Re: [dpdk-stable] [dpdk-dev] 19.11.4 patches review and test

[Ilya Maximets <i.maximets@ovn.org>]

On 3/23/21 7:17 PM, Thomas Monjalon wrote:
> 22/03/2021 15:27, Christian Ehrhardt:
>> On Mon, Mar 22, 2021 at 1:25 PM Thomas Monjalon <thomas@monjalon.net> wrote:
>>> 22/03/2021 12:59, Luca Boccassi:
>>>> On Mon, 2021-03-22 at 11:41 +0000, Bruce Richardson wrote:
>>>>> On Mon, Mar 22, 2021 at 10:49:54AM +0100, Christian Ehrhardt wrote:
>>>>>> On Thu, Mar 18, 2021 at 7:25 PM Pai G, Sunil <sunil.pai.g@intel.com> wrote:
>>>>>>> Hi Christian, Ilya
>>>>>>> From: Ilya Maximets <i.maximets@ovn.org>
>>>>>>>> On 3/18/21 2:36 PM, Pai G, Sunil wrote:
>>>>>>>>> Hey Christian,
>>>>>>>>>
>>>>>>>>> <snipped>
>>>>>>>>>
>>>>>>>>>> back  in 19.11.4 these DPDK changes were not picked up as they have
>>>>>>>>>> broken builds as discussed here.
>>>>>>>>>> Later on the communication was that all this works fine now and
>>>>>>>>>> thereby Luca has "reverted the reverts" in 19.11.6 [1].
>>>>>>>>>>
>>>>>>>>>> But today we were made aware that still no OVS 2.13 builds against a
>>>>>>>>>> DPDK that has those changes.
>>>>>>>>>> Not 2.13.1 as we have it in Ubuntu nor (if it needs some OVS changes
>>>>>>>>>> backported) the recent 2.13.3 does build.
>>>>>>>>>> They still fail with the very same issue I reported [2] back then.
>>>>>>>>>>
>>>>>>>>>> Unfortunately I have just released 19.11.7 so I can't revert them
>>>>>>>>>> there - but OTOH reverting and counter reverting every other release
>>>>>>>>>> seems wrong anyway.
>>>>>>>>
>>>>>>>> It is wrong indeed, but the main question here is why these patches was
>>>>>>>> backported to stable release in a first place?
>>>>>>>>
>>>>>>>> Looking at these patches, they are not actual bug fixes but more like "nice to
>>>>>>>> have" features that additionally breaks the way application links with DPDK.
>>>>>>>> Stuff like that should not be acceptable to the stable release without a strong
>>>>>>>> justification or, at least, testing with actual applications.
>>>>>>
>>>>>> I agree, but TBH IIRC these changes were initially by OVS people :-)
>>>>>> One could chase down the old talks between Luca and the requesters, but I don't
>>>>>> think that gains us that much.
>>>>>>
>>>>>>>> Since we already have a revert of revert, revert of revert of revert doesn't
>>>>>>>> seem so bad.
>>>>>>
>>>>>> As long as we don't extend this series, yeah
>>>>>>
>>>>>>>>>> I wanted to ask if there is a set of patches that OVS would need to
>>>>>>>>>> backport to 2.13.x to make this work?
>>>>>>>>>> If they could be identified and prepared Distros could use them on
>>>>>>>>>> 2.13.3 asap and 2.13.4 could officially release them for OVS later on.
>>>>>>>>>>
>>>>>>>>>> But for that we'd need a hint which OVS changes that would need to be.
>>>>>>>>>> All I know atm is from the testing reports on DPDK it seems that OVS
>>>>>>>>>> 2.14.3 and 2.15 are happy with the new DPDK code.
>>>>>>>>>> Do you have pointers on what 2.13.3 would need to get backported to
>>>>>>>>>> work again in regard to this build issue.
>>>>>>>>>
>>>>>>>>> You would need to use partial contents from patch :
>>>>>>>>> http://patchwork.ozlabs.org/project/openvswitch/patch/1608142365-
>>>>>>>> 26215
>>>>>>>>> -1-git-send-email-ian.stokes@intel.com/
>>>>>>>>>
>>>>>>>>> If you'd like me to send patches which would work with 2.13, 2.14, I'm
>>>>>>>>> ok with that too.[keeping only those parts from patch which fixes the issue
>>>>>>>> you see.] But we must ensure it doesn’t cause problems for OVS too.
>>>>>>>>> Your thoughts Ilya ?
>>>>>>>>
>>>>>>>> We had more fixes on top of this particular patch and I'd like to not cherry-
>>>>>>>> pick and re-check all of this again.
>>>>>>>
>>>>>>> I agree, we had more fixes on top of this. It would be risky to cherry-pick.
>>>>>>> So it might be a better option to revert.
>>>>>>
>>>>>> I agree, as far as I assessed the situation it would mean the revert
>>>>>> of the following list.
>>>>>> And since that is a lot of "reverts" in the string, to be clear it means that
>>>>>> those original changes would not be present anymore in 19.11.x.
>>>>>>
>>>>>> f49248a990 Revert "Revert "build/pkg-config: prevent overlinking""
>>>>>> 39586a4cf0 Revert "Revert "build/pkg-config: improve static linking flags""
>>>>>> 906e935a1f Revert "Revert "build/pkg-config: output drivers first for
>>>>>> static build""
>>>>>> deebf95239 Revert "Revert "build/pkg-config: move pkg-config file creation""
>>>>>> a3bd9a34bf Revert "Revert "build: always link whole DPDK static libraries""
>>>>>> d4bc124438 Revert "Revert "devtools: test static linkage with pkg-config""
>>>>>>
>>>>>> But to avoid going back&forth I'd prefer to have a signed-off on that
>>>>>> approach from:
>>>>>> - Luca (for 19.11.6 which has added the changes)
>>>>>> - Bruce (for being involved in the old&new case in general)
>>>>>> - Thomas (for general master maintainer thoughts)
>>>>>>
>>>>>
>>>>> If this is what is needed to ensure OVS can continue to use this release
>>>>> series, then I am absolutely fine with it.
>>>>
>>>> This was requested by OVS, so if they don't need it anymore it's fine
>>>> by me as well
>>>
>>> I am not sure to understand the full story,
>>> but I am a bit worried that our release is dictated by
>>> a single "user" (project using DPDK).
>>
>> Sure, fair to ask for more detail :-)
>>
>>> Please do you have links of discussion history?
>>
>> I ordered the events by time and added links to those occasions that I
>> could find:
>>
>> July 2020            - Initial request by OVS - *1
>> July 2020            - Initial queuing     -
>> http://mails.dpdk.org/archives/stable/2020-July/024248.html
>> September 2020 - Issues identified; changes reverted    -
>> http://mails.dpdk.org/archives/stable/2020-September/024796.html
>> October 2020      - Re-applying early in 19.11.6 cycle    - *1
>> November 2020  - Tests didn't spot it with 19.11.6 as OVS 2.14.x (not
>> the 2.13 LTS) was tested    -
>> https://doc.dpdk.org/guides-19.11/rel_notes/release_19_11.html#id16
>> March 2021         - Same issue re-found in >=19.11.6    -
>> http://mails.dpdk.org/archives/stable/2021-March/029418.html
>>
>> *1 - Luca and I looked for logs, there are no links that I'd know of
>> and Luca said it might have come up as a request during a meeting.
> 
> First, I agree to revert the changes again if it causes a regression.
> Second, do we know the root cause of the issue?
> Is it a problem with the version of pkg-config?
> Is it OK with DPDK 20.11?
> 

I'd like to also ask someone to test build of both OVS 2.13 and OVS 2.14
with these changes and with these changes reverted. 

Sunil, could you do that?

> About the process, I see multiple issues:
> 
> 1/ Some patches were backported for OVS only,
> but it could break other applications.
> 
> 2/ It is not clear whether the patches were really needed in 19.11.
> 
> 3/ There is no trace of backport requests in the mailing list.
> 
> So I feel we should be stricter on the reasons for a backport.
> Note: I am not blaming anyone. Everybody tries to do the best.
> I believe sharing requests and discussions on the mailing list
> could help in the decision process.

+1

> 
> Thanks for all the work.