system-traffic.at: Fix flaky DNAT load balancing test.

'conntrack - DNAT load balancing' test fails from time to time
because not all the group buckets are getting hit.

In short, the test creates a group with 3 buckets with the same
weight.  It creates 12 TCP sessions and expects that each bucket
will be used at least once.  However, there is a solid chance that
this will not happen.  The probability of having at least one
empty bucket is:

  C(3, 1) x (2/3)^N - C(3, 2) x (1/3)^N

Where N is the number of distinct TCP sessions.  For N=12, the
probability is about 0.023, i.e. there is a 2.3% chance for a
test to fail, which is not great for CI.

Increasing the number of sessions to 50 to reduce the probability
of failure down to 4.7e-9.  In my testing, the configuration with
50 TCP sessions didn't fail after 6000 runs.  Should be good
enough for CI systems.

Fixes: 2c66ebe47a88 ("ofp-actions: Allow conntrack action in group buckets.")
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Acked-by: Michael Phelan <michael.phelan@intel.com>
Acked-by: Paolo Valerio <pvalerio@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/system-traffic.at b/tests/system-traffic.at
index ea994a40d..66e6d6318 100644
--- a/tests/system-traffic.at
+++ b/tests/system-traffic.at
@@ -5918,7 +5918,7 @@ on_exit 'ovs-appctl revalidator/purge'
 on_exit 'ovs-appctl dpif/dump-flows br0'
 
 dnl Should work with the virtual IP address through NAT
-for i in 1 2 3 4 5 6 7 8 9 10 11 12; do
+for i in $(seq 1 50); do
     echo Request $i
     NS_CHECK_EXEC([at_ns1], [wget 10.1.1.64 -t 5 -T 1 --retry-connrefused -v -o wget$i.log])
 done