ES2: Aiming at an Optimal Virtual I/O Event Path
Xiaokang Hu, Wang Zhang, Jian Li, Ruhui Ma, Feng Wu, Haibing Guan · 2017
Improving the performance of I/O virtualization is a key issue for cloud and datacenter infrastructures, especially with the rapid increase of network interconnection speeds. Previous efforts have made the performance overhead associated with the virtual I/O data path largely negligible. The remaining bottlenecks mainly lie in the event path: hypervisor interventions trigger costly virtual machine (VM) exits and lead to dramatical performance degradation. Aiming at an optimal virtual I/O event path, we propose ES2, a comprehensive scheme that simultaneously improves bidirectional I/O event delivery between guest VMs and their devices. ES2 can provide efficient I/O request delivery, non-exit interrupt delivery and enhanced I/O responsiveness. Moreover, it does not require any modification to guest operating system (OS) or compromise any virtualization benefit. We demonstrate that ES2 greatly reduces VM exit rate with the time in guest (TIG) for I/O processing above 96% for TCP streams and 99% for UDP streams, increases guest throughput by 1.8× for Memcached and 2× for Apache, and keeps guest latency at a very low level.