[9.2] Neutron QoS bandwith is lower than expected

[Yury Tregubov]

Since about 9.2 snapshot #541 the following scenario is failed on step #9
        """Check traffic restriction between vm for different max-burst
            parameter

            Scenario:
                1. Create net01, subnet
                2. Create router01, set gateway and add interface to net01
                3. Create new policy: neutron qos-policy-create policy_1
                4. Create new rule:
                    neutron qos-bandwidth-limit-rule-create rule-id policy_1 \
                    --max-kbps 4000 --max-burst-kbps 300
                5. Update net01 with --qos-policy parameter
                6. Boot ubuntu vm1 in net01 on compute-1
                7. Boot ubuntu vm2 in net01 on compute-1
                8. Start iperf between vm1 and vm2
                9. Check that egress traffic on vm1 must be eq
                    --max-kbps + --max-burst
                10. Update rule for vm port:
                    neutron qos-bandwidth-limit-rule-update rule-id bw-limiter \
                    --max-kbps 6000 --max-burst-kbps 500
                9. Check that egress traffic on vm1 must be eq
                    --max-kbps + --max-burst
            """

Expected amount of traffic is 4403200. But got only 1363148.

Test log example is: http://172.18.173.8:8080/jenkins/view/MOS-INT%209.X/job/9.x_VxLAN/172/testReport/junit/mos_tests.neutron.python_tests.test_qos/TestSingleCompute/test_traffic_restriction_with_max_burst__838298__/

Diagnostic snapshot is: https://drive.google.com/a/mirantis.com/file/d/0B1Crk-sAvGanYWp2czBTV1NuZ1k/view?usp=sharing

[Yury Tregubov (ytregubov)]

Diagnostic snapshot is: https://drive.google.com/a/mirantis.com/file/d/0B1Crk-sAvGanYWp2czBTV1NuZ1k/view?usp=sharing

[Alexander Ignatov (aignatov)]

@Yury Tregubov, I've looked at sources of test "'838298'" here https://github.com/Mirantis/mos-integration-tests and may say that initial assumption in test that bandwidth is near to infinity is wrong.

Before any enablement of any value of any qos policy in test you have to check initial bandwidth of networks you are using in your test setup. It means that in scenario "'838298'" before step 1 you need to measure current network bandwidth otherwise this test will always fail if initial bandwidth was lower than the value (4000 in test case) in qos policy since initial bw never gets higher and it doesn't depend on qos values. It depends on hardware and openstack configurations like different MTU values, jumbo frames enables, type of segmentation (vlans, vxlans), other datapath acceleration techniques.

[Alexander Ignatov (aignatov)]

Moved this bug to mos qa since testcase is Invalid in its current logic.