0                  Indicates success. The requested time has
                       elapsed.
    -1                 Indicates failure. The function call was
                       unsuccessful or was interrupted by a signal;
                       errno is set to one of the following values:

                       o  EINTR - The nanosleep function was
                          interrupted by a signal.

                       o  EINVAL - The rqtp argument specified a
                          nanosecond value less than 0 or greater
                          than or equal to 1 billion.