Check out the new USENIX Web site.

USENIX, The Advanced Computing Systems Association

2006 USENIX Annual Technical Conference Abstract

Pp. 29–42 of the Proceedings

High Performance VMM-Bypass I/O in Virtual Machines

Jiuxing Liu, IBM T.J. Watson Research Center; Wei Huang, The Ohio State University; Bulent Abali, IBM T.J. Watson Research Center; Dhabaleswar K. Panda, The Ohio State University


Currently, I/O device virtualization models in virtual machine (VM) environments require involvement of a virtual machine monitor (VMM) and/or a privileged VM for each I/O operation, which may turn out to be a performance bottleneck for systems with high I/O demands, especially those equipped with modern high speed interconnects such as InfiniBand.

In this paper, we propose a new device virtualization model called VMM-bypass I/O, which extends the idea of OS-bypass originated from user-level communication. Essentially, VMM-bypass allows time-critical I/O operations to be carried out directly in guest VMs without involvement of the VMM and/or a privileged VM. By exploiting the intelligence found in modern high speed network interfaces, VMM-bypass can significantly improve I/O and communication performance for VMs without sacrificing safety or isolation.

To demonstrate the idea of VMM-bypass, we have developed a prototype called Xen-IB, which offers InfiniBand virtualization support in the Xen 3.0 VM environment. Xen-IB runs with current InfiniBand hardware and does not require modifications to existing user-level applications or kernel-level drivers that use InfiniBand. Our performance measurements show that Xen-IB is able to achieve nearly the same raw performance as the original InfiniBand driver running in a non-virtualized environment.

  • View the full text of this paper in HTML and PDF. Listen to the presentation in MP3 format.
    Click here if you have forgotten your password Until June 2007, you will need your USENIX membership identification in order to access the full papers. The Proceedings are published as a collective work, © 2006 by the USENIX Association. All Rights Reserved. Rights to individual papers remain with the author or the author's employer. Permission is granted for the noncommercial reproduction of the complete work for educational or research purposes. USENIX acknowledges all trademarks within this paper.

  • If you need the latest Adobe Acrobat Reader, you can download it from Adobe's site.
To become a USENIX Member, please see our Membership Information.

Last changed: 15 Sept. 2006 ch