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Remove wrong advice about spin locks from spin_loop_hint docs #67798

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12 changes: 2 additions & 10 deletions src/libcore/sync/atomic.rs
Original file line number Diff line number Diff line change
Expand Up @@ -134,16 +134,8 @@ use crate::hint::spin_loop;
/// This function is different from [`std::thread::yield_now`] which directly yields to the
/// system's scheduler, whereas `spin_loop_hint` does not interact with the operating system.
///
/// Spin locks can be very efficient for short lock durations because they do not involve context
/// switches or interaction with the operating system. For long lock durations they become wasteful
/// however because they use CPU cycles for the entire lock duration, and using a
/// [`std::sync::Mutex`] is likely the better approach. If actively spinning for a long time is
/// required, e.g. because code polls a non-blocking API, calling [`std::thread::yield_now`]
/// or [`std::thread::sleep`] may be the best option.
///
/// **Note**: Spin locks are based on the underlying assumption that another thread will release
/// the lock 'soon'. In order for this to work, that other thread must run on a different CPU or
/// core (at least potentially). Spin locks do not work efficiently on single CPU / core platforms.
/// If actively spinning for a long time is required, e.g. because code polls a non-blocking API,
/// calling [`std::thread::yield_now`] or [`std::thread::sleep`] may be the best option.
///
/// **Note**: On platforms that do not support receiving spin-loop hints this function does not
/// do anything at all.
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