Efficient Switches with QoS Support for Clusters∗

Current interconnect standards providing hardware sup-port for quality of service (QoS) consider up to 16 virtual channels (VCs) for this purpose. However, most implemen-tations do not offer so many VCs because they increase the complexity of the switch and the scheduling delays. We have shown that this number of VCs can be significantly reduced, because it is enough to use two VCs for QoS purposes at each switch port. In this paper, we cover the weaknesses of that proposal and, not only we reduce VCs, but we also improve performance due to the flexibility assigning buffer memory.