sEBP: Event Based Polling for Efficient I/O Virtualization

Interrupt virtualization remains a key overhead source in high performance network virtualization (Single-root I/O virtualization or SR-IOV). SR-IOV can give close to line rate network bandwidth and good scalability in the 10 Gbps network environment, however the overhead of the interrupt virtualization in SR-IOV remains non-trivial, due to additional trap-and emulation overhead on the virtual interrupt controller, and high interrupt frequency brought by the high bandwidth network. In this paper we propose sEBP, an event-based polling model to eliminate the interrupts from the critical I/O paths in the virtual environment. A variety of system events are collected by sEBP, either at the guest kernel level or at the VMM level. Upon those events the NIC status is polled. The polling is lightweight, and plenty of system events fulfill the role of the interrupts. By removing the overhead of the interrupts, sEBP manages to achieve up to 59% performance improvement and 23% better scalability ratio.