fix wake_one test + better timeouts + add/clean comments

Author: LorrensP-2158466

tests/pass-dep/concurrency/freebsd-futex.rs

@@ -28,8 +28,9 @@ fn wait_wake() {
                 );
             }
         });
-        thread::yield_now();
-        let mut timeout = libc::timespec { tv_sec: 0, tv_nsec: 400_000_000 };
+
+        // 10ms should be enough.
+        let mut timeout = libc::timespec { tv_sec: 0, tv_nsec: 10_000_000 };
         let timeout_size_arg =
             ptr::without_provenance_mut::<libc::c_void>(mem::size_of::<libc::timespec>());
         unsafe {
@@ -51,13 +52,13 @@ fn wait_wake() {
     }
 
     fn wake_two_of_three() {
-        // We create 2 threads that wait on a futex with a 500ms timeout.
-        // The main thread wakes up 1 thread waiting on this futex and after this
-        // checks that only 1 thread woke up and the other timed out.
+        // We create 2 threads that wait on a futex with a 100ms timeout.
+        // The main thread wakes up 2 threads waiting on this futex and after this
+        // checks that only those threads woke up and the other one timed out.
         static mut FUTEX: u32 = 0;
 
         fn waiter() -> bool {
-            let mut timeout = libc::timespec { tv_sec: 0, tv_nsec: 500_000_000 };
+            let mut timeout = libc::timespec { tv_sec: 0, tv_nsec: 100_000_000 };
             let timeout_size_arg =
                 ptr::without_provenance_mut::<libc::c_void>(mem::size_of::<libc::timespec>());
             unsafe {
@@ -77,7 +78,9 @@ fn wait_wake() {
         let t2 = thread::spawn(waiter);
         let t3 = thread::spawn(waiter);
 
+        // Run all the waiters, so they can go to sleep.
         thread::yield_now();
+
         // Wake up 2 thread and make sure 1 is still waiting.
         unsafe {
             assert_eq!(