PicNIC: Predictable Virtualized NIC

Network virtualization stacks such as Andromeda and Virtual Filtering Platform are the linchpins of public clouds hosting Virtual Machines (VMs). The dataplane is based on a combination of high performance OS bypass software and hardware packet processing paths. A key goal is to provide network performance isolation such that workloads of one VM do not adversely impact the network experience of another VM. In this work, we characterize how isolation breakages occur in virtualization stacks and motivate predictable VM performance just as if they were operating on dedicated hardware. We formulate an abstraction of a Predictable Virtualized NIC for bandwidth, latency and packet loss. We propose three constructs to achieve predictability: egress traffic shaping, and a combination of congestion control and CPU-fair weighted fair queueing for ingress isolation. Using these constructs in coherence, we provide the illusion of a dedicated NIC to VMs, all while maintaining the raw performance of the fastpath dataplane.