Virtualization polling engine (vpe): using dedicated cpu cores to accelerate i/o virtualization

Virtual machine (VM) technologies are making rapid progress and VM performance is approaching that of native hardware in many aspects. Achieving high performance for I/O vir-tualization remains a challenge, however, especially for high speed networking devices such as 10 Gigabit Ethernet (10 GbE) NICs. Traditional software-based approaches to I/O virtualization usually suffer significant performance degra-dation compared with native hardware. Hardware-based ap-proaches that allow direct device access in VMs can achieve good performance, albeit at the expense of increased hard-ware cost and increased complexity in achieving tasks such as VM checkpointing, migration, and record/reply. Recently, the trend in microprocessor design has shifted from achieving higher CPU frequencies to putting more cores in a single chip, thus the cost of each core is rapidly decreas-ing. In this paper, we propose a new I/O virtualization approach called the Virtualization Polling Engine (VPE). VPE introduces a concept called virtualization onload, which takes advantage of dedicated CPU cores to help with the vir-tualization of I/O devices by using an event-driven execution model with dedicated polling threads. It can significantly re-duce virtualization overhead and achieve performance close to the hardware-based approaches without requiring special hardware support. Using our VPE approach, we developed a prototype called KVM-VPE to provide Ethernet virtualization support for KVM. Our experiments in a 10GbE testbed showed that VPE significantly outperformed the original KVM. In Net-perf TCP tests our prototype achieved over 5 times the bandwidth for transmitting (Tx) and over 3 times the band-width for receiving (Rx) compared with the original KVM. KVM-VPE also supports direct user application access to the virtual Ethernet interfaces and achieved 7.4 μs end-to-end latency between two VMs on different machines in our testbed. Overall, our research demonstrated that VPE is a promising approach to high performance I/O virtualization in the coming multicore era