From cb1e0c75b09f5aeba6b270347f9c3fcbac73fd49 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?D=C3=A1niel=20Buga?= Date: Sun, 31 Aug 2025 10:20:03 +0200 Subject: [PATCH 1/2] Prefer pointer-sized atomic operations --- embassy-executor/CHANGELOG.md | 2 ++ embassy-executor/src/raw/mod.rs | 10 ++++++++-- embassy-executor/src/raw/state_atomics.rs | 21 ++++++++++++++++----- 3 files changed, 26 insertions(+), 7 deletions(-) diff --git a/embassy-executor/CHANGELOG.md b/embassy-executor/CHANGELOG.md index f301429c0..450536989 100644 --- a/embassy-executor/CHANGELOG.md +++ b/embassy-executor/CHANGELOG.md @@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0 ## Unreleased - ReleaseDate +- Fixed performance regression on some ESP32 MCUs. + ## 0.9.0 - 2025-08-26 - Added `extern "Rust" fn __embassy_time_queue_item_from_waker` diff --git a/embassy-executor/src/raw/mod.rs b/embassy-executor/src/raw/mod.rs index 4b17d4982..b7c6b7bc3 100644 --- a/embassy-executor/src/raw/mod.rs +++ b/embassy-executor/src/raw/mod.rs @@ -12,8 +12,14 @@ mod run_queue; #[cfg_attr(all(cortex_m, target_has_atomic = "32"), path = "state_atomics_arm.rs")] -#[cfg_attr(all(not(cortex_m), target_has_atomic = "8"), path = "state_atomics.rs")] -#[cfg_attr(not(target_has_atomic = "8"), path = "state_critical_section.rs")] +#[cfg_attr( + all(not(cortex_m), any(target_has_atomic = "8", target_has_atomic = "32")), + path = "state_atomics.rs" +)] +#[cfg_attr( + not(any(target_has_atomic = "8", target_has_atomic = "32")), + path = "state_critical_section.rs" +)] mod state; #[cfg(feature = "trace")] diff --git a/embassy-executor/src/raw/state_atomics.rs b/embassy-executor/src/raw/state_atomics.rs index e813548ae..6675875be 100644 --- a/embassy-executor/src/raw/state_atomics.rs +++ b/embassy-executor/src/raw/state_atomics.rs @@ -1,4 +1,15 @@ -use core::sync::atomic::{AtomicU8, Ordering}; +// Prefer pointer-width atomic operations, as narrower ones may be slower. +#[cfg(all(target_pointer_width = "32", target_has_atomic = "32"))] +type AtomicState = core::sync::atomic::AtomicU32; +#[cfg(not(all(target_pointer_width = "32", target_has_atomic = "32")))] +type AtomicState = core::sync::atomic::AtomicU8; + +#[cfg(all(target_pointer_width = "32", target_has_atomic = "32"))] +type StateBits = u32; +#[cfg(not(all(target_pointer_width = "32", target_has_atomic = "32")))] +type StateBits = u8; + +use core::sync::atomic::Ordering; #[derive(Clone, Copy)] pub(crate) struct Token(()); @@ -11,18 +22,18 @@ pub(crate) fn locked(f: impl FnOnce(Token) -> R) -> R { } /// Task is spawned (has a future) -pub(crate) const STATE_SPAWNED: u8 = 1 << 0; +pub(crate) const STATE_SPAWNED: StateBits = 1 << 0; /// Task is in the executor run queue -pub(crate) const STATE_RUN_QUEUED: u8 = 1 << 1; +pub(crate) const STATE_RUN_QUEUED: StateBits = 1 << 1; pub(crate) struct State { - state: AtomicU8, + state: AtomicState, } impl State { pub const fn new() -> State { Self { - state: AtomicU8::new(0), + state: AtomicState::new(0), } } From 5a282639029f1eead743ddc26d19ed11fdddd803 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?D=C3=A1niel=20Buga?= Date: Sun, 31 Aug 2025 10:39:04 +0200 Subject: [PATCH 2/2] Prefer word-sized state in CS impl --- .../src/raw/state_critical_section.rs | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/embassy-executor/src/raw/state_critical_section.rs b/embassy-executor/src/raw/state_critical_section.rs index ec08f2f58..b69a6ac66 100644 --- a/embassy-executor/src/raw/state_critical_section.rs +++ b/embassy-executor/src/raw/state_critical_section.rs @@ -3,13 +3,18 @@ use core::cell::Cell; pub(crate) use critical_section::{with as locked, CriticalSection as Token}; use critical_section::{CriticalSection, Mutex}; +#[cfg(target_arch = "avr")] +type StateBits = u8; +#[cfg(not(target_arch = "avr"))] +type StateBits = usize; + /// Task is spawned (has a future) -pub(crate) const STATE_SPAWNED: u8 = 1 << 0; +pub(crate) const STATE_SPAWNED: StateBits = 1 << 0; /// Task is in the executor run queue -pub(crate) const STATE_RUN_QUEUED: u8 = 1 << 1; +pub(crate) const STATE_RUN_QUEUED: StateBits = 1 << 1; pub(crate) struct State { - state: Mutex>, + state: Mutex>, } impl State { @@ -19,11 +24,11 @@ impl State { } } - fn update(&self, f: impl FnOnce(&mut u8) -> R) -> R { + fn update(&self, f: impl FnOnce(&mut StateBits) -> R) -> R { critical_section::with(|cs| self.update_with_cs(cs, f)) } - fn update_with_cs(&self, cs: CriticalSection<'_>, f: impl FnOnce(&mut u8) -> R) -> R { + fn update_with_cs(&self, cs: CriticalSection<'_>, f: impl FnOnce(&mut StateBits) -> R) -> R { let s = self.state.borrow(cs); let mut val = s.get(); let r = f(&mut val);