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UpTheCreek
Asked: 2014-11-28 00:28:49 +0800 CST

What is causing `skb rides the rocket` errors?

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On one of our busy (virtual) Debian 6 servers we are seeing a lot of messages in the syslog like this:

kernel: xen_netfront: xennet: skb rides the rocket: 19 slots

We are seeing some connectivity problems, and I believe it's possibly related to this. I've tried researching the issue, but can find very little information (but have confirmed that it can cause packet loss). I'm hoping that someone on here knows more about this issue.

What might be causing this issue?

Could this be a problem with the virtual host? (and why is Xen mentioned here)

What can I do to stop this happening?

Thank you.

networking

1 Answers

  1. From this article: https://bugs.launchpad.net/ubuntu/+source/linux-lts-raring/+bug/1195474 It seems that it is the result of packet loss, due to a kernel bug in linux.

    They offer the suggestion of turning off packet segmentation via "ethtool -K eth0 sg off" but I'm not clear if it's on the host or guest that it should be applied. I just tried it on my own VPS since I'm having the same issue. I hope that helps.

    Stefan Bader (smb) wrote on 2014-05-15: #9 We finally have a way to reproduce this at will. It turns out that any kernel newer than 3.7 (which > > has the change to handle compound pages that I mentioned in comment #7) will suffer from this problem. > The work-around that Brian found in the previous comment will indeed work as it prevents the use of of > fragments (A "ethtool -K eth0 sg off" should be enough). I will mark this bug as a duplicate of the newer one since that already has more detail info.

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