0                  Indicates success.
    -1                 Indicates failure; errno is set to the
                       following value:

                       o  EINVAL - The clock_id argument does not
                          specify a known clock, or the tp argument
                          is outside the range for the given clock_id
                          or specifies a nanosecond value less than 0
                          or greater than or equal to 1 billion.

                       o  EPERM - The requesting process does not
                          have the appropriate privilege to set the
                          specified clock.