Incorporating Quality-of-Service in the Virtual Interface Architecture

User-level Networking (ULN) is gaining rapid accep-tance in the commercial world with Virtual Interface Archi-tecture (VIA), and Infiniband more recently, being touted as the interface of choice to diverse peripherals. There is an important issue with respect to ULNs that has been largely unaddressed. This is the issue of accommodating multiple communication channels (scalability) and being able to sus-tain the Quality-of-Service (QoS) requirements of each of these channels. Removing the operating system from the critical path makes the scalability and QoS issue all that much harder since the supervisory role to prevent interfer-ence across channels has to be performed by the network in-terface. This paper argues for a different approach to struc-turing the processing of operations (called PVIA) on the network interface than what is widely used. This newer ap-proach makes it easier to incorporate QoS features, which is referred to as QoSVIA. All these mechanisms have been implemented on an actual Myrinet cluster. The results from the implementation, together with detailed simulations, il-lustrate the potential of QoSVIA being able to accommo-date the QoS needs of a larger number of channels than the mechanisms in use today. 1