diff --git a/src/libcore/sync/atomic.rs b/src/libcore/sync/atomic.rs index a2352c08e7316..fae95ca5cdb36 100644 --- a/src/libcore/sync/atomic.rs +++ b/src/libcore/sync/atomic.rs @@ -134,16 +134,10 @@ 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. +/// A common use case for `spin_loop_hint` is implementing bounded optimistic spinning in a CAS +/// loop in synchronization primitives. To avoid problems like priority inversion, it is strongly +/// recommended that the spin loop is terminated after a finite amount of iterations and an +/// appropriate blocking syscall is made. /// /// **Note**: On platforms that do not support receiving spin-loop hints this function does not /// do anything at all.