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From: Thomas Monjalon <thomas@monjalon.net>
To: "Tyler Retzlaff" <roretzla@linux.microsoft.com>,
	"Morten Brørup" <mb@smartsharesystems.com>
Cc: dev@dpdk.org, Ajit Khaparde <ajit.khaparde@broadcom.com>,
	Andrew Boyer <andrew.boyer@amd.com>,
	Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
	Bruce Richardson <bruce.richardson@intel.com>,
	Chenbo Xia <chenbox@nvidia.com>,
	Chengwen Feng <fengchengwen@huawei.com>,
	Dariusz Sosnowski <dsosnowski@nvidia.com>,
	David Christensen <drc@linux.vnet.ibm.com>,
	Hyong Youb Kim <hyonkim@cisco.com>,
	Jerin Jacob <jerinj@marvell.com>, Jie Hai <haijie1@huawei.com>,
	Jingjing Wu <jingjing.wu@intel.com>,
	John Daley <johndale@cisco.com>,
	Kevin Laatz <kevin.laatz@intel.com>,
	Kiran Kumar K <kirankumark@marvell.com>,
	Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>,
	Maciej Czekaj <mczekaj@marvell.com>,
	Matan Azrad <matan@nvidia.com>,
	Maxime Coquelin <maxime.coquelin@redhat.com>,
	Nithin Dabilpuram <ndabilpuram@marvell.com>,
	Ori Kam <orika@nvidia.com>, Ruifeng Wang <ruifeng.wang@arm.com>,
	Satha Rao <skoteshwar@marvell.com>,
	Somnath Kotur <somnath.kotur@broadcom.com>,
	Suanming Mou <suanmingm@nvidia.com>,
	Sunil Kumar Kori <skori@marvell.com>,
	Viacheslav Ovsiienko <viacheslavo@nvidia.com>,
	Yisen Zhuang <yisen.zhuang@huawei.com>,
	Yuying Zhang <Yuying.Zhang@intel.com>
Subject: Re: [PATCH v5 00/22] stop using RTE_MARKER extensions
Date: Sat, 24 Feb 2024 12:13:36 +0100	[thread overview]
Message-ID: <3245779.AJdgDx1Vlc@thomas> (raw)
In-Reply-To: <98CBD80474FA8B44BF855DF32C47DC35E9F262@smartserver.smartshare.dk>

24/02/2024 11:42, Morten Brørup:
> From: Tyler Retzlaff [mailto:roretzla@linux.microsoft.com]
> > RTE_MARKER typedefs are a GCC extension unsupported by MSVC. This series
> > hides the markers when building with MSVC and updates libraries and
> > drivers to access compatibly typed pointers to the rte_mbuf struct
> > offsets.
> > 
> > This series, does the following.
> > 
> > Introduces a new macro __rte_marker(type, name) which is used to
> > conditionally expand RTE_MARKER fields empty when building with GCC.
> 
> Important typo: GCC -> MSVC.
> 
> Correct me if I'm wrong: When building with MSVC, the RTE_MARKER fields don't exist at all.

Yes it should trigger a compiler error when using an old marker with MSVC.
So no need of this wrapper __rte_marker().

> > Updates existing inline functions accessing cacheline{0,1} markers in
> > the rte_mbuf struct to stop using the markers and instead uses the mbuf
> > fields directly.
> > 
> > Introduces 2 new inline functions to allow drivers to access rearm_data
> > and rx_descriptor_fields1 descriptors without using the RTE_MARKER
> > fields.
> > 
> > Updates all drivers to use the new inline rte_mbuf struct accessors for
> > rearm_data and rx_descriptor_fields1.
> 
> Accessor functions like these are BS for structures that are part of the public API.

What is BS?

> Nobody will use the accessor functions! When developing an application (or lib or driver), the developer will look at the structure and access the relevant fields directly; why would the developer start looking elsewhere for accessor functions?

Yes that's why we need to reference the accessors inside the mbuf structure.
Also we should check new code (with checkpatch) for not using markers anymore.

> Another alternative would be to remove the rearm_data and rx_descriptor_fields1 fields from the structure, and in the drivers address the first field of the group, and preferably add some static_asserts to check the sequence of the fields they cover. I don't like this alternative, but I'm putting it out there for discussion/inspiration.
> I prefer the union+struct approach to visibly group the fields together.

Unions make the mbuf struct more complicate just for compatibility.

> Overall, I dislike approach taken in this version of the patch series.
> On the surface, it has minimal changes to the mbuf structure.
> But underneath, some of the fields (the markers) may or may not exist, depending on compiler, and this fact is not obvious when looking at the structure. I think this will degrade future MSVC compatibility for both applications, libraries and PMDs.

With appropriate checks, we won't use markers anymore.

> As Thomas stressed, we should take special care of the mbuf structure!
> It has to be modified for MSVC compatibility, so we have to find the best compromise.
> Personally, I prefer the previous approach over this version.
> 
> Maybe we need to compromise on API compatibility to make this a beautiful modification.
> 
> @Thomas, looking at the mbuf and eal patches, what do you think about this version of the series?

I prefer this series with following changes:
- no __rte_marker wrapper
- make sure cache line padding is effective without markers
- no direct access of fields for cache line prefetch
- comments in mbuf
- checkpatch



  reply	other threads:[~2024-02-24 11:13 UTC|newest]

Thread overview: 177+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-30 23:26 [PATCH] replace GCC marker extension with C11 anonymous unions Tyler Retzlaff
2024-01-30 23:26 ` [PATCH] mbuf: " Tyler Retzlaff
2024-01-31  9:18   ` Morten Brørup
2024-01-31 21:09     ` Tyler Retzlaff
2024-01-31 22:39       ` Morten Brørup
2024-01-31 13:49   ` Bruce Richardson
2024-01-31 20:45     ` Tyler Retzlaff
2024-01-31 22:55       ` Morten Brørup
2024-02-13  6:45   ` [PATCH v2] RFC: " Tyler Retzlaff
2024-02-13  6:45     ` [PATCH v2] mbuf: " Tyler Retzlaff
2024-02-13 16:58       ` Morten Brørup
2024-02-13 18:48         ` Tyler Retzlaff
2024-02-13 19:27           ` Morten Brørup
2024-02-13 20:00             ` Tyler Retzlaff
2024-02-13  8:57     ` [PATCH v2] RFC: " Bruce Richardson
2024-02-13 17:09     ` Morten Brørup
2024-02-13 23:33   ` [PATCH v3] RFC deprecate RTE_MARKER in struct rte_mbuf Tyler Retzlaff
2024-02-13 23:33     ` [PATCH v3] mbuf: deprecate GCC marker in rte mbuf struct Tyler Retzlaff
2024-02-14 10:46       ` Morten Brørup
2024-02-14 20:16         ` Tyler Retzlaff
2024-02-14 10:49     ` [PATCH v3] RFC deprecate RTE_MARKER in struct rte_mbuf Morten Brørup
2024-02-26  1:18     ` Stephen Hemminger
2024-02-15  6:21 ` [PATCH v4 00/18] stop using zero sized marker fields Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 01/18] mbuf: deprecate GCC marker in rte mbuf struct Tyler Retzlaff
2024-02-18  2:28     ` fengchengwen
2024-02-18 12:39     ` Thomas Monjalon
2024-02-18 13:07       ` Morten Brørup
2024-02-18 15:22         ` Thomas Monjalon
2024-02-18 16:20           ` Morten Brørup
2024-02-20 17:24           ` Tyler Retzlaff
2024-02-20 17:20       ` Tyler Retzlaff
2024-02-20 17:53         ` Thomas Monjalon
2024-02-20 19:16           ` Thomas Monjalon
2024-02-20 19:37             ` Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 02/18] mbuf: stop using zero sized marker fields Tyler Retzlaff
2024-02-18  2:38     ` fengchengwen
2024-02-15  6:21   ` [PATCH v4 03/18] net/i40e: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 04/18] net/iavf: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 05/18] net/ice: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 06/18] net/ixgbe: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 07/18] net/mlx5: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 08/18] net/sfc: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 09/18] net/bnxt: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 10/18] net/enic: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 11/18] net/fm10k: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 12/18] net/hns3: " Tyler Retzlaff
2024-02-18  3:00     ` fengchengwen
2024-02-15  6:21   ` [PATCH v4 13/18] net/ionic: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 14/18] net/thunderx: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 15/18] net/virtio: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 16/18] net/cnxk: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 17/18] common/idpf: " Tyler Retzlaff
2024-02-15  6:21   ` [PATCH v4 18/18] examples/dma: " Tyler Retzlaff
2024-02-15  9:37   ` [PATCH v4 00/18] " Morten Brørup
2024-02-24  8:21 ` [PATCH v5 00/22] stop using RTE_MARKER extensions Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 01/22] eal: provide macro to expand marker extensions Tyler Retzlaff
2024-02-24 10:51     ` Thomas Monjalon
2024-02-24 11:18       ` Thomas Monjalon
2024-02-24  8:21   ` [PATCH v5 02/22] mbuf: expand rte markers empty when building with MSVC Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 03/22] security: " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 04/22] cryptodev: " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 05/22] mbuf: stop using mbuf cacheline marker fields Tyler Retzlaff
2024-02-24 10:58     ` Thomas Monjalon
2024-02-26 18:20       ` Stephen Hemminger
2024-02-24  8:21   ` [PATCH v5 06/22] mbuf: add mbuf descriptor accessors Tyler Retzlaff
2024-02-24 11:01     ` Thomas Monjalon
2024-02-24  8:21   ` [PATCH v5 07/22] common/idpf: use " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 08/22] net/bnxt: " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 09/22] net/cnxk: " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 10/22] net/enic: " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 11/22] net/fm10k: " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 12/22] net/hns3: " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 13/22] net/i40e: " Tyler Retzlaff
2024-02-24  8:21   ` [PATCH v5 14/22] net/iavf: " Tyler Retzlaff
2024-02-24  8:22   ` [PATCH v5 15/22] net/ice: " Tyler Retzlaff
2024-02-24  8:22   ` [PATCH v5 16/22] net/ionic: " Tyler Retzlaff
2024-02-24  8:22   ` [PATCH v5 17/22] net/ixgbe: " Tyler Retzlaff
2024-02-24  8:22   ` [PATCH v5 18/22] net/mlx5: " Tyler Retzlaff
2024-02-24  8:22   ` [PATCH v5 19/22] net/octeon_ep: " Tyler Retzlaff
2024-02-24  8:22   ` [PATCH v5 20/22] net/sfc: " Tyler Retzlaff
2024-02-24  8:22   ` [PATCH v5 21/22] net/thunderx: " Tyler Retzlaff
2024-02-24  8:22   ` [PATCH v5 22/22] net/virtio: " Tyler Retzlaff
2024-02-24 10:42   ` [PATCH v5 00/22] stop using RTE_MARKER extensions Morten Brørup
2024-02-24 11:13     ` Thomas Monjalon [this message]
2024-02-24 11:23       ` Morten Brørup
2024-02-27  5:41 ` [PATCH v6 00/23] stop and remove RTE_MARKER typedefs Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 01/23] mbuf: add accessors for rearm and Rx descriptor fields Tyler Retzlaff
2024-02-27  9:10     ` Morten Brørup
2024-02-27 17:17       ` Tyler Retzlaff
2024-02-28  8:28         ` Morten Brørup
2024-02-28 16:20           ` Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 02/23] mbuf: consolidate driver asserts for mbuf struct Tyler Retzlaff
2024-02-27 10:02     ` Konstantin Ananyev
2024-03-14 16:51     ` Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 03/23] common/idpf: use mbuf descriptor accessors Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 04/23] net/bnxt: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 05/23] net/cnxk: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 06/23] net/enic: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 07/23] net/fm10k: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 08/23] net/hns3: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 09/23] net/i40e: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 10/23] net/iavf: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 11/23] net/ice: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 12/23] net/ionic: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 13/23] net/ixgbe: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 14/23] net/mlx5: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 15/23] net/octeon_ep: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 16/23] net/sfc: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 17/23] net/thunderx: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 18/23] net/virtio: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 19/23] examples/dma: use mbuf descriptor accessor Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 20/23] mbuf: remove and stop using rte marker fields Tyler Retzlaff
2024-02-27  9:15     ` Morten Brørup
2024-02-27 10:03     ` Konstantin Ananyev
2024-02-27 15:18     ` David Marchand
2024-02-27 16:04       ` Morten Brørup
2024-02-27 17:23       ` Tyler Retzlaff
2024-02-28 10:42         ` David Marchand
2024-02-28 14:03       ` Dodji Seketeli
2024-02-28 14:43         ` David Marchand
2024-02-29 14:50           ` Dodji Seketeli
2024-02-28 14:18     ` David Marchand
2024-02-28 15:01       ` Morten Brørup
2024-02-28 15:33         ` David Marchand
2024-02-28 17:20       ` Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 21/23] security: remove " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 22/23] cryptodev: " Tyler Retzlaff
2024-02-27  5:41   ` [PATCH v6 23/23] devtools: forbid new use of rte marker typedefs Tyler Retzlaff
2024-03-20 22:01 ` [PATCH v7 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-03-20 22:01   ` [PATCH v7 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-03-26 10:16     ` Morten Brørup
2024-03-27 18:14       ` Tyler Retzlaff
2024-03-27 19:45         ` Morten Brørup
2024-03-20 22:01   ` [PATCH v7 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-03-21 10:32     ` Bruce Richardson
2024-03-21 15:31       ` Tyler Retzlaff
2024-03-21 16:19         ` Morten Brørup
2024-03-26 11:12     ` Morten Brørup
2024-03-20 22:01   ` [PATCH v7 3/4] security: " Tyler Retzlaff
2024-03-26 10:28     ` Morten Brørup
2024-03-27 19:59       ` Tyler Retzlaff
2024-03-20 22:01   ` [PATCH v7 4/4] cryptodev: " Tyler Retzlaff
2024-03-26 10:31     ` Morten Brørup
2024-03-27 19:56 ` [PATCH v8 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-03-27 19:56   ` [PATCH v8 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-03-27 19:56   ` [PATCH v8 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-03-27 19:56   ` [PATCH v8 3/4] security: " Tyler Retzlaff
2024-03-27 19:56   ` [PATCH v8 4/4] cryptodev: " Tyler Retzlaff
2024-04-02 20:08 ` [PATCH v9 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-04-02 20:08   ` [PATCH v9 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-04-02 20:08   ` [PATCH v9 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-04-02 20:45     ` Stephen Hemminger
2024-04-02 20:51       ` Tyler Retzlaff
2024-04-02 20:08   ` [PATCH v9 3/4] security: " Tyler Retzlaff
2024-04-02 20:08   ` [PATCH v9 4/4] cryptodev: " Tyler Retzlaff
2024-04-03 17:53 ` [PATCH v10 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-04-03 17:53   ` [PATCH v10 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-04-03 21:49     ` Stephen Hemminger
2024-04-03 17:53   ` [PATCH v10 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-04-03 19:32     ` Morten Brørup
2024-04-03 22:45       ` Tyler Retzlaff
2024-04-03 21:49     ` Stephen Hemminger
2024-04-03 17:53   ` [PATCH v10 3/4] security: " Tyler Retzlaff
2024-04-03 21:50     ` Stephen Hemminger
2024-04-03 17:53   ` [PATCH v10 4/4] cryptodev: " Tyler Retzlaff
2024-04-03 21:50     ` Stephen Hemminger
2024-04-04 17:51 ` [PATCH v11 0/4] remove use of RTE_MARKER fields in libraries Tyler Retzlaff
2024-04-04 17:51   ` [PATCH v11 1/4] net/i40e: use inline prefetch function Tyler Retzlaff
2024-04-04 17:51   ` [PATCH v11 2/4] mbuf: remove rte marker fields Tyler Retzlaff
2024-04-04 17:51   ` [PATCH v11 3/4] security: " Tyler Retzlaff
2024-04-04 17:51   ` [PATCH v11 4/4] cryptodev: " Tyler Retzlaff
2024-06-19 15:01 ` [PATCH v12 0/4] remove use of RTE_MARKER fields in libraries David Marchand
2024-06-19 15:01   ` [PATCH v12 1/4] net/i40e: use mbuf prefetch helper David Marchand
2024-06-19 15:01   ` [PATCH v12 2/4] mbuf: remove marker fields David Marchand
2024-06-19 15:01   ` [PATCH v12 3/4] security: " David Marchand
2024-06-19 15:01   ` [PATCH v12 4/4] cryptodev: " David Marchand
2024-06-19 17:30   ` [PATCH v12 0/4] remove use of RTE_MARKER fields in libraries David Marchand

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