[2015] Vhost: Sharing is better by Eyal Moscovici and Bandan Das

vhost provides virtio emulation in the kernel and avoids expensive system calls. This talk focuses on various mechanisms that have been proposed to improve vhost scalability and performance. The current stable design uses a dedicated kernel worker thread for every vhost device. There are alternative proposals such as a vhost thread running on each CPU core in lieu of creating a per-device thread, using Concurrency managed system workqueues to handle work, and polling virt queues instead of relying on notifications. We start with an introduction to vhost, descriptions and potential complications with several proposed RFCs and some performance comparisons. We hope that this discussion will help us converge to a stable next generation vhost architecture. Although the design implications are applicable to NET and SCSI virtual devices, we would be primarily focusing on Network performance.

Bandan Das
Software Engineer, Red Hat
Bandan Das is a Software Engineer in the Virtualization group at Red Hat. He likes working on the Linux kernel, he usually picks up work that everyone else has forgotten about or don't want to work on.

Eyal Moscovici
Eyal is a research student at IBM Haifa Research Lab, Israel. He is currently working towards a M.Sc. degree in computer science at the Technion, Israel Institute of Technology under the advisement of Prof. Dan Tsafrir. He is researching I/O virtualization optimization to improve server performance in cloud data centers. He has been working on enhancements for vhost since 2013 as part of his research, focusing on improving the performance of paravirtual I/O in the Linux kernel.