Recently, a Deterministic Routing algorithm that optimally balances the network traffic in fat--trees was proposed. It can not only achieve almost the same performance than adaptive Routing, but also outperforms it for some traffic patterns. Nevertheless, fat-trees require a high number of switches with a non-negligible wiring complexity. In this paper, we propose replacing the fat-tree by an unidirectional multistage interconnection network referred to as reduced unidirectional fat-tree (RUFT) that uses a a simplified version of the aforementioned Deterministic Routing algorithm. As a consequence, switch hardware is almost reduced to the half, decreasing, in this way, power consumption, arbitration complexity, switch size, and network cost. Evaluation results show that RUFT obtains lower latency than fat-tree for low and medium traffic loads. Furthermore, in large networks, it obtains almost the same throughput than the classical fat-tree.

  • ICPADS - RUFT: Simplifying the Fat-Tree Topology
    2008 14th IEEE International Conference on Parallel and Distributed Systems, 2008
    Co-Authors: Crispin Gomez, F. Gilabert, Pedro López, Maria E. Gomez, José Duato
    Abstract:

    The fat-tree is one of the most widely-used topologies by interconnection network manufacturers. Recently, a Deterministic Routing algorithm that optimally balances the network traffic in fat--trees was proposed. It can not only achieve almost the same performance than adaptive Routing, but also outperforms it for some traffic patterns. Nevertheless, fat-trees require a high number of switches with a non-negligible wiring complexity. In this paper, we propose replacing the fat-tree by an unidirectional multistage interconnection network referred to as reduced unidirectional fat-tree (RUFT) that uses a a simplified version of the aforementioned Deterministic Routing algorithm. As a consequence, switch hardware is almost reduced to the half, decreasing, in this way, power consumption, arbitration complexity, switch size, and network cost. Evaluation results show that RUFT obtains lower latency than fat-tree for low and medium traffic loads. Furthermore, in large networks, it obtains almost the same throughput than the classical fat-tree.

  • Deterministic versus adaptive Routing in fat trees
    International Parallel and Distributed Processing Symposium, 2007
    Co-Authors: Crispin Gomez, M.E. Gomez, F. Gilabert, Pedro López, José Duato
    Abstract:

    Clusters of PCs have become very popular to build high performance computers. These machines use commodity PCs linked by a high speed interconnect. Routing is one of the most important design issues of interconnection networks. Adaptive Routing usually better balances network traffic, thus allowing the network to obtain a higher throughput. However, adaptive Routing introduces out-of-order packet delivery, which is unacceptable for some applications. Concerning topology, most of the commercially available interconnects are based on fat-tree. Fat-trees offer a rich connectivity among nodes, making possible to obtain paths between all source-destination pairs that do not share any link. We exploit this idea to propose a Deterministic Routing algorithm for fat-trees, comparing it with adaptive Routing in several workloads. The results show that Deterministic Routing can achieve a similar, and in some scenarios higher, level of performance than adaptive Routing, while providing in-order packet delivery.