This routine obtains both the current scheduling policy and
    associated scheduling parameters of the thread specified by the
    thread argument.

    The priority value returned in the param structure is the value
    specified either in the attr argument passed to pthread_create()
    or by the most recent call to pthread_setschedparam() that
    affects the target thread.

    This routine differs from pthread_attr_getschedpolicy() and
    pthread_attr_getschedparam(), in that those routines get the
    scheduling policy and parameter attributes that are used to
    establish the priority and scheduling policy of a new thread
    when it is created. This routine, however, obtains the scheduling
    policy and parameters of an existing thread.