xen_netfront: xennet: skb rides the rocket


#1

I just built a new VM using VyOS 1.1.0 to replace my existing VC6.6 VM. This is operating on a Xenserver 6.2 machine as a transparent firewall between external and internal virtual NICS (all other VMs are only connected to the internal virtual NIC).

As soon as I swapped out the old Vyatta VM for the new VyOS one and then booted VyOS I start getting notifications in the console every 15-30 seconds of the following:

(where XX is usually 19 or 20)

In my searching, I’m finding some ominous references to these messages being tied to packet loss due to a bug introduced in Linux kernels starting with 3.7 (and apparently not still fixed as far as I can tell).

This is a MAJOR issue considering that the whole point of VyOS is a firewall. If there are packet loss issues with Xen VMs that pretty much makes it useless in that configuration.

I’ve been able to stop those messages from appearing by turning off scatter-gather on eth0 (ethtool -K eth0 sg off) based on some of the threads I found, but I have no idea how this will ultimately affect the performance or stability of the firewall (or even if it is really preventing packet loss).

Here are some links I’ve found on the issue:


https://bugs.launchpad.net/ubuntu/+source/linux-lts-raring/+bug/1195474
http://www.brendangregg.com/blog/2014-09-11/perf-kernel-line-tracing.html

Can someone shed any light on this, especially in the context of VyOS specifically?


#2

Hello number_one

This issue already filed on Bugzilla.

Please check this page.
http://bugzilla.vyos.net/show_bug.cgi?id=365


Hiroyuki Sato.


#3

Thanks. Forgot to check there first.