NAME

    pthread_attr_setprio - Changes the scheduling priority attribute of
                           thread creation

 SYNOPSIS

     #include <pthread.h>

     int pthread_attr_setprio( pthread_attr_t *attr,
                                int priority );

 PARAMETERS

     attr                Thread attributes object modified.

     priority            New value for the priority attribute.  The
                         priority attribute depends on scheduling
                         policy. Valid values fall within one of the
                         following ranges:

                         o    PRI_OTHER_MIN <= priority <= PRI_OTHER_MAX
                              (use with the SCHED_OTHER policy)

                         o    PRI_FIFO_MIN <= priority <= PRI_FIFO_MAX
                              (use with the SCHED_FIFO policy)

                         o    PRI_RR_MIN <= priority <= PRI_RR_MAX
                              (use with the SCHED_RR policy)

                         o    PRI_FG_MIN_NP <= priority <= PRI_FG_MAX_NP
                              (use with the SCHED_FG_NP policy)

                         o    PRI_BG_MIN_NP <= priority <= PRI_BG_MAX_NP
                              (use with the SCHED_BG_NP policy)

 The  default  priority  is  the  midpoint  between   PRI_OTHER_MIN   and
 PRI_OTHER_MAX.  To  specify  a  minimum  or  maximum  priority,  use the
 appropriate  symbol;  for  example,  PRI_FIFO_MIN  or  PRI_FIFO_MAX.  To
 specify  a  value  between  the  minimum and maximum, use an appropriate
 arithmetic expression.   For  example,  to  specify  a  priority  midway
 between  the  minimum and maximum for the Round Robin scheduling policy,
 specify the following concept using your programming language's syntax:
      pri_rr_mid = (PRI_RR_MIN + PRI_RR_MAX)/2

 If your expression results in a value outside the range  of  minimum  to
 maximum, an error results when you attempt to use it.

 DESCRIPTION

 The  pthread_attr_setprio()  routine  sets  the  execution  priority  of
 threads  that  are  created using the attributes object specified by the
 attr parameter.

 By default, a created thread inherits the priority of the thread calling
 pthread_create().  To  specify a priority using this routine, scheduling
 inheritance must be disabled at the time the thread is created.   Before
 calling      this      routine      and      pthread_create(),      call
 pthread_attr_setinheritsched()      and      specify      the      value
 PTHREAD_DEFAULT_SCHED for the inherit parameter.

 An application specifies priority only to express the urgency of execut-
 ing  the  thread relative to other threads. Priority is not used to con-
 trol mutual exclusion when accessing shared data.

 RETURN VALUES

 If the function fails, errno may be set to one of the following values:

    Return   Error      Description
    ___________________________________________________________
    0                   Successful completion.

    -1       [EINVAL]   The value specified by attr is invalid.

    -1       [ERANGE]   One or more parameters supplied have an
                        invalid value.
    -1       [EPERM]    The caller does not have the appropriate
                        privileges to set the priority of the
                        specified thread.

 RELATED INFORMATION

     FUNCTIONS:  pthread_attr_create
                 pthread_attr_getprio
                 pthread_attr_setinheritsched
                 pthread_create