Topological Characterization of Hamming and Dragonfly Networks and Its Implications on Routing

Camarero, Cristóbal; Vallejo, Enrique; Beivide, Ramón

doi:10.1145/2677038

Cited by 32 publications

(13 citation statements)

References 36 publications

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“…Such groups are connected on a second-level interconnection pattern. In this work, we focus on dragonfly networks with complete graphs in both hierarchical levels, denoted as canonical dragonflies in [7].…”

Section: Dragonfly Networkmentioning

confidence: 99%

“…Additionally, the global link arrangement specifies the distribution of global links among the routers of each group; in this work we employ the palmtree arrangement [7], but the study and results for other arrangements are similar. An example dragonfly network is depicted in Figure 1 with p = h = 2, a = 4.…”

Section: Dragonfly Networkmentioning

confidence: 99%

“…Several routing mechanisms have been proposed for the dragonfly network [19,18,14,11,7]. In this work we classify them in three categories: oblivious, sourcebased adaptive, and in-transit adaptive routing.…”

Section: Routing Mechanismsmentioning

confidence: 99%

“…With a typical palmtree arrangement of global links [7], these destinations are the h consecutive groups (+1, +2, ..., +h) after the source group. Figure 5 illustrates this traffic pattern with a dragonfly network with h = 3.…”

Section: Adversarial-consecutive Trafficmentioning

confidence: 99%

“…Arranging the global links randomly has been considered before in [7]. However, such mechanism would randomize output nodes for a given subset of the network, but would not guarantee the absence of ADVc or similar traffic patterns.…”

Section: Avoiding the Appearance Of Adversarial-consecutive Trafficmentioning

confidence: 99%

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Network unfairness in dragonfly topologies

et al. 2016

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Dragonfly networks arrange network routers in a two-level hierarchy, providing a competitive cost-performance solution for large systems. Nonminimal adaptive routing (adaptive misrouting) is employed to fully exploit the path diversity and increase the performance under adversarial traffic patterns. Network fairness issues arise in the dragonfly for several combinations of traffic pattern, global misrouting and traffic prioritization policy. Such unfairness prevents a balanced use of the resources across the network nodes and degrades severely the performance of any application running on an affected node. This paper reviews the main causes behind network unfairness in dragonflies, including a new adversarial traffic pattern which can easily occur in actual systems and congests all the global output links of a single router. A solution for the observed unfairness is evaluated using age-based arbitration. Results show that age-based arbitration mitigates fairness issues especially when using in-transit adaptive routing. However, when using source adaptive routing, the saturation of the new traffic pattern interferes with the mechanisms employed to detect remote congestion, and the problem grows with the network size. This makes source adaptive routing in dragonflies based on remote notifications prone to reduced performance, even when using age-based arbitration.

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Section: Dragonfly Networkmentioning

confidence: 99%

Section: Dragonfly Networkmentioning

confidence: 99%

Section: Routing Mechanismsmentioning

confidence: 99%

Section: Adversarial-consecutive Trafficmentioning

confidence: 99%

Section: Avoiding the Appearance Of Adversarial-consecutive Trafficmentioning

confidence: 99%

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Network unfairness in dragonfly topologies

et al. 2016

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Providing differentiated services, congestion management, and deadlock freedom in dragonfly networks with adaptive routing

Yébenes

Escudero-Sahuquillo

García

et al. 2016

Concurrency and Computation

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SummaryThe number of endnodes in high‐performance computing systems has grown significantly in the last years. Hence, the interconnection network has become an essential issue as it may end up being the system bottleneck if it is not properly designed. In that sense, the Dragonfly topology has become very popular for interconnecting high‐performance computing systems in the last years because it offers high performance at an affordable cost. However, when using deterministic minimal‐path routing, this topology is not able to offer a high performance under certain traffic conditions. This problem can be solved by using oblivious or adaptive routing. However, there are no congestion management techniques specially tailored to Dragonfly topologies using oblivious or adaptive routing. Note that in congestion situations, the Dragonfly performance may drop because of the head‐of‐line blocking effect. This effect could be even more dangerous in systems where several applications with different priorities coexist. In this work we propose several techniques especially designed for providing differentiated services and congestion management in Dragonfly networks using oblivious or adaptive routing. First, we propose the hierarchical 3‐level queuing queuing scheme, which configures several virtual channels distributed into 3 virtual networks to reduce the head‐of‐line blocking while deadlocks derived from the routing algorithm are prevented. Second, we extend hierarchical 3‐level queuing to provide differentiated services through 2 different solutions. Finally, some experiments are performed to show the benefits obtained by using the proposed techniques.

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