NAME

    pthread_setprio - Changes the current priority of a thread

 SYNOPSIS

     #include <pthread.h>

     int pthread_setprio( pthread_t thread,
                          int       priority );

 PARAMETERS

     thread              Thread whose priority is changed.

     priority            New priority value of the thread specified
                         in thread.  The priority value depends on
                         scheduling policy. Valid values fall within
                         one of the following ranges:

                         o   PRI_OTHER_MIN <= priority <= PRI_OTHER_MAX

                         o   PRI_FIFO_MIN <= priority <= PRI_FIFO_MAX

                         o   PRI_RR_MIN <= priority <= PRI_RR_MAX

                         o   PRI_FG_MIN_NP <= priority <= PRI_FG_MAX_NP

                         o   PRI_BG_MIN_NP <= priority <= PRI_BG_MAX_NP

 If you create a new  thread  without  specifying  a  threads  attributes
 object  that contains a changed priority attribute, the default priority
 of the newly created thread is the midpoint  between  PRI_OTHER_MIN  and
 PRI_OTHER_MAX  (the midpoint between the minimum and the maximum for the
 SCHED_OTHER policy).

 When you call this routine 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 use it.

 DESCRIPTION

 The pthread_setprio() routine changes the current priority of a  thread.
 A  thread  can  change its own priority using the identifier returned by
 pthread_self().

 Changing the priority of a thread can cause it to start executing or  be
 preempted  by  another  thread. The effect of setting different priority
 values depends on the scheduling priority assigned to  the  thread.  The
 initial scheduling priority is set by calling the pthread_attr_setprio()
 routine.

 Note that pthread_attr_setprio() sets the  priority  attribute  that  is
 used to establish the priority of a new thread when it is created.  How-
 ever, pthread_setprio() changes the priority of an existing thread.

 RETURN VALUES

 If successful, this routine returns the previous priority.

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

    Return              Error       Description
    ___________________________________________________________
    Previous priority               Successful completion.

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

    -1                 [ENOTSUP]    An attempt is made to set the  policy
 				   to an unsupported value.

    -1                 [ESRCH]      The value specified by thread does
 				   not refer to an existing thread.

    -1                 [EPERM]      The caller does not have the
 				   appropriate privileges  to  set  the
 			 	   priority of the specified thread.

 RELATED INFORMATION

     FUNCTIONS:  pthread_attr_setprio
                 pthread_attr_setsched
                 pthread_create
                 pthread_self
                 pthread_setscheduler