On 9/1/25 4:17 PM, Dumitru Ceara wrote:
> On 9/1/25 4:12 PM, Ilya Maximets wrote:
>> On 9/1/25 3:33 PM, Dumitru Ceara wrote:
>>> Hi Ilya,
>>>
>>> Thanks for the review!
>>>
>>> On 9/1/25 3:23 PM, Ilya Maximets wrote:
>>>> On 9/1/25 1:22 PM, Dumitru Ceara wrote:
>>>>> Since 6919992d8781 ("Datapath_Binding: Separate type column and sync
>>>>> NB.UUID to SB."), a new type column is added to SB datapaths to
>>>>> differentiate between datapath types (switch vs router). The same
>>>>> commit also changed northd such that newly created SB datapaths have as
>>>>> UUID the same value as the NB switch/router UUID. All SB.Datapath
>>>>> records were also updated and their 'type' field populated
>>>>>
>>>>> It also added a helper function, datapath_get_nb_uuid_and_type(), to
>>>>> abstract out the extraction of a SB datapath's corresponding NB UUID and
>>>>> type in the following way:
>>>>> - if the SB.Datapath.type field has a value, the helper assumed that the
>>>>> SB.Datapath.UUID is equal to the NB.Logical_Switch/Router.UUID so it
>>>>> returned the 'type' value and the SB UUID
>>>>> - else (for "old style") datapaths it extracted the NB UUID and type
>>>>> from the SB.Datapath.external_ids (as used to be done before the
>>>>> commit).
>>>>>
>>>>> This creates an upgrade issue thoughi: older (already existing before
>>>>> upgrade) SB datapaths are not immediately recreated and their 'type'
>>>>> is set; so the NB UUID value returned by datapath_get_nb_uuid_and_type()
>>>>> for these records is incorrect.
>>>>>
>>>>> That stays like that until datapaths are finally recreated (due to other
>>>>> events, e.g., full recompute of the datapath-sync nodes). All that time
>>>>> the lflow manager will incorrectly determine that the existing lflows
>>>>> that are stale. That's because the lflow manager uses
>>>>> ovn_datapath_from_sbrec() which in turn relied on
>>>>> datapath_get_nb_uuid_and_type() to determine the in-memory ovn_datapath
>>>>> corresponding to the logical flow.
>>>>>
>>>>> There's no need to avoid re-creating SB.Datapath bindings as soon as
>>>>> ovn-northd determines that they're not using the new scheme. In order
>>>>> to achieve that we add two sets of helpers:
>>>>> a. one to be used by ovn-northd, ovn_datapath_get_nb_uuid_and_type()
>>>>> which only parses the new type of datapaths (everything else, i.e.
>>>>> old-style datapaths, will be considered stale)
>>>>> b. one to be used by all other readers of SB datapaths (e.g.,
>>>>> ovn-controller, ovn-ic), datapath_get_nb_uuid_and_type_legacy()
>>>>> which relies on parsing external IDs (even in the new type of
>>>>> datapaths external IDs are still populated with the NB UUID in order
>>>>> to maintain backwards compatibility).
>>>>
>>>> Can we ever switch all users to the non-leagacy? I'm not sure...
>>>> Should probably be a TODO entry for this.
>>>>
>>>
>>> We can, it should happen in the next LTS (26.03) though. And it should
>>> be the plan.
>>
>> How the transition is done? i.e. is that guaranteed that the database
>> is fully translated to the new format after the next upgrade? Or was it
>> decided that the full database rewrite on upgrade is not an issue and it
>> works this way?
>>
>
> Yes, it's guaranteed that after upgrade to 25.09.0 (or more recent) the
> database is fully translated. It was decided that it's not a concern to
> do that. Discussed here:
>
> https://mail.openvswitch.org/pipermail/ovs-dev/2025-August/425327.html
>
>>> Good point about adding a TODO. I can post a v3 or if
>>> this is the only change that needs to happen maybe whoever merges this
>>> series can add the following incremental:
>>>
>>> diff --git a/TODO.rst b/TODO.rst
>>> index a9fe3ec4e8..4c7aa0c772 100644
>>> --- a/TODO.rst
>>> +++ b/TODO.rst
>>> @@ -99,6 +99,12 @@ OVN To-do List
>>> * Implement I-P for datapath groups.
>>> * Implement I-P for route exchange relevant ports.
>>>
>>> +* ovn-northd Incremental processing
>>> +
>>> + * Remove datapath_get_nb_uuid_and_type_legacy() in the next LTS (26.03)
>>> as
On second thought, this should be "after the next LTS (in 26.09)".
>>> + all deployments should be using the new SB.Datapath_Binding.type column
>>> + at that point.
>>> +
>>> * ovn-northd parallel logical flow processing
>>>
>>> * Multi-threaded logical flow computation was optimized for the case
>>> ---
>>>
>>>> If not, then we should just drop the "new" way and stop duplicating
>>>> the same information in two places.
>>>>
>>>> Best regards, Ilya Maximets.
>>>>
>>>
>>> Regards,
>>> Dumitru
>>>
>>
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