message: Make semaphore always sched_yield
diff: @@ -29,7 +29,8 @@ impl Semaphore {
  }
  loop {
  while self.lock.load(Ordering::Acquire) < 1 {
  - spin_loop();
  + //spin_loop();
  + Sys::sched_yield();
  }
  let tmp = self.lock.fetch_sub(1, Ordering::AcqRel);
  if tmp >= 1 {
  