Bug 473114 - RHEL 5.3: allow virtio_net support larger MTU sizes
Summary: RHEL 5.3: allow virtio_net support larger MTU sizes
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel
Version: 5.3
Hardware: All
OS: Linux
high
high
Target Milestone: rc
: ---
Assignee: Mark McLoughlin
QA Contact: Martin Jenner
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2008-11-26 15:55 UTC by Mark McLoughlin
Modified: 2009-01-20 19:58 UTC (History)
6 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2009-01-20 19:58:56 UTC
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)
virtio_net-jumbo-frame-support.patch (1.64 KB, patch)
2008-11-26 17:46 UTC, Mark McLoughlin
no flags Details | Diff


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2009:0225 0 normal SHIPPED_LIVE Important: Red Hat Enterprise Linux 5.3 kernel security and bug fix update 2009-01-20 16:06:24 UTC

Description Mark McLoughlin 2008-11-26 15:55:00 UTC
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

Comment 2 Mark McLoughlin 2008-11-26 17:46:23 UTC
Created attachment 324771 [details]
virtio_net-jumbo-frame-support.patch

Comment 5 Don Zickus 2008-12-09 21:05:39 UTC
in kernel-2.6.18-126.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Comment 8 errata-xmlrpc 2009-01-20 19:58:56 UTC
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


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