RE: Very slow scp performance comparing to Linux

Posting the full "iperf3 -i 1" output, as well as "netstat -snp tcp" before and after (or just the delta) would be nice;

On high speed NICs, iperf3 is nowadays typically core-limited (scales with clock speed of the active core where the singular worker thread is running), but that should be pretty much identical to how scp is doing things. On real hardware, it may be tricky to achieve more than 10Gbps or 25Gbps (depending on how modern the platform is) with iperf3.

Also, for high bandwidth operation, a number of NIC drivers typically perform better when tweaking their tx/rs queues:

CC: However, tuning "sysctl net.link.ifqmaxlen" directly does not work. There is a per NIC interface setup in the driver to setup device tx/rx queues. I have to increase the tx queue "ifq_maxlen" from the device sysctl "hw.bce.tx_pages". After tuning that, I can achieve a stable 1Gbps x 100ms delay BDP.


Richard Scheffenegger


-----Original Message-----
From: owner-freebsd-net@freebsd.org <owner-freebsd-net@freebsd.org> On Behalf Of mike tancsa
Sent: Montag, 28. August 2023 16:02
To: Wei Hu <weh@microsoft.com>; freebsd-hackers@FreeBSD.org
Cc: freebsd-net@FreeBSD.org
Subject: Re: Very slow scp performance comparing to Linux



On 8/28/2023 3:32 AM, Wei Hu wrote:
> Hi,
>
> When I was testing a new NIC, I found the single stream scp performance was almost 8 time slower than Linux on the RX side. Initially I thought it might be something with the NIC. But when I switched to sending the file on localhost, the numbers stay the same.
>
Just curious, how does iperf3 perform in comparison ?

      ---Mike