Very slow and inconsistent internal network speed (between VM's on the same host) for FreeBSD 11.0+ as guest on XCP-ng/XenServer

[Christian M]

Den tors 20 juni 2019 kl 16:39 skrev Roger Pau Monné <roger.pau at citrix.com>:

>
> Do you see the same issues with external connections? Have you tested
> throughput between two FreeBSD 12.0 VM running on different hosts?
>
>
I've tested 12.0-RELEASE between two hosts (XCP-ng 7.6.0 and Citrix
CXenserver 7.2.0) over Gbit link, and iperf results is about 600Mbit/s back
and forth.

I also tested 12.0-RELEASE on same XCP-ng host, but changed the network
from Private Network to the Internal Network (that's connected to a PIF).
That increased speed slightly, but It's still below 100mbit back and forth.




>
>
> Hm, OK that's weird, I don't think however it's related to Xen. Have
> you tried if the same happens on a bare-metal install of FreeBSD?
>
> Or when running on a different hypervisor?
>
>
I have not. I only have XCP-ng 7.6.0 and Citrix XenServer 7.x to play with
currently. I have no server at this moment to test a bare metal install on,
but if you believe this is an important test I could perhaps find a machine
to try it on. Please let me know if I should proceed with this.



>
> >
> > Any ideas of how to proceed now to find a solution for this?
>
> Maybe you can try to run wireshark/tcpdump or some other similar
> software in order to try to detect if there are errors on the
> transmitted packets?
>
> You could run the sniffer on the host and attach it to the backend
> interfaces (vifX.X) or the bridge if you are using bridged
> networking.
>
> The 12.0 <-> 12.0 case seems quite bad, so I would start with that
> one.
>
> Roger.
>

I have now run tshark (wireshark) to capture traffic between 12.0 <-> 12.0
on the private network (running tshark on freebsd). I'm really not
qualified to interpret the output, so I'll link to the capture-output here:
capture-output.pcap:
https://drive.google.com/open?id=1zU6qhZO7OOKfLRugXJovYIQuFCLrouH6 (218MB)
output.txt (tshark -r capture-output.pcap > output.txt):
https://drive.google.com/open?id=1ORJy_jhDyAIgmw1WnXBsPQSlIxqEzVrF (34MB)

I'm not really sure how to run it on XCP-ng, or is there perhaps another
tool I can use for that other than tshark?

Thanks,
Christian