man3/pthread_attr_setschedparam.3

   1 .\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
   2 .\"     <mtk.manpages@gmail.com>
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .\"
   6 .TH PTHREAD_ATTR_SETSCHEDPARAM 3 2021-03-22 "Linux" "Linux Programmer's Manual"
   7 .SH NAME
   8 pthread_attr_setschedparam, pthread_attr_getschedparam \- set/get
   9 scheduling parameter attributes in thread attributes object
  10 .SH LIBRARY
  11 POSIX threads library
  12 .RI ( libpthread ", " \-lpthread )
  13 .SH SYNOPSIS
  14 .nf
  15 .B #include <pthread.h>
  16 .PP
  17 .BI "int pthread_attr_setschedparam(pthread_attr_t *restrict " attr ,
  18 .BI "                              const struct sched_param *restrict " param );
  19 .BI "int pthread_attr_getschedparam(const pthread_attr_t *restrict " attr ,
  20 .BI "                              struct sched_param *restrict " param );
  21 .fi
  22 .SH DESCRIPTION
  23 The
  24 .BR pthread_attr_setschedparam ()
  25 function sets the scheduling parameter attributes of the
  26 thread attributes object referred to by
  27 .IR attr
  28 to the values specified in the buffer pointed to by
  29 .IR param .
  30 These attributes determine the scheduling parameters of
  31 a thread created using the thread attributes object
  32 .IR attr .
  33 .PP
  34 The
  35 .BR pthread_attr_getschedparam ()
  36 returns the scheduling parameter attributes of the thread attributes object
  37 .IR attr
  38 in the buffer pointed to by
  39 .IR param .
  40 .PP
  41 Scheduling parameters are maintained in the following structure:
  42 .PP
  43 .in +4n
  44 .EX
  45 struct sched_param {
  46     int sched_priority;     /* Scheduling priority */
  47 };
  48 .EE
  49 .in
  50 .PP
  51 As can be seen, only one scheduling parameter is supported.
  52 For details of the permitted ranges for scheduling priorities
  53 in each scheduling policy, see
  54 .BR sched (7).
  55 .PP
  56 In order for the parameter setting made by
  57 .BR pthread_attr_setschedparam ()
  58 to have effect when calling
  59 .BR pthread_create (3),
  60 the caller must use
  61 .BR pthread_attr_setinheritsched (3)
  62 to set the inherit-scheduler attribute of the attributes object
  63 .I attr
  64 to
  65 .BR PTHREAD_EXPLICIT_SCHED .
  66 .SH RETURN VALUE
  67 On success, these functions return 0;
  68 on error, they return a nonzero error number.
  69 .SH ERRORS
  70 .BR pthread_attr_setschedparam ()
  71 can fail with the following error:
  72 .TP
  73 .B EINVAL
  74 The priority specified in
  75 .I param
  76 does not make sense for the current scheduling policy of
  77 .IR attr .
  78 .PP
  79 POSIX.1 also documents an
  80 .B ENOTSUP
  81 error for
  82 .BR pthread_attr_setschedparam ().
  83 This value is never returned on Linux
  84 (but portable and future-proof applications should nevertheless
  85 handle this error return value).
  86 .\" .SH VERSIONS
  87 .\" Available since glibc 2.0.
  88 .SH ATTRIBUTES
  89 For an explanation of the terms used in this section, see
  90 .BR attributes (7).
  91 .ad l
  92 .nh
  93 .TS
  94 allbox;
  95 lbx lb lb
  96 l l l.
  97 Interface       Attribute       Value
  98 T{
  99 .BR pthread_attr_setschedparam (),
 100 .BR pthread_attr_getschedparam ()
 101 T}      Thread safety   MT-Safe
 102 .TE
 103 .hy
 104 .ad
 105 .sp 1
 106 .SH CONFORMING TO
 107 POSIX.1-2001, POSIX.1-2008.
 108 .SH NOTES
 109 See
 110 .BR pthread_attr_setschedpolicy (3)
 111 for a list of the thread scheduling policies supported on Linux.
 112 .SH EXAMPLES
 113 See
 114 .BR pthread_setschedparam (3).
 115 .SH SEE ALSO
 116 .ad l
 117 .nh
 118 .BR sched_get_priority_min (2),
 119 .BR pthread_attr_init (3),
 120 .BR pthread_attr_setinheritsched (3),
 121 .BR pthread_attr_setschedpolicy (3),
 122 .BR pthread_create (3),
 123 .BR pthread_setschedparam (3),
 124 .BR pthread_setschedprio (3),
 125 .BR pthreads (7),
 126 .BR sched (7)