man3/sched_getcpu.3

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   2 .\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
   3 .\"     <mtk.manpages@gmail.com>
   4 .\"
   5 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   6 .\"
   7 .TH sched_getcpu 3 (date) "Linux man-pages (unreleased)"
   8 .SH NAME
   9 sched_getcpu \- determine CPU on which the calling thread is running
  10 .SH LIBRARY
  11 Standard C library
  12 .RI ( libc ", " \-lc )
  13 .SH SYNOPSIS
  14 .nf
  15 .B #include <sched.h>
  16 .PP
  17 .B int sched_getcpu(void);
  18 .fi
  19 .PP
  20 .RS -4
  21 Feature Test Macro Requirements for glibc (see
  22 .BR feature_test_macros (7)):
  23 .RE
  24 .PP
  25 .BR sched_getcpu ():
  26 .nf
  27     Since glibc 2.14:
  28         _GNU_SOURCE
  29     Before glibc 2.14:
  30         _BSD_SOURCE || _SVID_SOURCE
  31             /* _GNU_SOURCE also suffices */
  32 .fi
  33 .SH DESCRIPTION
  34 .BR sched_getcpu ()
  35 returns the number of the CPU
  36 on which the calling thread is currently executing.
  37 .SH RETURN VALUE
  38 On success,
  39 .BR sched_getcpu ()
  40 returns a nonnegative CPU number.
  41 On error, \-1 is returned and
  42 .I errno
  43 is set to indicate the error.
  44 .SH ERRORS
  45 .TP
  46 .B ENOSYS
  47 This kernel does not implement
  48 .BR getcpu (2).
  49 .SH ATTRIBUTES
  50 For an explanation of the terms used in this section, see
  51 .BR attributes (7).
  52 .ad l
  53 .nh
  54 .TS
  55 allbox;
  56 lbx lb lb
  57 l l l.
  58 Interface       Attribute       Value
  59 T{
  60 .BR sched_getcpu ()
  61 T}      Thread safety   MT-Safe
  62 .TE
  63 .hy
  64 .ad
  65 .sp 1
  66 .SH STANDARDS
  67 GNU.
  68 .SH HISTORY
  69 glibc 2.6.
  70 .SH NOTES
  71 The call
  72 .PP
  73 .in +4n
  74 .EX
  75 cpu = sched_getcpu();
  76 .EE
  77 .in
  78 .PP
  79 is equivalent to the following
  80 .BR getcpu (2)
  81 call:
  82 .PP
  83 .in +4n
  84 .EX
  85 int c, s;
  86 s = getcpu(&c, NULL, NULL);
  87 cpu = (s == \-1) ? s : c;
  88 .EE
  89 .in
  90 .SH SEE ALSO
  91 .BR getcpu (2),
  92 .BR sched (7)