BBQ: A straightforward queuing scheme to reduce HoL-blocking in high-performance hybrid networks

Abstract

Head-of-Line (HoL) blocking is a well-known phenomenon that may dramatically degrade the performance of the modern high-performance interconnection networks. Many techniques have been proposed to solve this problem, most of them based on separating traffic flows into different queues at switch ports. However, the efficiency of these proposals may vary depending on the network topology or routing algorithm, as many of them are not aware of any specific network configuration. By contrast, other schemes are tailored to specific topologies like fat-trees, achieving a greater efficiency than "topology-agnostic" schemes. In this paper we propose a straightforward queuing scheme intended to be used in an efficient, recently-proposed hybrid topology. Our proposal significantly boosts network performance with respect to other queuing schemes while requiring similar or fewer resources. Moreover, the implementation of this scheme in InfiniBand-based networks is elementary thanks to the mapping of Service-Levels to Virtual-Lanes supported by this specification. © 2013 Springer-Verlag.