A New Cost-Effective Technique for QoS Support in Clusters

Virtual channels (VCs) are a popular solution for the provision of quality of service (QoS). Current interconnect standards propose 16 or even more VCs for this purpose. However, most implementations do not offer so many VCs because it is too expensive in terms of silicon area. Therefore, a reduction of the number of VCs necessary to support QoS can be very helpful in the switch design and implementation. In this paper, we show that this number of VCs can be reduced if the system is considered as a whole rather than each element being taken separately. The scheduling decisions made at network interfaces can be easily reused at switches without significantly altering the global behavior. In this way, we obtain a noticeable reduction of silicon area, component count and, thus, power consumption, and we can provide similar performance to a more complex architecture. We also show that this is a scalable technique, suitable for the foreseen demands of traffic.