Red Hat Bugzilla – Bug 473114
RHEL 5.3: allow virtio_net support larger MTU sizes
Last modified: 2009-01-20 14:58:56 EST
Currently, the virtio_net driver doesn't support setting it's MTU size to more than 1500 bytes: $> ip link set eth0 mtu 9000 SIOCSIFMTU: Invalid argument In order to gain the performance improvement resulting from less packet overhead, it's quite common for customers to configure their network so that the entire path between two nodes support jumbo frames (i.e. frame size of 9000 bytes). Since virtio_net doesn't support this, it's impossible to obtain this benefit with KVM/virtio guests. The patch to implement this support is quite trivial and has been just submitted upstream here: http://kerneltrap.org/mailarchive/linux-netdev/2008/11/26/4239974
Created attachment 324771 [details] virtio_net-jumbo-frame-support.patch
in kernel-2.6.18-126.el5 You can download this test kernel from http://people.redhat.com/dzickus/el5
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2009-0225.html