[ovs-discuss] [OVN] ovn-controller Incremental Processing scale testing

Numan Siddique nusiddiq at redhat.com
Fri Jul 19 19:37:33 UTC 2019


On Fri, Jul 19, 2019 at 6:19 PM Numan Siddique <nusiddiq at redhat.com> wrote:

>
>
> On Fri, Jul 19, 2019 at 6:28 AM Han Zhou <zhouhan at gmail.com> wrote:
>
>>
>>
>> On Tue, Jul 9, 2019 at 12:13 AM Numan Siddique <nusiddiq at redhat.com>
>> wrote:
>> >
>> >
>> >
>> > On Tue, Jul 9, 2019 at 12:25 PM Daniel Alvarez Sanchez <
>> dalvarez at redhat.com> wrote:
>> >>
>> >> Thanks Numan for running these tests outside OpenStack!
>> >>
>> >> On Tue, Jul 9, 2019 at 7:50 AM Numan Siddique <nusiddiq at redhat.com>
>> wrote:
>> >> >
>> >> >
>> >> >
>> >> > On Tue, Jul 9, 2019 at 11:05 AM Han Zhou <zhouhan at gmail.com> wrote:
>> >> >>
>> >> >>
>> >> >>
>> >> >> On Fri, Jun 21, 2019 at 12:31 AM Han Zhou <zhouhan at gmail.com>
>> wrote:
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> > On Thu, Jun 20, 2019 at 11:42 PM Numan Siddique <
>> nusiddiq at redhat.com> wrote:
>> >> >> > >
>> >> >> > >
>> >> >> > >
>> >> >> > > On Fri, Jun 21, 2019, 11:47 AM Han Zhou <zhouhan at gmail.com>
>> wrote:
>> >> >> > >>
>> >> >> > >>
>> >> >> > >>
>> >> >> > >> On Tue, Jun 11, 2019 at 9:16 AM Daniel Alvarez Sanchez <
>> dalvarez at redhat.com> wrote:
>> >> >> > >> >
>> >> >> > >> > Thanks a lot Han for the answer!
>> >> >> > >> >
>> >> >> > >> > On Tue, Jun 11, 2019 at 5:57 PM Han Zhou <zhouhan at gmail.com>
>> wrote:
>> >> >> > >> > >
>> >> >> > >> > >
>> >> >> > >> > >
>> >> >> > >> > >
>> >> >> > >> > > On Tue, Jun 11, 2019 at 5:12 AM Dumitru Ceara <
>> dceara at redhat.com> wrote:
>> >> >> > >> > > >
>> >> >> > >> > > > On Tue, Jun 11, 2019 at 10:40 AM Daniel Alvarez Sanchez
>> >> >> > >> > > > <dalvarez at redhat.com> wrote:
>> >> >> > >> > > > >
>> >> >> > >> > > > > Hi Han, all,
>> >> >> > >> > > > >
>> >> >> > >> > > > > Lucas, Numan and I have been doing some 'scale'
>> testing of OpenStack
>> >> >> > >> > > > > using OVN and wanted to present some results and
>> issues that we've
>> >> >> > >> > > > > found with the Incremental Processing feature in
>> ovn-controller. Below
>> >> >> > >> > > > > is the scenario that we executed:
>> >> >> > >> > > > >
>> >> >> > >> > > > > * 7 baremetal nodes setup: 3 controllers (running
>> >> >> > >> > > > > ovn-northd/ovsdb-servers in A/P with pacemaker) + 4
>> compute nodes. OVS
>> >> >> > >> > > > > 2.10.
>> >> >> > >> > > > > * The test consists on:
>> >> >> > >> > > > >   - Create openstack network (OVN LS), subnet and
>> router
>> >> >> > >> > > > >   - Attach subnet to the router and set gw to the
>> external network
>> >> >> > >> > > > >   - Create an OpenStack port and apply a Security
>> Group (ACLs to allow
>> >> >> > >> > > > > UDP, SSH and ICMP).
>> >> >> > >> > > > >   - Bind the port to one of the 4 compute nodes
>> (randomly) by
>> >> >> > >> > > > > attaching it to a network namespace.
>> >> >> > >> > > > >   - Wait for the port to be ACTIVE in Neutron ('up ==
>> True' in NB)
>> >> >> > >> > > > >   - Wait until the test can ping the port
>> >> >> > >> > > > > * Running browbeat/rally with 16 simultaneous process
>> to execute the
>> >> >> > >> > > > > test above 150 times.
>> >> >> > >> > > > > * When all the 150 'fake VMs' are created, browbeat
>> will delete all
>> >> >> > >> > > > > the OpenStack/OVN resources.
>> >> >> > >> > > > >
>> >> >> > >> > > > > We first tried with OVS/OVN 2.10 and pulled some
>> results which showed
>> >> >> > >> > > > > 100% success but ovn-controller is quite loaded (as
>> expected) in all
>> >> >> > >> > > > > the nodes especially during the deletion phase:
>> >> >> > >> > > > >
>> >> >> > >> > > > > - Compute node: https://imgur.com/a/tzxfrIR
>> >> >> > >> > > > > - Controller node (ovn-northd and ovsdb-servers):
>> https://imgur.com/a/8ffKKYF
>> >> >> > >> > > > >
>> >> >> > >> > > > > After conducting the tests above, we replaced
>> ovn-controller in all 7
>> >> >> > >> > > > > nodes by the one with the current master branch
>> (actually from last
>> >> >> > >> > > > > week). We also replaced ovn-northd and ovsdb-servers
>> but the
>> >> >> > >> > > > > ovs-vswitchd has been left untouched (still on 2.10).
>> The expected
>> >> >> > >> > > > > results were to get less ovn-controller CPU usage and
>> also better
>> >> >> > >> > > > > times due to the Incremental Processing feature
>> introduced recently.
>> >> >> > >> > > > > However, the results don't look very good:
>> >> >> > >> > > > >
>> >> >> > >> > > > > - Compute node: https://imgur.com/a/wuq87F1
>> >> >> > >> > > > > - Controller node (ovn-northd and ovsdb-servers):
>> https://imgur.com/a/99kiyDp
>> >> >> > >> > > > >
>> >> >> > >> > > > > One thing that we can tell from the ovs-vswitchd CPU
>> consumption is
>> >> >> > >> > > > > that it's much less in the Incremental Processing (IP)
>> case which
>> >> >> > >> > > > > apparently doesn't make much sense. This led us to
>> think that perhaps
>> >> >> > >> > > > > ovn-controller was not installing the necessary flows
>> in the switch
>> >> >> > >> > > > > and we confirmed this hypothesis by looking into the
>> dataplane
>> >> >> > >> > > > > results. Out of the 150 VMs, 10% of them were
>> unreachable via ping
>> >> >> > >> > > > > when using ovn-controller from master.
>> >> >> > >> > > > >
>> >> >> > >> > > > > @Han, others, do you have any ideas as of what could
>> be happening
>> >> >> > >> > > > > here? We'll be able to use this setup for a few more
>> days so let me
>> >> >> > >> > > > > know if you want us to pull some other data/traces, ...
>> >> >> > >> > > > >
>> >> >> > >> > > > > Some other interesting things:
>> >> >> > >> > > > > On each of the compute nodes, (with an almost evenly
>> distributed
>> >> >> > >> > > > > number of logical ports bound to them), the max amount
>> of logical
>> >> >> > >> > > > > flows in br-int is ~90K (by the end of the test, right
>> before deleting
>> >> >> > >> > > > > the resources).
>> >> >> > >> > > > >
>> >> >> > >> > > > > It looks like with the IP version, ovn-controller
>> leaks some memory:
>> >> >> > >> > > > > https://imgur.com/a/trQrhWd
>> >> >> > >> > > > > While with OVS 2.10, it remains pretty flat during the
>> test:
>> >> >> > >> > > > > https://imgur.com/a/KCkIT4O
>> >> >> > >> > > >
>> >> >> > >> > > > Hi Daniel, Han,
>> >> >> > >> > > >
>> >> >> > >> > > > I just sent a small patch for the ovn-controller memory
>> leak:
>> >> >> > >> > > > https://patchwork.ozlabs.org/patch/1113758/
>> >> >> > >> > > >
>> >> >> > >> > > > At least on my setup this is what valgrind was pointing
>> at.
>> >> >> > >> > > >
>> >> >> > >> > > > Cheers,
>> >> >> > >> > > > Dumitru
>> >> >> > >> > > >
>> >> >> > >> > > > >
>> >> >> > >> > > > > Looking forward to hearing back :)
>> >> >> > >> > > > > Daniel
>> >> >> > >> > > > >
>> >> >> > >> > > > > PS. Sorry for my previous email, I sent it by mistake
>> without the subject
>> >> >> > >> > > > > _______________________________________________
>> >> >> > >> > > > > discuss mailing list
>> >> >> > >> > > > > discuss at openvswitch.org
>> >> >> > >> > > > >
>> https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
>> >> >> > >> > >
>> >> >> > >> > > Thanks Daniel for the testing and reporting, and thanks
>> Dumitru for fixing the memory leak.
>> >> >> > >> > >
>> >> >> > >> > > Currently ovn-controller incremental processing only
>> handles below SB changes incrementally:
>> >> >> > >> > > - logical_flow
>> >> >> > >> > > - port_binding (for regular VIF binding NOT on current
>> chassis)
>> >> >> > >> > > - mc_group
>> >> >> > >> > > - address_set
>> >> >> > >> > > - port_group
>> >> >> > >> > > - mac_binding
>> >> >> > >> > >
>> >> >> > >> > > So, in test scenario you described, since each iteration
>> creates network (SB datapath changes) and router ports (port_binding
>> changes for non VIF), the incremental processing would not help much,
>> because most steps in your test should trigger recompute. It would help if
>> you create more Fake VMs in each iteration, e.g. create 10 VMs or more on
>> each LS. Secondly, when VIF port-binding happens on current chassis, the
>> ovn-controller will still do re-compute, and because you have only 4
>> compute nodes, so 1/4 of the compute node will still recompute even when
>> binding a regular VIF port. When you have more compute nodes you would see
>> incremental processing more effective.
>> >> >> > >> >
>> >> >> > >> > Got it, it makes sense (although then worst case, it should
>> be at
>> >> >> > >> > least what we had before and not worse but it can also be
>> because
>> >> >> > >> > we're mixing version here: 2.10 vs master).
>> >> >> > >> > >
>> >> >> > >> > > However, what really worries me is the 10% VM unreachable.
>> I have one confusion here on the test steps. The last step you described
>> was: - Wait until the test can ping the port. So if the VM is not pingable
>> the test won't continue?
>> >> >> > >> >
>> >> >> > >> > Sorry I should've explained it better. We wait for 2 minutes
>> to the
>> >> >> > >> > port to respond to pings, if it's not reachable then we
>> continue with
>> >> >> > >> > the next port (16 rally processes are running simultaneously
>> so the
>> >> >> > >> > rest of the process may be doing stuff at the same time).
>> >> >> > >> >
>> >> >> > >> > >
>> >> >> > >> > > To debug the problem, the first thing is to identify what
>> flows are missing for the VMs that is unreachable. Could you do ovs-appctl
>> ofproto/trace for the ICMP flow of any VM with ping failure? And then,
>> please enable debug log for ovn-controller with ovs-appctl -t
>> ovn-controller vlog/set file:dbg. There may be too many logs so please
>> enable it for as short time as any VM with ping failure is reproduced. If
>> the last step "wait until the test can ping the port" is there then it
>> should be able to detect the first occurrence if the VM is not reachable in
>> e.g. 30 sec.
>> >> >> > >> >
>> >> >> > >> > We'll need to hack a bit here but let's see :)
>> >> >> > >> > >
>> >> >> > >> > > In the ovn-scale-test we didn't have data plane test, but
>> this problem was not seen in our live environment either, with a far larger
>> scale. The major difference in your test v.s. our environment are:
>> >> >> > >> > > - We are runing with an older version. So there might be
>> some rebase/refactor problem caused this. To eliminate this, I'd suggest to
>> try a branch I created for 2.10 (
>> https://github.com/hzhou8/ovs/tree/ip12_rebase_on_2.10), which matches
>> the base test you did which is also 2.10. It may also eliminate
>> compatibility problem, if there is any, between OVN master branch and OVS
>> 2.10 as you mentioned is used in the test.
>> >> >> > >> > > - We don't use Security Group (I guess the  ~90k OVS flows
>> you mentioned were mainly introduced by the Security Group use, if all
>> ports were put in same group). The incremental processing is expected to be
>> correct for security-groups, and handling it incrementally because of
>> address_set and port_group incremental processing. However, since the
>> testing only relied on the regression tests, I am not 100% sure if the test
>> coverage was sufficient. So could you try disabling Security Group to rule
>> out the problem?
>> >> >> > >> >
>> >> >> > >> > Ok will try to repeat the tests without the SGs.
>> >> >> > >> > >
>> >> >> > >> > > Thanks,
>> >> >> > >> > > Han
>> >> >> > >> >
>> >> >> > >> > Thanks once again!
>> >> >> > >> > Daniel
>> >> >> > >>
>> >> >> > >> Hi Daniel,
>> >> >> > >>
>> >> >> > >> Any updates? Do you still see the 10% VM unreachable
>> >> >> > >>
>> >> >> > >>
>> >> >> > >> Thanks,
>> >> >> > >> Han
>> >> >> > >
>> >> >> > >
>> >> >> > > Hi Han,
>> >> >> > >
>> >> >> > > As such there is no datapath impact. After increasing the ping
>> wait timeout value from 120 seconds to 180 seconds its 100% now.
>> >> >> > >
>> >> >> > > But the time taken to program the flows is too huge when
>> compared to OVN master without IP patches.
>> >> >> > > Here is some data -  http://paste.openstack.org/show/753224/
>> .  I am still investigating it. I will update my findings in some time.
>> >> >> > >
>> >> >> > > Please see the times for the action - vm.wait_for_ping
>> >> >> > >
>> >> >> >
>> >> >> > Thanks Numan for the investigation and update. Glad to hear there
>> is no correctness issue, but sorry for the slowness in your test scenario.
>> I expect that the operations in your test trigger recomputing and the worst
>> case should be similar performance as withour I-P. It is weird that it
>> turned out so much slower in your test. There can be some extra overhead
>> when it tries to do incremental processing and then fallback to full
>> recompute, but it shouldn't cause that big difference. It might be that for
>> some reason the main loop iteration is triggered more times unnecessarily.
>> I'd suggest to compare the coverage counter "lflow_run" between the tests,
>> and also check perf report to see if the hotspot is somewhere else. (Sorry
>> that I can't provide full-time help now since I am still on vacation but I
>> will try to be useful if things are blocked)
>> >> >>
>> >> >> Hi Numan/Daniel, do you have any new findings on why I-P got worse
>> result in your test? The extremely long latency (2 - 3 min) shown in your
>> report reminds me a similar problem I reported before:
>> https://mail.openvswitch.org/pipermail/ovs-dev/2018-April/346321.html
>> >> >>
>> >> >> The root cause of that problem was still not clear. In that report,
>> the extremely long latency (7 min) was observed without I-P and it didn't
>> happen with I-P. If it is the same problem, then I suspect it is not
>> related to I-P or non I-P, but some problem related to ovsdb monitor
>> condition change. To confirm if it is same problem, could you:
>> >> >> 1. pause the test when the scale is big enough (e.g. when the test
>> is almost completed), and then
>> >> >> 2. enable ovn-controller debug log, and then
>> >> >> 3. run one more iteration of the test, and see if the time was
>> spent on waiting for SB DB update notification.
>> >> >>
>> >> >> Please ignore my speculation above if you already found the root
>> cause and it would be great if you could share it :)
>> >> >
>> >> >
>> >> > Thanks for sharing this Han.
>> >> >
>> >> > I do not have any new findings. Yesterday I ran ovn-scale-test
>> comparing OVN with IP vs without IP (using the master branch).
>> >> > The test creates a new logical switch, adds it to a router, few ACLs
>> and creates 2 logical ports and pings between them.
>> >> > I am using physical deployment which creates actual namespaces
>> instead of sandboxes.
>> >> >
>> >> > The results doesn't show any huge difference between the two.
>> >> 2300 vs 2900 seconds total time or  44 vs 56 seconds for the 95%ile?
>> >> It is not negligible IMHO. It's a >25% penalty with the IP. Maybe I
>> >> missed something from the results?
>> >>
>> >
>> > Initially I ran with ovn-nbctl running commands as one batch (ie
>> combining commands with "--"). The results were very similar. Like this one
>> >
>> > *******
>> >
>> > With non IP - ovn-nbctl NO daemon mode
>> >
>> >
>> +--------------------------------------------------------------------------------------------------------------+
>> > |                                             Response Times (sec)
>>                                         |
>> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> > | action                                | min   | median | 90%ile |
>> 95%ile | max    | avg    | success | count |
>> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> > | ovn_network.create_routers            | 0.288 | 0.429  | 5.454  |
>> 5.538  | 20.531 | 1.523  | 100.0%  | 1000  |
>> > | ovn.create_lswitch                    | 0.046 | 0.139  | 0.202  |
>> 5.084  | 10.259 | 0.441  | 100.0%  | 1000  |
>> > | ovn_network.connect_network_to_router | 0.164 | 0.411  | 5.307  |
>> 5.491  | 15.636 | 1.128  | 100.0%  | 1000  |
>> > | ovn.create_lport                      | 0.11  | 0.272  | 0.478  |
>> 5.284  | 15.496 | 0.835  | 100.0%  | 1000  |
>> > | ovn_network.bind_port                 | 1.302 | 2.367  | 2.834  |
>> 3.24   | 12.409 | 2.527  | 100.0%  | 1000  |
>> > | ovn_network.wait_port_up              | 0.0   | 0.001  | 0.001  |
>> 0.001  | 0.002  | 0.001  | 100.0%  | 1000  |
>> > | ovn_network.ping_ports                | 0.04  | 10.24  | 10.397 |
>> 10.449 | 10.82  | 6.767  | 100.0%  | 1000  |
>> > | total                                 | 2.219 | 13.903 | 23.068 |
>> 24.538 | 49.437 | 13.222 | 100.0%  | 1000  |
>> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> >
>> >
>> > With IP - ovn-nbctl NO daemon mode
>> >
>> > concurrency - 10
>> >
>> >
>> +--------------------------------------------------------------------------------------------------------------+
>> > |                                             Response Times (sec)
>>                                         |
>> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> > | action                                | min   | median | 90%ile |
>> 95%ile | max    | avg    | success | count |
>> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> > | ovn_network.create_routers            | 0.274 | 0.402  | 0.493  |
>> 0.51   | 0.584  | 0.408  | 100.0%  | 1000  |
>> > | ovn.create_lswitch                    | 0.064 | 0.137  | 0.213  |
>> 0.244  | 0.33   | 0.146  | 100.0%  | 1000  |
>> > | ovn_network.connect_network_to_router | 0.203 | 0.395  | 0.677  |
>> 0.766  | 0.912  | 0.427  | 100.0%  | 1000  |
>> > | ovn.create_lport                      | 0.13  | 0.261  | 0.437  |
>> 0.497  | 0.604  | 0.283  | 100.0%  | 1000  |
>> > | ovn_network.bind_port                 | 1.307 | 2.374  | 2.816  |
>> 2.904  | 3.401  | 2.325  | 100.0%  | 1000  |
>> > | ovn_network.wait_port_up              | 0.0   | 0.001  | 0.001  |
>> 0.001  | 0.002  | 0.001  | 100.0%  | 1000  |
>> > | ovn_network.ping_ports                | 0.028 | 10.237 | 10.422 |
>> 10.474 | 11.281 | 6.453  | 100.0%  | 1000  |
>> > | total                                 | 2.251 | 13.631 | 14.822 |
>> 15.008 | 15.901 | 10.044 | 100.0%  | 1000  |
>> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> >
>> > *****************
>> >
>> > The results I shared in the previous email were with  ACLs added and
>> ovn-nbctl - batch mode disabled.
>> >
>> > I agree with you. Let me do few more runs to be sure that the results
>> are consistent.
>> >
>> > Thanks
>> > Numan
>> >
>> >
>> >> > I will test with OVN 2.9 vs 2.11 master along with what you have
>> suggested above and see if there are any problems related to ovsdb monitor
>> condition change.
>> >> >
>> >> > Thanks
>> >> > Numan
>> >> >
>> >> > Below are the results
>> >> >
>> >> >
>> >> > With IP master - nbctl daemon node - No batch mode
>> >> > concurrency - 10
>> >> >
>> >> >
>> +--------------------------------------------------------------------------------------------------------------+
>> >> > |                                             Response Times (sec)
>>                                           |
>> >> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> >> > | action                                | min   | median | 90%ile |
>> 95%ile | max    | avg    | success | count |
>> >> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> >> > | ovn_network.create_routers            | 0.269 | 0.661  | 10.426 |
>> 15.422 | 37.259 | 3.721  | 100.0%  | 1000  |
>> >> > | ovn.create_lswitch                    | 0.313 | 0.45   | 12.107 |
>> 15.373 | 30.405 | 4.185  | 100.0%  | 1000  |
>> >> > | ovn_network.connect_network_to_router | 0.163 | 0.255  | 10.121 |
>> 10.64  | 20.475 | 2.655  | 100.0%  | 1000  |
>> >> > | ovn.create_lport                      | 0.351 | 0.514  | 12.255 |
>> 15.511 | 34.74  | 4.621  | 100.0%  | 1000  |
>> >> > | ovn_network.bind_port                 | 1.362 | 2.447  | 7.34   |
>> 7.651  | 17.651 | 3.146  | 100.0%  | 1000  |
>> >> > | ovn_network.wait_port_up              | 0.086 | 2.734  | 5.272  |
>> 7.827  | 22.717 | 2.957  | 100.0%  | 1000  |
>> >> > | ovn_network.ping_ports                | 0.038 | 10.196 | 20.285 |
>> 20.39  | 40.74  | 7.52   | 100.0%  | 1000  |
>> >> > | total                                 | 2.862 | 27.267 | 49.956 |
>> 56.39  | 90.884 | 28.808 | 100.0%  | 1000  |
>> >> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> >> > Load duration: 2950.4133141
>> >> > Full duration: 2951.58845997 seconds
>> >> >
>> >> > ***********
>> >> > With non IP - nbctl daemin node -ACLs - No batch mode
>> >> >
>> >> > concurrency - 10
>> >> >
>> >> >
>> +--------------------------------------------------------------------------------------------------------------+
>> >> > |                                             Response Times (sec)
>>                                           |
>> >> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> >> > | action                                | min   | median | 90%ile |
>> 95%ile | max    | avg    | success | count |
>> >> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> >> > | ovn_network.create_routers            | 0.267 | 0.421  | 10.395 |
>> 10.735 | 25.501 | 3.09   | 100.0%  | 1000  |
>> >> > | ovn.create_lswitch                    | 0.314 | 0.408  | 10.331 |
>> 10.483 | 25.357 | 3.049  | 100.0%  | 1000  |
>> >> > | ovn_network.connect_network_to_router | 0.153 | 0.249  | 6.552  |
>> 10.268 | 20.545 | 2.236  | 100.0%  | 1000  |
>> >> > | ovn.create_lport                      | 0.344 | 0.49   | 10.566 |
>> 15.428 | 25.542 | 3.906  | 100.0%  | 1000  |
>> >> > | ovn_network.bind_port                 | 1.372 | 2.409  | 7.437  |
>> 7.665  | 17.518 | 3.192  | 100.0%  | 1000  |
>> >> > | ovn_network.wait_port_up              | 0.086 | 1.323  | 5.157  |
>> 7.769  | 20.166 | 2.291  | 100.0%  | 1000  |
>> >> > | ovn_network.ping_ports                | 0.034 | 2.077  | 10.347 |
>> 10.427 | 20.307 | 5.123  | 100.0%  | 1000  |
>> >> > | total                                 | 3.109 | 21.26  | 39.245 |
>> 44.495 | 70.197 | 22.889 | 100.0%  | 1000  |
>> >> >
>> +---------------------------------------+-------+--------+--------+--------+--------+--------+---------+-------+
>> >> > Load duration: 2328.11378407
>> >> > Full duration: 2334.43504095 seconds
>> >> >
>> >>
>>
>> Hi Numan/Daniel,
>>
>> I spent some time investigating this problem you reported. Thanks Numan
>> for the offline help sharing the details.
>>
>> Although I still didn't reproduce the slowness in my current single node
>> testing env with almost same steps and ACLs shared by Numan, I think I may
>> have figured out a highy probable cause of what you have seen.
>>
>> Here is my theory: there is a difference between the I-P and non-I-P in
>> the main loop. The non-I-P version checks ofctrl_can_put() before doing any
>> flow computation (which is introduced to solve a serious performance
>> problem when there are many OVS flows on a single node, see [1]). When
>> worked out the I-P version, I found this may not be the best approach,
>> since there can be new incremental changes coming and we want to process
>> them in current iteration incrementally, so that we don't need to fallback
>> to recompute in next iteration. So this logic is changed so that we always
>> prioritize computing new changes and keeping the desired flow table up to
>> date, while the in-flight messages to ovs-vswitchd may still pending for an
>> older version of desired state. In the end the final desired state will be
>> synced again to ovs-vswitchd. If there are new changes that triggers
>> recompute again, the recompute (which is always slow) will slow down the
>> ofctrl_run() which keeps sending old pending messages to ovs-vswitchd by
>> the same main thread. (But it won't cause the original performance problem
>> any more because incremental processing engine will not recompute when
>> there is no input change).
>>
>> However, when the test scenario triggers recompute frequently, each
>> single change may take longer to be enforced in OVS, because of this new
>> approach. The later recompute iterations would slow down the previous
>> computed OVS flow installation. In your test you used parallel 10, which
>> means at any point there might be new changes from one client such as
>> creating new router that triggers recomputing, which can block the OVS flow
>> installation triggered earlier for another client. So overall you will see
>> much bigger latency for each individual test iteration.
>>
>> This can also explain why I didn't reproduce the problem in my
>> single-client single-node environment, since each iteration is serialized.
>>
>> [1]
>> https://github.com/openvswitch/ovs/commit/74c760c8fe99d554b94423d49d13d5ca3dea0d9e
>>
>> To prove this theory, could you help with two tests reusing your
>> environment? Thanks a lot!
>>
>>
> Thanks Han. I will try these and come back to you with the results.
>
> Numan
>
>
>> 1. Instead of parallelism of 10, try 1, to make sure the test is
>> serialized. I'd expect the result should be similar w/ v.s. w/o I-P.
>>
>> 2. Try below patch on the I-P version you are testing, to see if the
>> problem is gone.
>> ----8><--------------------------------------------><8---------------
>> diff --git a/ovn/controller/ofctrl.c b/ovn/controller/ofctrl.c
>> index 043abd6..0fcaa72 100644
>> --- a/ovn/controller/ofctrl.c
>> +++ b/ovn/controller/ofctrl.c
>> @@ -985,7 +985,7 @@ add_meter(struct ovn_extend_table_info *m_desired,
>>   * in the correct state and not backlogged with existing flow_mods.  (Our
>>   * criteria for being backlogged appear very conservative, but the socket
>>   * between ovn-controller and OVS provides some buffering.) */
>> -static bool
>> +bool
>>  ofctrl_can_put(void)
>>  {
>>      if (state != S_UPDATE_FLOWS
>> diff --git a/ovn/controller/ofctrl.h b/ovn/controller/ofctrl.h
>> index ed8918a..2b21c11 100644
>> --- a/ovn/controller/ofctrl.h
>> +++ b/ovn/controller/ofctrl.h
>> @@ -51,6 +51,7 @@ void ofctrl_put(struct ovn_desired_flow_table *,
>>                  const struct sbrec_meter_table *,
>>                  int64_t nb_cfg,
>>                  bool flow_changed);
>> +bool ofctrl_can_put(void);
>>  void ofctrl_wait(void);
>>  void ofctrl_destroy(void);
>>  int64_t ofctrl_get_cur_cfg(void);
>> diff --git a/ovn/controller/ovn-controller.c
>> b/ovn/controller/ovn-controller.c
>> index c4883aa..c85c6fa 100644
>> --- a/ovn/controller/ovn-controller.c
>> +++ b/ovn/controller/ovn-controller.c
>> @@ -1954,7 +1954,7 @@ main(int argc, char *argv[])
>>
>>                      stopwatch_start(CONTROLLER_LOOP_STOPWATCH_NAME,
>>                                      time_msec());
>> -                    if (ovnsb_idl_txn) {
>> +                    if (ovnsb_idl_txn && ofctrl_can_put()) {
>>                          engine_run(&en_flow_output, ++engine_run_id);
>>                      }
>>                      stopwatch_stop(CONTROLLER_LOOP_STOPWATCH_NAME,
>>
>

Hi Han,

So far I could do just one run after applying your above suggested patch
with the I-P version and  results look promising.
It seems to me the problem is gone.

+--------------------------------------------------------------------------------------------------------------------------+
|                                             Response Times (sec)
                                                          |
+----------------------------------+--------+----------+----------+----------+---------+---------+------------+-------+
| action                                | min   | median | 90%ile | 95%ile
| max    | avg    | success | count   |
+----------------------------------+--------+----------+----------+----------+---------+---------+------------+-------+
| ovn_network.ping_ports   | 0.037 | 10.236 | 10.392 | 10.462 | 20.455 |
7.15   | 100.0%  | 1000  |
+----------------------------------+--------+----------+----------+----------+---------+---------+------------+-------+
| ovn_network.ping_ports   | 0.036 | 10.255 | 10.448 | 11.323 | 20.791 |
7.83   | 100.0%  | 1000  |
+----------------------------------+--------+----------+----------+----------+---------+---------+------------+-------+

The first row represents Non IP and the 2nd row represents IP + your
suggested patch.
The values are comparable and lot better compared to without your patch.

On monday I will do more runs to be sure that the data is consistent and
get back to you.

If the results are consistent, I would try to run the tests which Daniel
and Lucas ran on an openstack deployment.

Thanks
Numan
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