From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
"Chautru, Nicolas" <nicolas.chautru@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>,
"gakhil@marvell.com" <gakhil@marvell.com>,
"hemant.agrawal@nxp.com" <hemant.agrawal@nxp.com>,
"Vargas, Hernan" <hernan.vargas@intel.com>,
Tom Rix <trix@redhat.com>, "mdr@ashroe.eu" <mdr@ashroe.eu>,
"david.marchand@redhat.com" <david.marchand@redhat.com>,
"stephen@networkplumber.org" <stephen@networkplumber.org>
Subject: Re: [PATCH v1 00/10] baseband/acc200
Date: Wed, 14 Sep 2022 15:27:57 +0200 [thread overview]
Message-ID: <687a0f05-d6c1-a70d-fe41-c8bc186e44af@redhat.com> (raw)
In-Reply-To: <YyHU4oAAVgU6vQlX@bricha3-MOBL.ger.corp.intel.com>
On 9/14/22 15:19, Bruce Richardson wrote:
> On Wed, Sep 14, 2022 at 01:50:05PM +0200, Maxime Coquelin wrote:
>>
>>
>> On 9/14/22 12:35, Thomas Monjalon wrote:
>>> 06/09/2022 14:51, Tom Rix:
>>>> On 9/1/22 1:34 PM, Chautru, Nicolas wrote:
>>>>> From: Tom Rix <trix@redhat.com>
>>>>>> On 8/31/22 6:26 PM, Chautru, Nicolas wrote:
>>>>>>> From: Tom Rix <trix@redhat.com>
>>>>>>>> On 8/31/22 3:37 PM, Chautru, Nicolas wrote:
>>>>>>>>>>>>> Comparing ACC200 & ACC100 header files, I
>>>>>>>>>>>>> understand ACC200 is an evolution of the ACC10x
>>>>>>>>>>>>> family. The FEC bits are really close, ACC200 main
>>>>>>>>>>>>> addition seems to be FFT acceleration which could
>>>>>>>>>>>>> be handled in ACC10x driver based on device ID.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I think both drivers have to be merged in order to
>>>>>>>>>>>>> avoid code duplication. That's how other families
>>>>>>>>>>>>> of devices (e.g. i40e) are handled.
>>>>>>>>>>>> I haven't seen your reply on this point. Do you
>>>>>>>>>>>> confirm you are working on a single driver for ACC
>>>>>>>>>>>> family in order to avoid code duplication?
>>>>>>>>>>>>
>>>>>>>>>>> The implementation is based on distinct ACC100 and
>>>>>>>>>>> ACC200 drivers. The 2
>>>>>>>>>> devices are fundamentally different generation, processes
>>>>>>>>>> and IP.
>>>>>>>>>>> MountBryce is an eASIC device over PCIe while ACC200 is
>>>>>>>>>>> an integrated
>>>>>>>>>> accelerator on Xeon CPU.
>>>>>>>>>>> The actual implementation are not the same, underlying
>>>>>>>>>>> IP are all distinct
>>>>>>>>>> even if many of the descriptor format have similarities.
>>>>>>>>>>> The actual capabilities of the acceleration are
>>>>>>>>>>> different and/or new. The workaround and silicon
>>>>>>>>>>> errata are also different causing different
>>>>>>>>>> limitation and implementation in the driver (see the
>>>>>>>>>> serie with ongoing changes for ACC100 in parallel).
>>>>>>>>>>> This is fundamentally distinct from ACC101 which was a
>>>>>>>>>>> derivative product
>>>>>>>>>> from ACC100 and where it made sense to share
>>>>>>>>>> implementation
>>>>>> between
>>>>>>>>>> ACC100 and ACC101.
>>>>>>>>>>> So in a nutshell these 2 devices and drivers are 2
>>>>>>>>>>> different beasts and the
>>>>>>>>>> intention is to keep them intentionally separate as in
>>>>>>>>>> the serie.
>>>>>>>>>>> Let me know if unclear, thanks!
>>>>>>>>>> Nic,
>>>>>>>>>>
>>>>>>>>>> I used a similarity checker to compare acc100 and acc200
>>>>>>>>>>
>>>>>>>>>> https://dickgrune.com/Programs/similarity_tester/
>>>>>>>>>>
>>>>>>>>>> l=simum.log if [ -f $l ]; then rm $l fi
>>>>>>>>>>
>>>>>>>>>> sim_c -s -R -o$l -R -p -P -a .
>>>>>>>>>>
>>>>>>>>>> There results are
>>>>>>>>>>
>>>>>>>>>> ./acc200/acc200_pf_enum.h consists for 100 % of
>>>>>>>>>> ./acc100/acc100_pf_enum.h material
>>>>>>>>>> ./acc100/acc100_pf_enum.h consists for 98 % of
>>>>>>>>>> ./acc200/acc200_pf_enum.h material
>>>>>>>>>> ./acc100/rte_acc100_pmd.h consists for 98 % of
>>>>>>>>>> ./acc200/acc200_pmd.h material ./acc200/acc200_vf_enum.h
>>>>>>>>>> consists for 95 % of ./acc100/acc100_pf_enum.h material
>>>>>>>>>> ./acc200/acc200_pmd.h consists for 92 % of
>>>>>>>>>> ./acc100/rte_acc100_pmd.h material
>>>>>>>>>> ./acc200/rte_acc200_cfg.h consists for 92 % of
>>>>>>>>>> ./acc100/rte_acc100_cfg.h material
>>>>>>>>>> ./acc100/rte_acc100_pmd.c consists for 87 % of
>>>>>>>>>> ./acc200/rte_acc200_pmd.c material
>>>>>>>>>> ./acc100/acc100_vf_enum.h consists for 80 % of
>>>>>>>>>> ./acc200/acc200_pf_enum.h material
>>>>>>>>>> ./acc200/rte_acc200_pmd.c consists for 78 % of
>>>>>>>>>> ./acc100/rte_acc100_pmd.c material
>>>>>>>>>> ./acc100/rte_acc100_cfg.h consists for 75 % of
>>>>>>>>>> ./acc200/rte_acc200_cfg.h material
>>>>>>>>>>
>>>>>>>>>> Spot checking the first *pf_enum.h at 100%, these are the
>>>>>>>>>> devices' registers, they are the same.
>>>>>>>>>>
>>>>>>>>>> I raised this similarity issue with 100 vs 101.
>>>>>>>>>>
>>>>>>>>>> Having multiple copies is difficult to support and should
>>>>>>>>>> be avoided.
>>>>>>>>>>
>>>>>>>>>> For the end user, they should have to use only one
>>>>>>>>>> driver.
>>>>>>>>>>
>>>>>>>>> There are really different IP and do not have the same
>>>>>>>>> interface (PCIe/DDR vs
>>>>>>>> integrated) and there is big serie of changes which are
>>>>>>>> specific to ACC100 coming in parallel. Any workaround,
>>>>>>>> optimization would be
>>>>>> different.
>>>>>>>>> I agree that for the coming serie of integrated accelerator
>>>>>>>>> we will use a
>>>>>>>> unified driver approach but for that very case that would be
>>>>>>>> quite messy to artificially put them within the same PMD.
>>>>>>>>
>>>>>>>> How is the IP different when 100% of the registers are the
>>>>>>>> same ?
>>>>>>>>
>>>>>>> These are 2 different HW aspects. The base toplevel
>>>>>>> configuration registers
>>>>>> are kept similar on purpose but the underlying IP are totally
>>>>>> different design and implementation.
>>>>>>> Even the registers have differences but not visible here, the
>>>>>>> actual RDL file
>>>>>> would define more specifically these registers bitfields and
>>>>>> implementation including which ones are not implemented (but that
>>>>>> is proprietary information), and at bbdev level the interface is
>>>>>> not some much register based than processing based on data from
>>>>>> DMA.
>>>>>>> Basically even if there was a common driver, all these would be
>>>>>>> duplicated
>>>>>> and they are indeed different IP (including different vendors)..
>>>>>>> But I agree with the general intent and to have a common driver
>>>>>>> for the
>>>>>> integrated driver serie (ACC200, ACC300...) now that we are
>>>>>> moving away from PCIe/DDR lookaside acceleration and eASIC/FPGA
>>>>>> implementation (ACC100/AC101).
>>>>>>
>>>>>> Looking a little deeper, at how the driver is lays out some of
>>>>>> its bitfields and private data by reviewing the
>>>>>>
>>>>>> ./acc200/acc200_pmd.h consists for 92 % of
>>>>>> ./acc100/rte_acc100_pmd.h
>>>>>>
>>>>>> There are some minor changes to existing reserved bitfields. A
>>>>>> new structure for fft. The acc200_device, the private data for
>>>>>> the driver, is an exact copy of acc100_device.
>>>>>>
>>>>>> acc200_pmd.h is the superset and could be used with little
>>>>>> changes as a common acc_pmd.h. acc200 is doing everything the
>>>>>> acc100 did in a very similar if not exact way, adding the fft
>>>>>> feature.
>>>>>>
>>>>>> Can you point to some portion of this patchset that is so unique
>>>>>> that it could not be abstracted to an if-check or function and so
>>>>>> requiring this separate, nearly identical driver ?
>>>>>>
>>>>> You used a similarity checker really, there are actually way more
>>>>> relevent differences than what you imply here. With regards to the
>>>>> 2 pf_enum.h file, there are many registers that have same or
>>>>> similar names but have now different values being mapped hence you
>>>>> just cannot use one for the other. Saying that
>>>>> "./acc200/acc200_pmd.h consists for 92 % of
>>>>> ./acc100/rte_acc100_pmd.h" is just not correct and really
>>>>> irrelevant. Just do a diff side by side please and check, that
>>>>> should be extremely obvious, that metrics tells more about the
>>>>> similarity checker limitation than anything else. Even when using
>>>>> a common driver for ACC200/300 they will have distinct register
>>>>> enum files being auto-generated and coming from distinct RDL.
>>>>> Again just do a diff of these 2 files. I believe you will agree
>>>>> that is not relevant for these files to try to artificially merged
>>>>> these together.
>>>>>
>>>>> With regards to the pmd.h, some structure/defines are indeed common
>>>>> and could be moved to a common file (for instance turboencoder and
>>>>> LDPC encoder which are more vanilla and unlikely to change for
>>>>> future product unlike the decoders which have different feature set
>>>>> and behaviour; or some 3GPP constant that can be defined once). We
>>>>> can definitely change these to put together shared
>>>>> structures/defines, but not intending to try to artificially put
>>>>> things together with spaghetti code. We would like to keep 3
>>>>> parallel versions of these PMD for 3 different product lines which
>>>>> are indeed fundamentally different designs (including different
>>>>> workaround required as can be seen on the parallel ACC100 serie
>>>>> under review). - one version for FPGA implementation (support for
>>>>> N3000, N6000, ...) - one version for eASIC lookaside card
>>>>> implementation (ACC100, ACC101, ...) - one version for the
>>>>> integrated Xeon accelerators (ACC200, ACC300, ...)
>>>>
>>>> Some suggestions on refactoring,
>>>>
>>>> For the registers, have a common file.
>>>>
>>>> For the shared functionality, ex/ ldpc encoder, break these out to
>>>> its own shared file.
>>>>
>>>> The public interface, see my earlier comments on the documentation,
>>>> should be have the same interfaces and the few differences
>>>> highlighted.
>>>
>>> +1 to have common files, and all in a single directory
>>> drivers/baseband/acc100/
>>
>> Jus to be sure we are aligned, do you mean to have both drivers in the
>> same directory, which will share some common files? That's the way I
>> would go.
>>
>
> I think the expectation is that the two drivers will diverge in future, so
> having separate directories should be ok, even with common files placed in
> one directory are shared with another. With meson include paths its pretty
> trivial to manage if it's just header files, and even if there are common C
> files, there is always the option of using drivers/common if we want to
> split them out. As I understand it, right now it's only headers inluding
> functions which can be static inline, so simple sharing via include paths
> should work fine.
Ok, then I prefer having the common parts in drivers/common/acc, in
order to make it clear changes to these common files have impact on
other drivers than ACC100.
Is that good for you?
Thanks,
Maxime
> /Bruce
>
next prev parent reply other threads:[~2022-09-14 13:28 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-08 0:01 Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 01/10] baseband/acc200: introduce PMD for ACC200 Nicolas Chautru
2022-09-12 1:08 ` [PATCH v2 00/11] baseband/acc200 Nic Chautru
2022-09-12 1:08 ` [PATCH v2 01/11] baseband/acc100: refactory to segregate common code Nic Chautru
2022-09-12 15:19 ` Bruce Richardson
2022-09-12 1:08 ` [PATCH v2 02/11] baseband/acc200: introduce PMD for ACC200 Nic Chautru
2022-09-12 15:41 ` Bruce Richardson
2022-09-12 1:08 ` [PATCH v2 03/11] baseband/acc200: add HW register definitions Nic Chautru
2022-09-12 1:08 ` [PATCH v2 04/11] baseband/acc200: add info get function Nic Chautru
2022-09-12 1:08 ` [PATCH v2 05/11] baseband/acc200: add queue configuration Nic Chautru
2022-09-12 1:08 ` [PATCH v2 06/11] baseband/acc200: add LDPC processing functions Nic Chautru
2022-09-12 1:08 ` [PATCH v2 07/11] baseband/acc200: add LTE " Nic Chautru
2022-09-12 1:08 ` [PATCH v2 08/11] baseband/acc200: add support for FFT operations Nic Chautru
2022-09-12 1:08 ` [PATCH v2 09/11] baseband/acc200: support interrupt Nic Chautru
2022-09-12 1:08 ` [PATCH v2 10/11] baseband/acc200: add device status and vf2pf comms Nic Chautru
2022-09-12 1:08 ` [PATCH v2 11/11] baseband/acc200: add PF configure companion function Nic Chautru
2022-07-08 0:01 ` [PATCH v1 02/10] baseband/acc200: add HW register definitions Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 03/10] baseband/acc200: add info get function Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 04/10] baseband/acc200: add queue configuration Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 05/10] baseband/acc200: add LDPC processing functions Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 06/10] baseband/acc200: add LTE " Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 07/10] baseband/acc200: add support for FFT operations Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 08/10] baseband/acc200: support interrupt Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 09/10] baseband/acc200: add device status and vf2pf comms Nicolas Chautru
2022-07-08 0:01 ` [PATCH v1 10/10] baseband/acc200: add PF configure companion function Nicolas Chautru
2022-07-12 13:48 ` [PATCH v1 00/10] baseband/acc200 Maxime Coquelin
2022-07-14 18:49 ` Vargas, Hernan
2022-07-17 13:08 ` Tom Rix
2022-07-22 18:29 ` Vargas, Hernan
2022-07-22 20:19 ` Tom Rix
2022-08-15 17:52 ` Chautru, Nicolas
2022-08-30 7:44 ` Maxime Coquelin
2022-08-30 19:45 ` Chautru, Nicolas
2022-08-31 16:43 ` Maxime Coquelin
2022-08-31 19:20 ` Thomas Monjalon
2022-08-31 19:26 ` Tom Rix
2022-08-31 22:37 ` Chautru, Nicolas
2022-09-01 0:28 ` Tom Rix
2022-09-01 1:26 ` Chautru, Nicolas
2022-09-01 13:49 ` Tom Rix
2022-09-01 20:34 ` Chautru, Nicolas
2022-09-06 12:51 ` Tom Rix
2022-09-14 10:35 ` Thomas Monjalon
2022-09-14 11:50 ` Maxime Coquelin
2022-09-14 13:19 ` Bruce Richardson
2022-09-14 13:27 ` Maxime Coquelin [this message]
2022-09-14 13:44 ` [EXT] " Akhil Goyal
2022-09-14 14:23 ` Thomas Monjalon
2022-09-14 19:57 ` Chautru, Nicolas
2022-09-14 20:08 ` Maxime Coquelin
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