From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: Poor TCP bandwidth between network namespaces
Date: Fri, 08 Feb 2013 18:17:10 -0800
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Cc: Emmanuel Jeanvoine <emmanuel.jeanvoine@inria.fr>,
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On Fri, 2013-02-08 at 17:33 -0800, Eric Dumazet wrote:

> Another thing to consider is the default MTU value :
> 
> 65536 for lo, and 1500 for veth
> 
> It easily explains half performance for veth
> 
> One another thing is the tx-nocache-copy setting, this can explain some
> extra percents.

By the way I get crashes when doing :

# ip link add name veth1 type veth peer name veth0
# rmmod veth

I'll submit a patch.