From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@qumranet.com>
Subject: Re: Network Overruns
Date: Sat, 13 Sep 2008 08:09:56 +0300
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To: Henri Cook <kvm@theplayboymansion.net>
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Henri Cook wrote:
> Hi all,
>
> I'm running ~13 virtual machines in production on KVM 62 (unfortunately
> the best ubuntu-stable can provide for me :/) and i've noticed a lot of
> TX overruns, is this something i should be worried about? Are my
> machines losing data?
>   

There shouldn't be any data loss, since the guest expects the network to
be lossy.  But this can cause performance drops due to retries.

Most likely the guest's rx queue length is greater than the host's.  You
might try

   ifconfig vnet0 txqueuelen 1500

(and so on for every interface)


or perhaps reducing the guests' txqueuelen.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.