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Reduce backoff spinning/usage #1038

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Reduce backoff spinning/usage #1038

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423717a
reduce backoff spinning/usage
ibraheemdev Nov 7, 2023
252665d
change `SPIN_LIMIT` to 4
ibraheemdev May 2, 2024
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15 changes: 0 additions & 15 deletions crossbeam-channel/src/context.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -138,21 +138,6 @@ impl Context {
/// If the deadline is reached, `Selected::Aborted` will be selected.
#[inline]
pub fn wait_until(&self, deadline: Option<Instant>) -> Selected {
// Spin for a short time, waiting until an operation is selected.
let backoff = Backoff::new();
loop {
let sel = Selected::from(self.inner.select.load(Ordering::Acquire));
if sel != Selected::Waiting {
return sel;
}

if backoff.is_completed() {
break;
} else {
backoff.snooze();
}
}

loop {
// Check whether an operation has been selected.
let sel = Selected::from(self.inner.select.load(Ordering::Acquire));
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5 changes: 3 additions & 2 deletions crossbeam-utils/src/backoff.rs
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Expand Up @@ -2,8 +2,9 @@ use crate::primitive::hint;
use core::cell::Cell;
use core::fmt;

const SPIN_LIMIT: u32 = 6;
const YIELD_LIMIT: u32 = 10;
// https://github.com/oneapi-src/oneTBB/blob/v2021.5.0/include/oneapi/tbb/detail/_utils.h#L46-L48
const SPIN_LIMIT: u32 = 4;
const YIELD_LIMIT: u32 = 6;

/// Performs exponential backoff in spin loops.
///
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