[CentOS] Centos 7 as gateway - UDP performance is busted/awful?

Thu Aug 14 19:09:44 UTC 2014
Les Mikesell <lesmikesell at gmail.com>

On Thu, Aug 14, 2014 at 1:53 PM, Tom Horsley <horsley1953 at gmail.com> wrote:
>
>> I thought NFS defaulted to writing 8192 blocks and let the network
>> stack fragment as needed
>
> I think it is those fragments I'm looking at in wireshark.
>
> I just did another experiment - If I mount the same NFS
> filesystem on the centos 7 host, and do the same "ls"
> command, it works perfectly and the wireshark trace shows
> the same 1516 capture length for the NFS readdir messages.
>
> Somehow it is just the idea of forwarding the UDP packets
> to the virtual machine that the host objects to. The exact
> same size packets destined for it to use directly have no
> problems.

Seems like a horrible thing to do, but does it fix it if you mount with
rsize=1500, wsize=1500 - or maybe 1484?

Are you just bridging to the NIC interface?   I don't see why that
would need to change the packets at all.   What happens if you ping
with a large -s value through the bridge (host or external box to
guest)?

-- 
   Les Mikesell
      lesmikesell at gmail.com