test-poll: High failure rate on multi-core FreeBSD guest

[Andrea Bolognani]

Hi,

the test-poll test seems to have a very high failure rate on a
multi-core FreeBSD guest:

$ for i in $(seq 1 10000); do

./tests/test-poll >/dev/null 2>&1
echo $?
done >test-poll.rc

$ grep -c '.*' test-poll.rc
10000
$ grep -c '^0$' test-poll.rc
5
$ grep -c '^1$' test-poll.rc
50
$ grep -c '^2$' test-poll.rc
9945

If I configure the guest to only have a single vCPU rather than
two, then the test succeeds every single time.

Daniel recently had to fix one of libvirt's own test cases[1],
which similarly started failing on FreeBSD as soon as you moved
past one vCPU. Maybe the issue with gnulib's test-poll is related.

Note that libvirt is on d6397dde2e12 at the moment, but updating
to 0d10473be6fb (which is the current master) didn't help.


[1] https://www.redhat.com/archives/libvir-list/2018-May/msg00009.html