Spotted here:

```
void SpinYield::report(outputStream* s) const {
  ...
  if (_sleep_time.value() != 0) { // Report sleep duration, if slept.
    separator = print_separator(s, separator);
    s->print("sleep = " UINT64_FORMAT " usecs",
             _sleep_time.milliseconds());
  }
 ...
}
```

The message says "usecs", but we get `milliseconds()`. Should get microseconds instead.