[dpdk-dev] [EXT] Re: [PATCH v4 1/4] ethdev: add tm support for shaper config in pkt mode

[Ferruh Yigit]

On 5/1/2020 2:16 PM, Nithin Dabilpuram wrote:
> On Fri, May 01, 2020 at 11:27:02AM +0100, Ferruh Yigit wrote:
>> External Email
>>
>> ----------------------------------------------------------------------
>> On 4/29/2020 10:03 AM, Bruce Richardson wrote:
>>> On Wed, Apr 29, 2020 at 09:45:44AM +0100, Dumitrescu, Cristian wrote:
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: Thomas Monjalon <thomas at monjalon.net>
>>>>> Sent: Tuesday, April 28, 2020 4:54 PM
>>>>> To: Jerin Jacob <jerinjacobk at gmail.com>; Dumitrescu, Cristian
>>>>> <cristian.dumitrescu at intel.com>
>>>>> Cc: Richardson, Bruce <bruce.richardson at intel.com>; Yigit, Ferruh
>>>>> <ferruh.yigit at intel.com>; Luca Boccassi <bluca at debian.org>; Nithin
>>>>> Dabilpuram <nithind1988 at gmail.com>; Singh, Jasvinder
>>>>> <jasvinder.singh at intel.com>; Andrew Rybchenko
>>>>> <arybchenko at solarflare.com>; dev at dpdk.org; jerinj at marvell.com;
>>>>> kkanas at marvell.com; Nithin Dabilpuram <ndabilpuram at marvell.com>;
>>>>> Kinsella, Ray <ray.kinsella at intel.com>; Neil Horman
>>>>> <nhorman at tuxdriver.com>; Kevin Traynor <ktraynor at redhat.com>; David
>>>>> Marchand <david.marchand at redhat.com>
>>>>> Subject: Re: [dpdk-dev] [PATCH v4 1/4] ethdev: add tm support for shaper
>>>>> config in pkt mode
>>>>>
>>>>> 28/04/2020 17:04, Luca Boccassi:
>>>>>> On Tue, 2020-04-28 at 15:45 +0100, Bruce Richardson wrote:
>>>>>>> On Tue, Apr 28, 2020 at 03:06:20PM +0100, Ferruh Yigit wrote:
>>>>>>>> On 4/27/2020 5:59 PM, Jerin Jacob wrote:
>>>>>>>>> On Mon, Apr 27, 2020 at 10:19 PM Ferruh Yigit
>>>>> <ferruh.yigit at intel.com> wrote:
>>>>>>>>>> On 4/27/2020 5:29 PM, Jerin Jacob wrote:
>>>>>>>>>>> On Mon, Apr 27, 2020 at 9:42 PM Ferruh Yigit
>>>>> <ferruh.yigit at intel.com> wrote:
>>>>>>>>>>>> On 4/27/2020 10:19 AM, Dumitrescu, Cristian wrote:
>>>>>>>>>>>>> From: Yigit, Ferruh <ferruh.yigit at intel.com>
>>>>>>>>>>>>>> On 4/24/2020 11:28 AM, Dumitrescu, Cristian wrote:
>>>>>>>>>>>>>>> From: Nithin Dabilpuram <nithind1988 at gmail.com>
>>>>>>>>>>>>>>>> This patch also updates tm port/level/node capability
>>>>> structures with
>>>>>>>>>>>>>>>> exiting features of scheduler wfq packet mode,
>>>>> scheduler wfq byte mode
>>>>>>>>>>>>>>>> and private/shared shaper byte mode.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> SoftNIC PMD is also updated with new capabilities.
>>>>> [...]
>>>>>>>>>>>>>> Hi Nithin,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> It looks like patch is causing ABI break, I am getting following
>>>>> warning [1],
>>>>>>>>>>>>>> can you please check?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__pastebin.com_XYNFg14u&d=DwIDaQ&c=nKjWec2b6R0mOyPaz7xtfQ&r=FZ_tPCbgFOh18zwRPO9H0yDx8VW38vuapifdDfc8SFQ&m=ej5sP3-cEhEoCTZOia-QivXqgljtzBcMLtZGs-5c-Uc&s=B8z_5mQ2xO3C1izjmRe2zBApMrCUcW6KcAN-adglhJQ&e= 
>>>>>>>>>>>>>
>>>>>>>>>>>>> Hi Ferruh,
>>>>>>>>>>>>>
>>>>>>>>>>>>> The RTE_TM API is marked as experimental,
>>>>>>>>>>>>> but it looks that this was not correctly marked
>>>>>>>>>>>>> when __rte_experimental ABI checker was introduced.
>>>>>>>>>>>>>
>>>>>>>>>>>>> It is marked as experimental at the top of the rte_tm.h,
>>>>>>>>>>>>> similarly to other APIs introduced around same time,
>>>>>>>>>>>>> but it was not correctly picked up by the ABI check procedure
>>>>>>>>>>>>> when later introduced, so __rte_experimental was not added
>>>>> to every function.
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> :(
>>>>>>>>>>>>
>>>>>>>>>>>> Is it time to mature them?
>>>>>>>>>>>>
>>>>>>>>>>>> As you said they are not marked as experimental both in header
>>>>> file (function
>>>>>>>>>>>> declarations) and .map file.
>>>>>>>>>>>>
>>>>>>>>>>>> The problem is, they are not marked as experimental in
>>>>> DPDK_20.0 ABI (v19.11),
>>>>>>>>>>>> so marking them as experimental now will break the ABI. Not
>>>>> sure what to do,
>>>>>>>>>>>> cc'ed a few ABI related names for comment.
>>>>>>>>>>>>
>>>>>>>>>>>> For me, we need to proceed as the experimental tag removed
>>>>> and APIs become
>>>>>>>>>>>> mature starting from v19.11, since this is what happened in
>>>>> practice, and remove
>>>>>>>>>>>> a few existing being experimental references in the doxygen
>>>>> comments.
>>>>>>>>>>>
>>>>>>>>>>> I think, accidentally we can not make a library as NON-
>>>>> experimental.
>>>>>>>>>>> TM never went through experimental to mature transition(see git
>>>>> log
>>>>>>>>>>> lib/librte_ethdev/rte_tm.h)
>>>>>>>>>>> It was a bug to not mark as experimental in each function in the
>>>>> ABI process.
>>>>>>>>>>> Some of the features like packet marking are not even
>>>>> implemented by any HW.
>>>>>>>>>>> I think, we can make API stable only all the features are
>>>>> implemented
>>>>>>>>>>> by one or two HW.
>>>>>
>>>>> Yes this is what was decided one or two years ago I think.
>>>>> But rte_tm API was introduced 3 years ago and is implemented by 6 PMDs.
>>>>>
>>>>>
>>>>>
>>>>>>>>>> Fair enough, specially if the API is not ready yet.
>>>>>>>>>>
>>>>>>>>>> But they were part of stable ABI, and marking them as experimental
>>>>> now will
>>>>>>>>>> break the old applications using these APIs.
>>>>>>>>>
>>>>>>>>> it is still marked as EXPERIMENTAL everywhere and API is not ready
>>>>> yet.
>>>>>
>>>>> rte_tm is implemented in 6 PMDs.
>>>>>
>>>>>
>>>>>>>> Existing experimental marks are text only for human parsing.
>>>>>>>>
>>>>>>>> The compiler attribute and build time checks are missing, and the
>>>>> symbol in the
>>>>>>>> binary doesn't have experimental tag. Our scripts and automated
>>>>> checks won't
>>>>>>>> detect it as experimental.
>>>>>>>>
>>>>>>>> My point is just having experimental comment in header file is not
>>>>> enough to
>>>>>>>> qualify the APIs as experimental.
>>>>>>>>
>>>>>>>>> Anyway, we need to break the ABI to make it work on various HW.
>>>>>
>>>>> Yes this is why I was asking in 19.11 to check our API,
>>>>> in order to avoid such situation.
>>>>>
>>>>>
>>>>>>>>> I am not sure what to do?
>>>>>
>>>>> Either manage ABI versioning, or wait 20.11.
>>>>>
>>>>>
>>>>>>>>> IMO, We need to send a patch as Fixes: for the bug of not adding
>>>>>>>>> __rte_experimental in each function.
>>>>>
>>>>> No, this is wrong.
>>>>>
>>>>
>>>> Why exactly is this wrong? This is the gap that caused the current discussion, right?
>>>>
>>> It's wrong for this release, since we can't change things from stable back
>>> to experimental. Any such patch will have to wait for 20.11, as agreed in
>>> the discussion.
>>>
>>
>> Deferring the patchet for this release.
>>
>> Reminder that if the option "to mark rte_tm_* as experimental in v20.11"
>> selected, requires deprecation notice before v20.11.
> 
> Thanks Ferruh for reminder. I'll send a deprecation notice patch for the same.
> 

Hi Nithin Kumar, Cristian, Jerin,

Who is working on updating APIs as experimental? We need that patch to proceed
with this one.