Re: [Xen-users] Xen 10GBit Ethernet network performance (was: Re: Experience with Xen & AMD Opteron 4200 series?)

[Joseph Glanville <joseph.glanville@xxxxxxxxxxxxxx>]

On 1 July 2012 20:29, Mark van Dijk <lists+xen@xxxxxxxxxxxxxx> wrote:
>> Hey "internecto.net",
>
> Urgh, sorry, I use tags for my list subscriptions (e.g. lists+xen,
> lists+zsh etc.) to ease delivery to imap folders. Unfortunately I can't
> set a default From header with each list so have to do that manually.
>
>> >> - do NOT configure a bridge in dom0, try normal eth0 <-> eth0 comms
>> >>   (The linux bridge is a BRIDGE. that's the things everyone stopped
>> >> using in 1998)
>> >
>> > can you back this up with evidence?
>>
>> I think he meant multiport reapeaters aka hubs.
>
> Yes, now that is something I can agree with although I still don't
> really understand why this comment would apply to virtual bridging.
>
> Mark

Yeah I think he doesn't understand that the linux bridge module is
actually a MAC learning switch.


>
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To drop in a my piece on OpenvSwitch:

Performance of OpenvSwitch is on par with the Linux bridge module.
The main differences is the flow based rules, json-rpc api etc.

Benefits of OpenvSwitch are really about programatically altering
traffic based on these flow rules.
If you are a networking nut and have a good reason to do crazy stuff
with L7 inspection then this is nice.

On the other hand OpenvSwitch doesn't interact with the rest of the
Linux kernel networking ecosystem..
For instance you can't do Layer 2 filtering as easily as you can with
ebtables(the bridge-netfilter module).
Nor can it integrate as nicely with Linux gre/ip-ip tunnels etc.
This is changing slowly with OpenvSwitch going upstream.. we are
likely to see the GRE implementation from OVS merged with the mainline
code.

IMO unless you know what you want OVS for (say easy VLAN tagging) then
you probably don't need it and are better off with the linux bridge.

In terms of Linux bridging module performance... I can easily do 20
odd gigabits between VMs on the same host and can push around 13
gigabits between hosts (40gig infinbiand).
It's worth noting that with both OVS and the bridge module you will be
limited by PPS (packets per second) rather than throughput.
With very big MTUs ( I am using 64k over IB ) one can do many
gigabits, but using 1500 byte MTUs throughput drops below 3gigabits.
This is due to the max throughput of the both the linux bridge module
and OVS on a single core maxes out a a few 100k PPS.

Joseph.

-- 
CTO | Orion Virtualisation Solutions | www.orionvm.com.au
Phone: 1300 56 99 52 | Mobile: 0428 754 846

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