man2/sched_setparam.2

   1 .\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
   2 .\"
   3 .\" SPDX-License-Identifier: GPL-2.0-or-later
   4 .\"
   5 .\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
   6 .\"            First version written
   7 .\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
   8 .\"            revision
   9 .\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
  10 .\"
  11 .TH SCHED_SETPARAM 2 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
  12 .SH NAME
  13 sched_setparam, sched_getparam \- set and get scheduling parameters
  14 .SH LIBRARY
  15 Standard C library
  16 .RI ( libc ", " \-lc )
  17 .SH SYNOPSIS
  18 .nf
  19 .B #include <sched.h>
  20 .PP
  21 .BI "int sched_setparam(pid_t " pid ", const struct sched_param *" param );
  22 .BI "int sched_getparam(pid_t " pid ", struct sched_param *" param );
  23 .PP
  24 \fBstruct sched_param {
  25     ...
  26     int \fIsched_priority\fB;
  27     ...
  28 };
  29 .fi
  30 .SH DESCRIPTION
  31 .BR sched_setparam ()
  32 sets the scheduling parameters associated with the scheduling policy
  33 for the thread whose thread ID is specified in \fIpid\fP.
  34 If \fIpid\fP is zero, then
  35 the parameters of the calling thread are set.
  36 The interpretation of
  37 the argument \fIparam\fP depends on the scheduling
  38 policy of the thread identified by
  39 .IR pid .
  40 See
  41 .BR sched (7)
  42 for a description of the scheduling policies supported under Linux.
  43 .PP
  44 .BR sched_getparam ()
  45 retrieves the scheduling parameters for the
  46 thread identified by \fIpid\fP.
  47 If \fIpid\fP is zero, then the parameters
  48 of the calling thread are retrieved.
  49 .PP
  50 .BR sched_setparam ()
  51 checks the validity of \fIparam\fP for the scheduling policy of the
  52 thread.
  53 The value \fIparam\->sched_priority\fP must lie within the
  54 range given by
  55 .BR sched_get_priority_min (2)
  56 and
  57 .BR sched_get_priority_max (2).
  58 .PP
  59 For a discussion of the privileges and resource limits related to
  60 scheduling priority and policy, see
  61 .BR sched (7).
  62 .PP
  63 POSIX systems on which
  64 .BR sched_setparam ()
  65 and
  66 .BR sched_getparam ()
  67 are available define
  68 .B _POSIX_PRIORITY_SCHEDULING
  69 in \fI<unistd.h>\fP.
  70 .SH RETURN VALUE
  71 On success,
  72 .BR sched_setparam ()
  73 and
  74 .BR sched_getparam ()
  75 return 0.
  76 On error, \-1 is returned, and
  77 .I errno
  78 is set to indicate the error.
  79 .SH ERRORS
  80 .TP
  81 .B EINVAL
  82 Invalid arguments:
  83 .I param
  84 is NULL or
  85 .I pid
  86 is negative
  87 .TP
  88 .B EINVAL
  89 .RB ( sched_setparam ())
  90 The argument \fIparam\fP does not make sense for the current
  91 scheduling policy.
  92 .TP
  93 .B EPERM
  94 .RB ( sched_setparam ())
  95 The caller does not have appropriate privileges
  96 (Linux: does not have the
  97 .B CAP_SYS_NICE
  98 capability).
  99 .TP
 100 .B ESRCH
 101 The thread whose ID is \fIpid\fP could not be found.
 102 .SH STANDARDS
 103 POSIX.1-2001, POSIX.1-2008.
 104 .SH SEE ALSO
 105 .ad l
 106 .nh
 107 .BR getpriority (2),
 108 .BR gettid (2),
 109 .BR nice (2),
 110 .BR sched_get_priority_max (2),
 111 .BR sched_get_priority_min (2),
 112 .BR sched_getaffinity (2),
 113 .BR sched_getscheduler (2),
 114 .BR sched_setaffinity (2),
 115 .BR sched_setattr (2),
 116 .BR sched_setscheduler (2),
 117 .BR setpriority (2),
 118 .BR capabilities (7),
 119 .BR sched (7)