Suboptimal iperf3 performance on RockPro64

[Jason Mitchell <jmitchel%bigjar.com@localhost>]

Hello,

I have a project where I need to be able to saturate a gigabit link. I’m 
using a RockPro64 running 9.0_STABLE. I’m using an Intel i210 PCI-e NIC 
and I can’t get more than 740Mbit/sec on iperf3. I’ve enabled tcp4csum, 
udp4csum & ip4csum offloading and I’ve set the CPU speeds to max (1416 
for the Cortex-A53’s and 1800 for the Cortex-A72’s).

I’ve had iostat -C running and the CPU is never more than 34% busy. 
vmstat shows 99 interrupts/sec. netstat doesn’t show any errors or 
collisions.

In contrast a 7 year old laptop with a chip that is >50% slower (on 
Geekbench5) can do 880Mbit/sec. The CPU usage peaks at 66% and there are 
also 99 interrupts/sec. The nic is from RealTek (re).

Also an AMD powered micro PC with similar but somewhat worse CPU stats  
gets 920Mbit/second also with a RealTek nic (re).

Intuitively it seems like the RockPro64 should be able to push more 
across the network. I’ve ordered a microPC which has a PCI-e slot and a 
much slower CPU so I’ll be able to move the NIC from one machine to 
another and test.

But before that microPC arrives, does anyone have an idea? Or what more 
tests can I do to troubleshoot this further?

Thanks,

Jason M.