2006 USENIX Annual Technical Conference Abstract
Pp. 2942 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.
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