From: Jakub Kicinski <kuba@kernel.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: linux-s390@vger.kernel.org, ntfs3@lists.linux.dev,
Yury Norov <yury.norov@gmail.com>,
Przemek Kitszel <przemyslaw.kitszel@intel.com>,
David Ahern <dsahern@kernel.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
dm-devel@redhat.com, linux-kernel@vger.kernel.org,
Eric Dumazet <edumazet@google.com>,
netdev@vger.kernel.org, Alexander Potapenko <glider@google.com>,
Simon Horman <simon.horman@corigine.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2 04/13] linkmode: convert linkmode_{test,set,clear,mod}_bit() to macros
Date: Wed, 18 Oct 2023 17:27:54 -0700 [thread overview]
Message-ID: <20231018172754.3eec4885@kernel.org> (raw)
In-Reply-To: <20231016165247.14212-5-aleksander.lobakin@intel.com>
On Mon, 16 Oct 2023 18:52:38 +0200 Alexander Lobakin wrote:
> Since commit b03fc1173c0c ("bitops: let optimize out non-atomic bitops
> on compile-time constants"), the non-atomic bitops are macros which can
> be expanded by the compilers into compile-time expressions, which will
> result in better optimized object code. Unfortunately, turned out that
> passing `volatile` to those macros discards any possibility of
> optimization, as the compilers then don't even try to look whether
> the passed bitmap is known at compilation time. In addition to that,
> the mentioned linkmode helpers are marked with `inline`, not
> `__always_inline`, meaning that it's not guaranteed some compiler won't
> uninline them for no reason, which will also effectively prevent them
> from being optimized (it's a well-known thing the compilers sometimes
> uninline `2 + 2`).
> Convert linkmode_*_bit() from inlines to macros. Their calling
> convention are 1:1 with the corresponding bitops, so that it's not even
> needed to enumerate and map the arguments, only the names. No changes in
> vmlinux' object code (compiled by LLVM for x86_64) whatsoever, but that
> doesn't necessarily means the change is meaningless.
Acked-by: Jakub Kicinski <kuba@kernel.org>
This one can go in with the rest, it's trivial enough.
WARNING: multiple messages have this Message-ID (diff)
From: Jakub Kicinski <kuba@kernel.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Yury Norov <yury.norov@gmail.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Alexander Potapenko <glider@google.com>,
Eric Dumazet <edumazet@google.com>,
David Ahern <dsahern@kernel.org>,
Przemek Kitszel <przemyslaw.kitszel@intel.com>,
Simon Horman <simon.horman@corigine.com>,
netdev@vger.kernel.org, linux-btrfs@vger.kernel.org,
dm-devel@redhat.com, ntfs3@lists.linux.dev,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 04/13] linkmode: convert linkmode_{test,set,clear,mod}_bit() to macros
Date: Wed, 18 Oct 2023 17:27:54 -0700 [thread overview]
Message-ID: <20231018172754.3eec4885@kernel.org> (raw)
In-Reply-To: <20231016165247.14212-5-aleksander.lobakin@intel.com>
On Mon, 16 Oct 2023 18:52:38 +0200 Alexander Lobakin wrote:
> Since commit b03fc1173c0c ("bitops: let optimize out non-atomic bitops
> on compile-time constants"), the non-atomic bitops are macros which can
> be expanded by the compilers into compile-time expressions, which will
> result in better optimized object code. Unfortunately, turned out that
> passing `volatile` to those macros discards any possibility of
> optimization, as the compilers then don't even try to look whether
> the passed bitmap is known at compilation time. In addition to that,
> the mentioned linkmode helpers are marked with `inline`, not
> `__always_inline`, meaning that it's not guaranteed some compiler won't
> uninline them for no reason, which will also effectively prevent them
> from being optimized (it's a well-known thing the compilers sometimes
> uninline `2 + 2`).
> Convert linkmode_*_bit() from inlines to macros. Their calling
> convention are 1:1 with the corresponding bitops, so that it's not even
> needed to enumerate and map the arguments, only the names. No changes in
> vmlinux' object code (compiled by LLVM for x86_64) whatsoever, but that
> doesn't necessarily means the change is meaningless.
Acked-by: Jakub Kicinski <kuba@kernel.org>
This one can go in with the rest, it's trivial enough.
next prev parent reply other threads:[~2023-10-19 6:38 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-16 16:52 [PATCH v2 00/13] ip_tunnel: convert __be16 tunnel flags to bitmaps Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 01/13] bitops: add missing prototype check Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 02/13] bitops: make BYTES_TO_BITS() treewide-available Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 03/13] bitops: let the compiler optimize {__,}assign_bit() Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 04/13] linkmode: convert linkmode_{test, set, clear, mod}_bit() to macros Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 04/13] linkmode: convert linkmode_{test,set,clear,mod}_bit() " Alexander Lobakin
2023-10-19 0:27 ` Jakub Kicinski [this message]
2023-10-19 0:27 ` Jakub Kicinski
2023-10-16 16:52 ` [PATCH v2 05/13] s390/cio: rename bitmap_size() -> idset_bitmap_size() Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 06/13] fs/ntfs3: add prefix to bitmap_size() and use BITS_TO_U64() Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 07/13] btrfs: rename bitmap_set_bits() -> btrfs_bitmap_set_bits() Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 08/13] bitmap: introduce generic optimized bitmap_size() Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 09/13] bitmap: make bitmap_{get, set}_value8() use bitmap_{read, write}() Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 09/13] bitmap: make bitmap_{get,set}_value8() use bitmap_{read,write}() Alexander Lobakin
2023-10-16 17:48 ` Yury Norov
2023-10-16 17:48 ` Yury Norov
2023-10-16 16:52 ` [PATCH v2 10/13] ip_tunnel: use a separate struct to store tunnel params in the kernel Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 11/13] ip_tunnel: convert __be16 tunnel flags to bitmaps Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-19 0:27 ` Jakub Kicinski
2023-10-19 0:27 ` Jakub Kicinski
2023-10-20 7:41 ` Alexander Potapenko
2023-10-20 12:30 ` Yury Norov
2023-11-02 11:48 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 12/13] lib/bitmap: add compile-time test for __assign_bit() optimization Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 16:52 ` [PATCH v2 13/13] lib/bitmap: add tests for IP tunnel flags conversion helpers Alexander Lobakin
2023-10-16 16:52 ` Alexander Lobakin
2023-10-16 17:54 ` [PATCH v2 00/13] ip_tunnel: convert __be16 tunnel flags to bitmaps Yury Norov
2023-10-16 17:54 ` Yury Norov
2023-10-20 12:46 ` Yury Norov
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=20231018172754.3eec4885@kernel.org \
--to=kuba@kernel.org \
--cc=aleksander.lobakin@intel.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=dm-devel@redhat.com \
--cc=dsahern@kernel.org \
--cc=edumazet@google.com \
--cc=glider@google.com \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux@rasmusvillemoes.dk \
--cc=netdev@vger.kernel.org \
--cc=ntfs3@lists.linux.dev \
--cc=przemyslaw.kitszel@intel.com \
--cc=simon.horman@corigine.com \
--cc=yury.norov@gmail.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.