On 28/04/2020 15:45, 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.yi...@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.yi...@intel.com>
>>>>> wrote:
>>>>>>
>>>>>> On 4/27/2020 10:19 AM, Dumitrescu, Cristian wrote:
>>>>>>>
>>>>>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: Yigit, Ferruh <ferruh.yi...@intel.com>
>>>>>>>> Sent: Saturday, April 25, 2020 9:09 PM
>>>>>>>> To: Dumitrescu, Cristian <cristian.dumitre...@intel.com>; Nithin
>>>>>>>> Dabilpuram
>>>>>>>> <nithind1...@gmail.com>; Singh, Jasvinder <jasvinder.si...@intel.com>;
>>>>>>>> Thomas Monjalon <tho...@monjalon.net>; Andrew Rybchenko
>>>>>>>> <arybche...@solarflare.com>
>>>>>>>> Cc: dev@dpdk.org; jer...@marvell.com; kka...@marvell.com; Nithin
>>>>>>>> Dabilpuram <ndabilpu...@marvell.com>
>>>>>>>> Subject: Re: [PATCH v4 1/4] ethdev: add tm support for shaper config
>>>>>>>> in pkt
>>>>>>>> mode
>>>>>>>>
>>>>>>>> On 4/24/2020 11:28 AM, Dumitrescu, Cristian wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> -----Original Message-----
>>>>>>>>>> From: Nithin Dabilpuram <nithind1...@gmail.com>
>>>>>>>>>> Sent: Wednesday, April 22, 2020 6:21 PM
>>>>>>>>>> To: Singh, Jasvinder <jasvinder.si...@intel.com>; Dumitrescu,
>>>>>>>>>> Cristian
>>>>>>>>>> <cristian.dumitre...@intel.com>; Thomas Monjalon
>>>>>>>>>> <tho...@monjalon.net>; Yigit, Ferruh <ferruh.yi...@intel.com>; Andrew
>>>>>>>>>> Rybchenko <arybche...@solarflare.com>
>>>>>>>>>> Cc: dev@dpdk.org; jer...@marvell.com; kka...@marvell.com; Nithin
>>>>>>>>>> Dabilpuram <ndabilpu...@marvell.com>
>>>>>>>>>> Subject: [PATCH v4 1/4] ethdev: add tm support for shaper config in
>>>>>>>>>> pkt
>>>>>>>>>> mode
>>>>>>>>>>
>>>>>>>>>> From: Nithin Dabilpuram <ndabilpu...@marvell.com>
>>>>>>>>>>
>>>>>>>>>> Some NIC hardware support shaper to work in packet mode i.e
>>>>>>>>>> shaping or ratelimiting traffic is in packets per second (PPS) as
>>>>>>>>>> opposed to default bytes per second (BPS). Hence this patch
>>>>>>>>>> adds support to configure shared or private shaper in packet mode,
>>>>>>>>>> provide rate in PPS and add related tm capabilities in
>>>>>>>>>> port/level/node
>>>>>>>>>> capability structures.
>>>>>>>>>>
>>>>>>>>>> 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.
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: Nithin Dabilpuram <ndabilpu...@marvell.com>
>>>>>>>>>> ---
>>>>>>>>>> v3..v4:
>>>>>>>>>> - Update text under packet_mode as per Cristian.
>>>>>>>>>> - Update rte_eth_softnic_tm.c based on Jasvinder's comments.
>>>>>>>>>> - Add error enum
>>>>>>>> RTE_TM_ERROR_TYPE_SHAPER_PROFILE_PACKET_MODE
>>>>>>>>>> - Fix shaper_profile_check() with packet mode check
>>>>>>>>>> - Fix typo's
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Acked-by: Cristian Dumitrescu <cristian.dumitre...@intel.com>
>>>>>>>>>
>>>>>>>>
>>>>>>>> Hi Nithin,
>>>>>>>>
>>>>>>>> It looks like patch is causing ABI break, I am getting following
>>>>>>>> warning [1],
>>>>>>>> can you please check?
>>>>>>>>
>>>>>>>> [1]
>>>>>>>> https://pastebin.com/XYNFg14u
>>>>>>>
>>>>>>>
>>>>>>> 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.
>>>>
>>>> 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.
>>
>> 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.
>>> I am not sure what to do?
>>> IMO, We need to send a patch as Fixes: for the bug of not adding
>>> __rte_experimental in each function.
>>
>> Yes, this is where we are, both you and Cristian suggest API is not ready and
>> should be experimental, but they were part of stable ABI, making them
>> experimental will break the ABI.
>> It looks like there is no good option but we should select one of the bad
>> ones.
>>
>>>
>>> Traffic Management API - EXPERIMENTAL
>>> M: Cristian Dumitrescu <cristian.dumitre...@intel.com>
>>> T: git://dpdk.org/next/dpdk-next-qos
>>> F: lib/librte_ethdev/rte_tm*
>>>>
>>>>>
>>>>>>
>>>>>> Ray, Neil, David, Luca, Kevin, what do you think?
>>>>
> While I'm not called any of those names, allow me to give my 2c.
>
> Since these are marked in binaries as part of the stable ABI, I think we
> need to honour that for the next two releases 20.05 and 20.08 [which means
> that we need to put in versioned functions for any changes, not that we
> can't change anything]
>
> For 20.11, I think these should then have one of two options taken:
> * have these "fixed" and ready to be marked as stable, and officially part
> of v21 ABI or
> * mark them as experimental properly, and look to have them as part of the
> v22 or subsequent ABI
>
> Given the comments here, I would tend towards the latter of the above two
> options, but that's really a decision for the maintainers.
>
> Remember, this is not the first bug we have encountered where we messed up
> some ABI versions in the 19.11 release, and, like the previous one with the
> screwed up version number, I think we need to honour the ABI committments
> made, especially since in this case it's only for a few more months till
> 20.11 development starts.
>
> /Bruce
>
So the rte_tm API has been "EXPERIMENTAL" for quiet a long time, as far back as
v17.11.
To the extent it predates the experimental infrastructure the community
developed
since then. TM added in 17.08, EXPERIMENTAL appears to have been added in 17.11.
That said, some form of stable TM API should have emerged by this point.
So I am not sure that EXPERIMENTAL status was 100% warranted.
As Bruce points out.
It is simpler to wait for the next ABI breakage window in August.
And mark them EXPERIMENTAL at that point.
Thanks,
Ray K
