OS4C: An Open-Source SR-IOV System for SmartNIC-based Cloud Platforms

Smart network interface cards (SmartNICs) are programmable network cards that enable the flexible offloading of network- and application-level functionality. The last several years have seen a significant rise in research related to smart, programmable NICs. Meanwhile, several open-source FPGA-based NIC and networking projects have emerged. However, these projects lack many key features necessary for strong performance in cloud settings. We identify Single Root Input/Output Virtualization (SR-IOV) as one of the key missing features in these open-source implementations. SR-IOV enables cloud vendors to grant cloud tenants direct access to hardware resources, dramatically reducing the software overheads of device virtualization. We present OS4C, which extends the popular open-source NIC Corundum [1] with support for SR-IOV. We demonstrate that OS4C can improve virtual machine P99.9 network tail latency by up to 17x, throughput by up to 4x, and CPU effort by up to 3.9x compared to software virtualization. On top of this system, we provide a novel weighted round-robin scheduler that enables tenants and providers to control weight distributions and overhaul the Corundum simulation framework to support multi-tenant tests and performance insights.