1PTHREAD_SETSCHEDPRIO(P)    POSIX Programmer's Manual   PTHREAD_SETSCHEDPRIO(P)
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NAME

6       pthread_setschedprio  -  dynamic  thread  scheduling  parameters access
7       (REALTIME THREADS)
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SYNOPSIS

10       #include <pthread.h>
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12       int pthread_setschedprio(pthread_t thread, int prio);
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DESCRIPTION

16       The pthread_setschedprio() function shall set the  scheduling  priority
17       for the thread whose thread ID is given by thread to the value given by
18       prio. See Scheduling Policies for a description on  how  this  function
19       call  affects the ordering of the thread in the thread list for its new
20       priority.
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22       If the pthread_setschedprio() function fails, the  scheduling  priority
23       of the target thread shall not be changed.
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RETURN VALUE

26       If  successful,  the pthread_setschedprio() function shall return zero;
27       otherwise, an error number shall be returned to indicate the error.
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ERRORS

30       The pthread_setschedprio() function may fail if:
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32       EINVAL The value of prio is invalid for the scheduling  policy  of  the
33              specified thread.
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35       ENOTSUP
36              An attempt was made to set the priority to an unsupported value.
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38       EPERM  The  caller  does not have the appropriate permission to set the
39              scheduling policy of the specified thread.
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41       EPERM  The implementation does not allow the application to modify  the
42              priority to the value specified.
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44       ESRCH  The  value  specified  by  thread  does not refer to an existing
45              thread.
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48       The pthread_setschedprio() function shall not return an error  code  of
49       [EINTR].
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51       The following sections are informative.
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EXAMPLES

54       None.
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APPLICATION USAGE

57       None.
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RATIONALE

60       The  pthread_setschedprio()  function provides a way for an application
61       to temporarily raise its priority and then lower it again, without hav‐
62       ing  the undesired side effect of yielding to other threads of the same
63       priority. This is necessary if the application is to implement its  own
64       strategies  for  bounding  priority inversion, such as priority inheri‐
65       tance or priority ceilings.  This capability is especially important if
66       the  implementation  does not support the Thread Priority Protection or
67       Thread Priority Inheritance options, but even if those options are sup‐
68       ported it is needed if the application is to bound priority inheritance
69       for other resources, such as semaphores.
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71       The standard developers considered that while it  might  be  preferable
72       conceptually  to  solve  this problem by modifying the specification of
73       pthread_setschedparam(), it was too late to  make  such  a  change,  as
74       there may be implementations that would need to be changed.  Therefore,
75       this new function was introduced.
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FUTURE DIRECTIONS

78       None.
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SEE ALSO

81       Scheduling Policies , pthread_getschedparam() ,  the  Base  Definitions
82       volume of IEEE Std 1003.1-2001, <pthread.h>
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85       Portions  of  this text are reprinted and reproduced in electronic form
86       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
87       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
88       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
89       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
90       event of any discrepancy between this version and the original IEEE and
91       The  Open Group Standard, the original IEEE and The Open Group Standard
92       is the referee document. The original Standard can be  obtained  online
93       at http://www.opengroup.org/unix/online.html .
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97IEEE/The Open Group                  2003              PTHREAD_SETSCHEDPRIO(P)
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