QoS provision in hierarchical and non-hierarchical switch architectures

Abstract

Quality of service (QoS) provision has become an important aspect of high-performance computing interconnection networks. Proof of that is the inclusion of mechanisms targeted to the provision of QoS by the main interconnection technologies such as Gigabit Ethernet, Infiniband (IB) and Omni-Path (OPA). A key component of QoS provision is the output scheduling algorithm, which determines when a packet should be transmitted. An ideal scheduling algorithm should satisfy two main properties: good end-to-end latency and implementation simplicity. Table-based schedulers are able to provide these two properties, and because of this, IB and OPA have implemented this approach. In this paper, we present a comparative study in terms of QoS provision between these two dominating interconnection technologies. Those interconnection technologies are also two examples of non-hierarchical and hierarchical switch architectures, respectively, which gives the results of this study greater significance. In order to carry out the study, the Deficit Table scheduler (DTable) has been used. DTable is a table-based scheduling algorithm which offers a good balance between end-to-end latency and implementation cost.