From: Boqun Feng <boqun@kernel.org>
To: Gary Guo <gary@garyguo.net>
Cc: FUJITA Tomonori <tomo@aliasing.net>,
boqun.feng@gmail.com, ojeda@kernel.org, peterz@infradead.org,
will@kernel.org, a.hindborg@kernel.org, aliceryhl@google.com,
bjorn3_gh@protonmail.com, dakr@kernel.org, lossin@kernel.org,
mark.rutland@arm.com, tmgross@umich.edu,
rust-for-linux@vger.kernel.org,
FUJITA Tomonori <fujita.tomonori@gmail.com>
Subject: Re: [PATCH v1 1/2] rust: sync: atomic: Add perfromance-optimal Flag type for atomic booleans
Date: Wed, 28 Jan 2026 10:07:17 -0800 [thread overview]
Message-ID: <aXpQVW3c8vDfbkLP@tardis.local> (raw)
In-Reply-To: <aXpFEhJxbF6cRhAZ@tardis.local>
On Wed, Jan 28, 2026 at 09:19:14AM -0800, Boqun Feng wrote:
[...]
> > > + #[inline(always)]
> > > + pub fn get_mut(&mut self) -> &mut bool {
> > > + &mut self.0.get_mut().bool_field
> > > + }
> > > +
> > > + /// Loads the value from the atomic flag.
> > > + #[inline(always)]
> > > + pub fn load<Ordering: ordering::AcquireOrRelaxed>(&self, o: Ordering) -> bool {
> > > + self.0.load(o).bool_field
>
> For load(), xchg() and cmpxchg(), I think we should not use
> `.bool_field`, because we know that `padding` is always zero, but
> compilers don't. Using `.bool_field` will make the compiler generate i32
> to i8 or a bit mask instruction to get the boolean. We need to implement
> `From<Flag>` for `bool` and use `.into()` here.
>
Scratch this for a moment, I need to do some more investigation.
Regards,
Boqun
> Regards,
> Boqun
>
>
[..]
next prev parent reply other threads:[~2026-01-28 18:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-28 11:51 [PATCH v1 0/2] rust: sync: Add AtomicFlag type FUJITA Tomonori
2026-01-28 11:51 ` [PATCH v1 1/2] rust: sync: atomic: Add perfromance-optimal Flag type for atomic booleans FUJITA Tomonori
2026-01-28 13:41 ` Gary Guo
2026-01-28 17:19 ` Boqun Feng
2026-01-28 18:07 ` Boqun Feng [this message]
2026-01-28 23:22 ` FUJITA Tomonori
2026-01-28 23:56 ` Boqun Feng
2026-01-29 0:40 ` FUJITA Tomonori
2026-01-28 11:52 ` [PATCH v1 2/2] rust: list: Use AtomicFlag in AtomicTracker FUJITA Tomonori
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