Virtual-channel flow control

Network throughput can be increased by dividing the buffer storage associated with each network channel into several virtual channels. Each physical channel is associated with several small queues, virtual channels, rather than a single deep queue. The virtual channels associated with one physical channel are allocated independently but compete with each other for physical bandwidth. Virtual channels decouple buffer resources from transmission resources. This decoupling allows active messages to pass blocked messages using network bandwidth that would otherwise be left idle. The paper studies the performance of networks using virtual channels using both analysis and simulation. These studies show that virtual channels increase network throughput, by a factor of four for 10-stage networks, and reduce the dependence of throughput on the depth of the network.>