Fair multithreading on packet processors for scalable network virtualization

Network virtualization requires careful control of networking resources, including link bandwidth, router memory, and packet processing time. Isolation and fair sharing of processing resources in current high-performance packet processors occur at the granularity of entire processor cores. Scaling of network virtualization to larger numbers of parallel slices requires a more fine-grained processor sharing mechanism. Our work presents a novel approach, called Fair Multithreading (FMT), that allows hardware threads to share a processor core while ensuring isolation and weighted fair access. We present an analysis of the FMT algorithm and a prototype implementation on a NetFPGA system. Our evaluation results indicate that FMT can be implemented at speeds that are necessary to make scheduling decisions at the instruction level. We show the impact of having such fine-grained processor schedulers in substrate nodes by comparing the resource utilization of virtual network slices in our system to traditional whole-core allocations. Our simulation results show the FMT-based substrate networks can be utilized more efficiently and more virtual network requests can be accommodated. These results indicate the significant improvement in system scalability that can be gained from our fine-grained processor scheduling system.