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 <[email protected]> > > > > wrote: > > > > > On 4/27/2020 5:29 PM, Jerin Jacob wrote: > > > > > > On Mon, Apr 27, 2020 at 9:42 PM Ferruh Yigit > > > > > > <[email protected]> wrote: > > > > > > > On 4/27/2020 10:19 AM, Dumitrescu, Cristian wrote: > > > > > > > > From: Yigit, Ferruh <[email protected]> > > > > > > > > > On 4/24/2020 11:28 AM, Dumitrescu, Cristian wrote: > > > > > > > > > > From: Nithin Dabilpuram <[email protected]> > > > > > > > > > > > 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://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.
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. > > > 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 <[email protected]> > > > > 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 > > +1 > > If they are not ready now, they haven't been ready for the past 6 > months either, so staying not ready for 6 more is the lesser evil. This API is almost 3 years old (release 17.08). That's good to improve it but we must respect the ABI contract that we all agreed. Summary: 17.08: rte_tm is introduced. 17.11: rte_mtr is introduced as experimental, but rte_tm remains stable. 18.02: __rte_experimental tag is introduced (including for rte_mtr), but rte_tm remains untouched as it is in stable ABI. 19.11: stable ABI is frozen until 20.11 20.05: rte_tm improvement is blocked because of ABI breakage. It should remind everybody of reviewing the new API and policies, and maintaining the existing code appropriately.
