On 6/20/23 21:01, Han Zhou wrote:
> On Tue, Jun 20, 2023 at 12:48 AM Dumitru Ceara <[email protected]> wrote:
>>
>> On 6/20/23 03:49, Han Zhou wrote:
>>> On Tue, Jun 6, 2023 at 7:57 AM Dumitru Ceara <[email protected]> wrote:
>>>>
>>>> We don't need to explicitly add port bindings that were already bound
>>>> locally.  We implicitly get those because we monitor the datapaths
>>>> they're attached to.
>>>>
>>>> When performing an ovn-heater 500-node density-heavy scale test [0],
> with
>>>> conditional monitoring enabled, the unreasonably long poll intervals on
>>>> the Southbound database (the ones that took more than one second) are
>>>> measured as:
>>>>
>>>>   ---------------------------------------------------------------------
>>>>        Count      Min        Max       Median      Mean   95 percentile
>>>>   ---------------------------------------------------------------------
>>>>         56.0     1010.0     2664.0     1455.5     1544.9     2163.0
>>>>         77.0     1015.0     3460.0     1896.0     1858.2     2907.8
>>>>         69.0     1010.0     3118.0     1618.0     1688.1     2582.4
>>>>   ---------------------------------------------------------------------
>>>>        202.0     1010.0     3460.0     1610.0     1713.3     2711.5
>>>>
>>>> Compared to the baseline results (also with conditional monitoring
>>>> enabled):
>>>>   ---------------------------------------------------------------------
>>>>        Count      Min        Max       Median      Mean   95 percentile
>>>>   ---------------------------------------------------------------------
>>>>        141.0     1003.0    18338.0     1721.0     2625.4     7626.0
>>>>        151.0     1019.0    80297.0     1808.0     3410.7     9089.0
>>>>        165.0     1007.0    50736.0     2354.0     3067.7     7309.8
>>>>   ---------------------------------------------------------------------
>>>>        457.0     1003.0    80297.0     2131.0     3044.6     7799.6
>>>>
>>>> We see significant improvement on the server side.  This is explained
>>>> by the fact that now the Southbound database server doesn't need to
>>>> apply as many conditions as before when filtering individual monitor
>>>> contents.
>>>>
>>> Thanks Dumitru for the great improvement! This is very helpful for the
> high
>>> port-density environment.
>>> Just to make sure I understand the test result correctly, in [0], it
> shows
>>> 22500 pods and 500 nodes, so is it 45 pods per node?
>>>
>>
>> Yes, for density-heavy tests (load balancers are also configured) the
>> pod density is 45 per node.
>>
>>>> Note: Sub-ports - OVN switch ports with parent_port set - have to be
>>>> monitored unconditionally as we cannot efficiently determine their
> local
>>>> datapaths without including all local OVS interfaces in the monitor.
>>>> This, however, should not be a huge issue because the majority of ports
>>>> are regular VIFs, not sub-ports.
>>>
>>> I am not sure if we can make such a conclusion. For the current ovn-k8s
> or
>>> environments similar to that, it shouldn't be a problem.
>>> However, for environments that model pods/containers as sub-ports of
> the VM
>>> VIFs, probably most of the majority of the ports would be sub-ports.
> This
>>> is what sub-ports are designed for, right?
>>
>> My impression was that this was one of the use cases for OpenStack and
>> that it's only one of the different ways of providing container
>> connectivity in a given deployment.  But I might be wrong.  I can remove
>> this sentence, it makes a lot of assumptions indeed.
>>
>>> So, I think this would be a significant change of data monitored for
> those
>>> environments. I'd suggest at least we should properly document the
>>> implication in the documents (such as ovn-monitor-all, and also the
>>> sub-port related parts). There may also be such users who prefer not
>>> monitoring all sub-ports (for efficiency of ovn-controller) sacrificing
> SB
>>> DB performance (probably they don't have very high port density so the
>>> conditional monitoring impact is not that big). I am not aware of any
> such
>>> users yet, but if they complain, we will have to provide a knob, if no
>>> better ideas.
>>>
>>
>> I agree, if really needed, we can easily add a knob.
>>
>> What do you think of the following incremental?  I can fold it in if it
>> looks good to you.
> 
> Thanks Dumitru. The below documentation looks good. In addition, I think we
> should add some notes in the ovn-nb.xml under the section <group
> title="Containers"> of Logical_Switch_Port, which is the place where the
> "sub-port" feature is described. Could you add it as well?
> 

To avoid an "incremental on top of another incremental" I posted v2.  I
also added a NEWS item as this is a user-visible change.

Please let me know what you think.

https://patchwork.ozlabs.org/project/ovn/patch/[email protected]/

Thanks,
Dumitru

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