Re: Very slow scp performance comparing to Linux [dd to /dev/null shows substantial FreeBSD vs. Ubuntu differences for bs=1k (or 1K) and bs=512]

On Aug 30, 2023, at 20:59, Wei Hu <weh@microsoft.com> wrote:

>> -----Original Message-----
>> From: Mark Millard <marklmi@yahoo.com>
>> Sent: Thursday, August 31, 2023 10:18 AM
>> To: Mark Saad <nonesuch@longcount.org>
>> Cc: Wei Hu <weh@microsoft.com>; FreeBSD Hackers <freebsd-
>> hackers@freebsd.org>
>> Subject: Re: Very slow scp performance comparing to Linux [dd to /dev/null
>> shows substantial FreeBSD vs. Ubuntu differences for bs=1k (or 1K) and
>> bs=512]
>> 
>> On Aug 30, 2023, at 18:45, Mark Saad <nonesuch@longcount.org> wrote:
>> 
>>> All
>>> Why not take scp out of the picture and try iperf? Why , we could be looking
>> at rss by default in Linux .
> 
> Actually I did the iperf3 test as well and posted results a couple days ago. 
> Pasting here:
> 
> FreeBSD iperf3 to localhost, single stream: 30.9 Gb/s 
> Linux iperf3 to localhost, single stream: 48.8 Gb/s

I'll note that (48.8Gb/s) / (30.9Gb/s) is a much
smaller ratio than then either of the originally
reported Ubuntu/FreeBSD ratios:

(550 MB/s) / (70 MB/s)
or:
(350 MB/s) / (70 MB/s)

Suggesting one or more non-network issues are
contributing, especially vs. the localhost test
that had the 550/70 ratio.

> Neither of them has any tcp retry. 
> 
> Both VMs run on Intel(R) Xeon(R) Platinum 8473C (2100.00-MHz K8-class CPU). 
> The FreeBSD VM is 16 vcpu, with 128 GB memory.
> The Linux VM is 4 vcpu, with 32 GB memory.
> 
> Wei
> 
> 
>> 
>> . . .


===
Mark Millard
marklmi at yahoo.com