@inproceedings {Simula.simula.866,
	title = {Exploring the Scope of the InfiniBand Congestion Control Mechanism},
	journal = {2012 IEEE International Symposium on Parallel \& Distributed Processing (IPDPS)},
	year = {2012},
	pages = {1131-1143},
	publisher = {IEEE Computer Society},
	type = {Conference},
	abstract = {In a lossless interconnection network, network congestion needs to be detected and resolved to ensure high performance and good utilization of network resources at high network load. If no countermeasure is taken, congestion at a node in the network will stimulate the growth of a congestion tree that not only affects contributors to congestion, but also other traffic flows in the network. Left untouched, the congestion tree will block traffic flows, lead to underutilization of network resources and result in a severe drop in network performance. The InfiniBand standard specifies a congestion control (CC) mechanism to detect and resolve congestion before a congestion tree is able to grow and, by that, hamper the network performance. The InfiniBand CC mechanism includes a rich set of parameters that can be tuned in order to achieve effective CC. Even though it has been shown that the CC mechanism, properly tuned, is able to improve both throughput and fairness in an interconnection network, it has been questioned whether the mechanism is fast enough to keep up with dynamic network traffic, and if a given set of parameter values for a topology is robust when it comes to different traffic patterns, or if the parameters need to be tuned depending on the applications in use. In this paper we address both these questions. Using the three-stage fat-tree topology from the Sun Datacenter InfiniBand Switch 648 as a basis, and a simulator tuned against CC capable InfiniBand hardware, we conduct a systematic study of the efficiency of the InfiniBand CC mechanism as the network traffic becomes increasingly more dynamic. Our studies show that the InfiniBand CC, even when using a single set of parameter values, performs very well as the traffic patterns becomes increasingly more dynamic, outperforming a network without CC in all cases. Our results show throughput increases varying from a few percent, to a seventeen-fold increase.},
	doi = {10.1109/IPDPS.2012.104},
	author = {Ernst Gunnar {Gran} and Reinemo, Sven-Arne and Lysne, Olav and Skeie, Tor and Zahavi, Eitan and Shainer, Gilad},
	editor = {Werner, Bob}
}
@inproceedings {Simula.simula.364,
	title = {On the Relation Between Congestion Control, Switch Arbitration and Fairness},
	journal = {11th IEEE/ACM International Symposium on Cluster, Cloud, and Grid Computing (CCGrid 2011)},
	year = {2011},
	month = {May},
	pages = {342-351},
	publisher = {IEEE},
	type = {Conference},
	abstract = {In lossless interconnection networks such as InfiniBand, congestion control (CC) can be an effective mechanism to achieve high performance and good utilization of network resources. The InfiniBand standard describes CC functionality for detecting and resolving congestion, but the design decisions on how to implement this functionallity is left to the hardware designer. One must be cautious when making these design decisions not to introduce fairness problems, as our study shows. In this paper we study the relationship between congestion control, switch arbitration, and fairness. Specifically, we look at fairness among different traffic flows arriving at a hot spot switch on different input ports, as CC is turned on. In addition we study the fairness among traffic flows at a switch where some flows are exclusive users of their input ports while other flows are sharing an input port (the parking lot problem). Our results show that the implementation of congestion control in a switch is vulnerable to unfairness if care is not taken. In detail, we found that a threshold hysteresis of more than one MTU is needed to resolve arbitration unfairness. Furthermore, to fully solve the parking lot problem, proper configuration of the CC parameters are required.},
	isbn = {978-1-4577-0129-0},
	doi = {10.1109/CCGrid.2011.67},
	author = {Ernst Gunnar {Gran} and Zahavi, Eitan and Reinemo, Sven-Arne and Skeie, Tor and Shainer, Gilad and Lysne, Olav},
	editor = {Buyya, Rajkumar}
}
@inproceedings {Simula.nd.417,
	title = {First Experiences With Congestion Control in InfiniBand Hardware},
	journal = {2010 IEEE International Symposium on Parallel \& Distributed Processing (IPDPS)},
	year = {2010},
	pages = {1-12},
	publisher = {IEEE},
	type = {Conference},
	abstract = {In lossless interconnection networks congestion control (CC) can be an effective mechanism to achieve high performance and good utilization of network resources. Without CC, congestion on one link may grow into a congestion tree that can degrade the performance severely. This degradation can affect not only contributors to the congestion, but also throttles innocent traffic flows in the network. The InfiniBand standard describes CC functionality for detecting and resolving congestion. The InfiniBand CC concept is rich in the way that it specifies a set of parameters that can be tuned in order to achieve effective CC. There is, however, limited experience with the InfiniBand CC mechanism. To the best of our knowledge, only a few simulation studies exist. Recently, InfiniBand CC has been implemented in hardware, and in this paper we present the first experiences with such equipment. We show that the implemented InfiniBand CC mechanism effectively resolves congestion and improves fairness by solving the parking lot problem, if the CC parameters are appropriately set. By conducting extensive testing on a selection of the CC parameters, we have explored the parameter space and found a subset of parameter values that leads to efficient CC for our test scenarios. Furthermore, we show that the InfiniBand CC increases the performance of the well known HPC Challenge benchmark in a congested network.},
	isbn = {978-1-4244-6442-5},
	doi = {10.1109/IPDPS.2010.5470419},
	author = {Ernst Gunnar {Gran} and Eimot, Magne and Reinemo, Sven-Arne and Skeie, Tor and Lysne, Olav and Lars Paul {Huse} and Shainer, Gilad},
	editor = {Phillips, Cynthia}
}
@misc {Simula.netsys.10,
	title = {First Experiences With Congestion Control in InfiniBand Hardware},
	howpublished = {Invited talk at the HPC Advisory Council Switzerland Workshop 2010},
	year = {2010},
	month = {March},
	abstract = {In InfiniBand networks congestion control (CC) can be an effective mechanism to achieve high performance and high utilisation of network resources. Without CC, congestion in one node may severely degrade overall performance. In this talk we introduce the problem of congestion and how it can be avoided with InfiniBand congestion control.},
	author = {Reinemo, Sven-Arne and Ernst Gunnar {Gran} and Eimot, Magne and Skeie, Tor and Lysne, Olav and Lars Paul {Huse} and Shainer, Gilad}
}
