[Linux-aus] Request for Qualified Opinion: netperf, iperf, others

[Steve Walsh]

Hello Arjen

On 25/07/17 08:55, Arjen Lentz via linux-aus wrote:
> iperf declares itself more modern and much easier to use, however it appears to be capable of fewer tests (not necessarily an issue for this use case).
> iperf 2 is still around in package repos and is rather old.
> iperf3 is a rewrite and appears active. Good.
>
> Because they all require a server side to talk to, choices need to be made.
> And iperf3 is not backwards compatible so it can not talk with iperf2 servers.

I can't comment on netperf, as it didn't tick the boxes I needed ticked
at the time.

Iperf3 is a project of ESNet (Energy Science Network, think AARNet but
for a specific subnet of the R&E Sector). They have a very different use
case to most people, as they need to confirm their 100Gbps (and above)
links and interconnects are actually capable of doing 100Gbps (and
above). Lots of assumptions occur in that space, like all your links
have jumbo frame support enabled, you're looking at performance stats
for long-running (2-3 day) high bandwidth (90Gbps) transfers.

If you run tests with iperf3 with a card that doesn't have any TCP
offload capabilities, you're going to get poor results. Iperf3 drops
128KB blocks into the send buffer and then walks away and lets the stack
offload stuff do it's thing. Without any form of a stack offload, you'll
likely get I/O bound at 4-5Gbps. With a good offload engine, you can
push 9.5Gbps+ out of a 10Gbps card without breaking a sweat.

If you're looking to see if servers with TOE-support are doing their
thing, iperf3 will probably tick that box. If you're looking to see if
the 1Gbps link you've bough actually does 1Gbps, then iperf2 will tick
the box happily.

It sounds like what you're wanting to end up with is a Ethernet OAM [0]
style testing framework, would that be a safe assumption?

regards

[0]https://en.wikipedia.org/wiki/Operations,_administration_and_management

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