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

[Eugene Grosbein]

25.06.2019 19:40, Christian M wrote:

> I've disabled them all on both VM's with FreeBSD 12.0-RELEASE (ifconfig xn0
> -txcsum -rxcsum -lro -tso), and also tried disabling everything for the VIF
> via XCP-ng earlier. It made no difference unfortunately.

Then you should try to bring the interface to promiscuous mode manually
with "ifconfig xn0 promisc" any retry. If this does not make a difference,
then you may be facing some timekeeping problem as tcpdump makes additional
CPU load on the system that can force scheduler behaviour to change.

As next step, you should check your kern.timecounter.* and kern.eventtimer.* sysctls.
If default value of kern.eventtimer.periodic is 0 (it depends on detected "hardware"),
you should change it kern.eventtimer.periodic=1 and retry the test.