ERTOS Public Seminar
Improving the performance of network virtualization
Willy Zwaenepoel, EPFL, Switzerland
Time/Venue
28th November 2006, 11 pm
National ICT Australia Ltd, Level 1 Seminar Room, 223 Anzac Parade (Building L5), Kensington NSW 2052
Abstract
Despite recent advances in virtual machine technology, virtualization overhead seriously degrades the performance of network-intensive applications. In this talk I will analyze the sources of this overhead, and I will present two approaches to address the problem, a software-only approach and a hardware-software approach. The software-only approach defines a new high-level virtual network interface, which allows virtualized operating systems to take advantage of common optimizations found in hardware network interfaces, such as scatter-gather DMA, checksum offloading, and TCP segmentation offloading. This approach provides transmit performance far superior to the common approach of using the lowest-denominator virtual network interface definition, but it does not do much for receive performance. The hardware-software approach uses a new hardware network interface card, which supports multiple concurrent "contexts" on the device, each of which can be used in isolation by a separate virtual machine. Protection between contexts and virtual machines is guaranteed by the hardware and a modified version of the hypervisor. This approach improves both transmit and receive performance, and scales to a large number of virtual machines. This is joint work with Alan Cox, Scott Rixner, Jeff Shafer and Paul Willman from Rice University, and Aravind Menon from EPFL.