Slow networking speeds with Freebsd 12.0 and Xen-4.12.1, freebsd-12.0 as dom0

[Roger Pau Monné]

On Thu, Feb 13, 2020 at 06:58:53PM -0800, Brian Buhrow wrote:
> 	Hello.  I'm noticing that network performance on guest VN's whether
> they're pv or hvm is very slow when using FreeBSD-12.0 as dom0 as compared
> with older versions of Xen and NetBSD as dom0.  For example, 
> I have the following two comparisons, both with the same domu running:
> 
> FreeBSD-12.0/Xen 4.12.1, 60 mbits/sec from the vm in question.

So I've done a small test and using a FreeBSD dom0 with a FreeBSD domU
in HVM mode and I get:

# iperf -c 192.168.1.150
------------------------------------------------------------
Client connecting to 192.168.1.150, TCP port 5001
TCP window size:  113 KByte (default)
------------------------------------------------------------
[  3] local 192.168.1.101 port 12224 connected with 192.168.1.150 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   302 MBytes   253 Mbits/sec

This is using my macbook as an iperf server with a USB-ethernet
adapter (so not professional grade hardware at all).

I'm quite sure speed could be better, we certainly have quite a lot of
room for improvement regarding netfront/netback on FreeBSD, as no one
looked at it for quite some time.

Which OS are you using on the domU?

Can you paste the output of ifconfig from the domU? (I'm mostly
interested in knowing which features the domU is attempting to use)

Thanks, Roger.