From: "Mattias Rönnblom" <hofors@lysator.liu.se>
To: Ruifeng Wang <ruifeng.wang@arm.com>,
thomas@monjalon.net, david.marchand@redhat.com
Cc: dev@dpdk.org, konstantin.v.ananyev@yandex.ru,
honnappa.nagarahalli@arm.com, nd@arm.com
Subject: Re: [PATCH] eal: add notes to SMP memory barrier APIs
Date: Thu, 22 Jun 2023 20:19:30 +0200 [thread overview]
Message-ID: <4954a01e-53e3-c070-d737-a60c0042c736@lysator.liu.se> (raw)
In-Reply-To: <20230621064420.163931-1-ruifeng.wang@arm.com>
On 2023-06-21 08:44, Ruifeng Wang wrote:
> The rte_smp_xx() APIs are deprecated. But it is not mentioned
> in the function header.
> Added notes in function header for clarification.
>
> Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
> ---
> lib/eal/include/generic/rte_atomic.h | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/lib/eal/include/generic/rte_atomic.h b/lib/eal/include/generic/rte_atomic.h
> index 58df843c54..542a2c16ff 100644
> --- a/lib/eal/include/generic/rte_atomic.h
> +++ b/lib/eal/include/generic/rte_atomic.h
> @@ -55,6 +55,11 @@ static inline void rte_rmb(void);
> * Guarantees that the LOAD and STORE operations that precede the
> * rte_smp_mb() call are globally visible across the lcores
> * before the LOAD and STORE operations that follows it.
> + *
> + * @note
> + * This function is deprecated. It adds complexity to the memory model
> + * used by this project. C11 memory model should always be used.
> + * rte_atomic_thread_fence() should be used instead.
It's somewhat confusing to learn I should use the C11 memory model, and
then in the next sentence that I should call a function which is not in C11.
I think it would be helpful to say which memory_model parameters should
be used to replace the rte_smp_*mb() calls, and if there are any
difference in semantics between the Linux kernel-style barriers and
their C11 (near-)equivalents.
Is there some particular reason these functions aren't marked
__rte_deprecated? Too many warnings?
> */
> static inline void rte_smp_mb(void);
>
> @@ -64,6 +69,11 @@ static inline void rte_smp_mb(void);
> * Guarantees that the STORE operations that precede the
> * rte_smp_wmb() call are globally visible across the lcores
> * before the STORE operations that follows it.
> + *
> + * @note
> + * This function is deprecated. It adds complexity to the memory model
> + * used by this project. C11 memory model should always be used.
> + * rte_atomic_thread_fence() should be used instead.
> */
> static inline void rte_smp_wmb(void);
>
> @@ -73,6 +83,11 @@ static inline void rte_smp_wmb(void);
> * Guarantees that the LOAD operations that precede the
> * rte_smp_rmb() call are globally visible across the lcores
> * before the LOAD operations that follows it.
> + *
> + * @note
> + * This function is deprecated. It adds complexity to the memory model
> + * used by this project. C11 memory model should always be used.
> + * rte_atomic_thread_fence() should be used instead.
> */
> static inline void rte_smp_rmb(void);
> ///@}
next prev parent reply other threads:[~2023-06-22 18:19 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-21 6:44 Ruifeng Wang
2023-06-21 7:29 ` Thomas Monjalon
2023-06-25 7:55 ` Ruifeng Wang
2023-06-22 18:19 ` Mattias Rönnblom [this message]
2023-06-23 21:51 ` Tyler Retzlaff
2023-06-25 8:45 ` Ruifeng Wang
2023-06-25 15:40 ` Thomas Monjalon
2023-06-25 8:17 ` Ruifeng Wang
2023-06-29 19:28 ` Mattias Rönnblom
2023-07-03 6:12 ` Ruifeng Wang
2023-06-26 7:12 ` [PATCH v2] " Ruifeng Wang
2023-06-29 19:43 ` Mattias Rönnblom
2023-07-03 7:02 ` Ruifeng Wang
2023-07-04 12:08 ` Mattias Rönnblom
2023-07-03 9:56 ` [PATCH v3] " Ruifeng Wang
2023-07-28 9:17 ` Thomas Monjalon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4954a01e-53e3-c070-d737-a60c0042c736@lysator.liu.se \
--to=hofors@lysator.liu.se \
--cc=david.marchand@redhat.com \
--cc=dev@dpdk.org \
--cc=honnappa.nagarahalli@arm.com \
--cc=konstantin.v.ananyev@yandex.ru \
--cc=nd@arm.com \
--cc=ruifeng.wang@arm.com \
--cc=thomas@monjalon.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).