VSE: Virtual Switch Extension for Adaptive CPU Core Assignment in Softirq

An Edge-Overlay model constructing virtual networks using both virtual switches and IP tunnels is promising in cloud datacenter networks. But software-implemented virtual switches can cause performance problems because the packet processing load is concentrated on a particular CPU core. Although multi queue functions like Receive Side Scaling (RSS) can distribute the load onto multiple CPU cores, there are still problems to be solved such as IRQ core collision of heavy traffic flows as well as competitive resource use between physical and virtual for packet processing. In this paper, we propose a software packet processing unit named VSE (Virtual Switch Extension) to address these problems by adaptively determining softirq cores based on both CPU load and VM-running information. Furthermore, the behavior of VSE can be managed by Open Flow controllers. Our performance evaluation results showed that throughput of our approach was higher than an existing RSSbased model as packet processing load increased. In addition, we show that our method prevented performance of high-loaded flows from being degraded by priority-based CPU core selection.