Providing quality of service in omni-path networks

Abstract

New hierarchical crossbar switch architectures, such as Omni-Path (OPA) and Cray X2, have appeared to improve packet latency, reduce overall cost and increase fault tolerance of the high-performance interconnection networks in supercomputing and data center systems. These and other interconnect technologies (Infiniband or 40/100 Gigabit Ethernet) include support to provide quality of service (QoS) to the applications. In this paper, we show how this QoS support can be enabled to achieve bandwidth and/or latency differentiation in Omni-Path interconnection networks, as a representative case of hierarchical switches. To do that, three different table-based schedulers are used. We include the description of these schedulers and a comparative study by using the results obtained when we evaluate them with Hiperion, a simulation tool that implements an OPA model.

Development of a mathematical model for assessing the quality of service on a packet switching subnet

“…As a specific objective function, let's consider the average delay in a single-instrument queuing system (7). The quality of service function of the circuit switching network is defined as a function of explicit load losses in the IGP j (9). The probability of occupancy of channels in IGP j was determined by the Erlang formula (10).…”

“…In the article [9], the authors show that it is possible to ensure the quality of the network by differentiating the bandwidth with a multipath connection, for its implementation using new architectures of hierarchical crossbar switches that provide quality of service (QoS) applications. Also in the work, based on the results obtained, a comparative study of three schedulers was carried out using the Hiperion modeling tool.…”

“…The work considers various aspects related to the provision of quality of service. Nevertheless, papers [9][10][11][12] do not address the specific problems of packet switching subnetworks.…”