man3/profil.3

   1 .\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
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  25 .\" Modified Fri Jun 23 01:35:19 1995 Andries Brouwer <aeb@cwi.nl>
  26 .\" (prompted by Bas V. de Bakker <bas@phys.uva.nl>)
  27 .\" Corrected (and moved to man3), 980612, aeb
  28 .TH PROFIL 3 2017-09-15 "Linux" "Linux Programmer's Manual"
  29 .SH NAME
  30 profil \- execution time profile
  31 .SH SYNOPSIS
  32 .nf
  33 .B #include <unistd.h>
  34 .PP
  35 .BI "int profil(unsigned short *" buf ", size_t " bufsiz ,
  36 .BI "           size_t " offset ", unsigned int " scale );
  37 .PP
  38 .fi
  39 .in -4n
  40 Feature Test Macro Requirements for glibc (see
  41 .BR feature_test_macros (7)):
  42 .in
  43 .PP
  44 .BR profil ():
  45 .nf
  46     Since glibc 2.21:
  47 .\"             commit 266865c0e7b79d4196e2cc393693463f03c90bd8
  48         _DEFAULT_SOURCE
  49     In glibc 2.19 and 2.20:
  50         _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
  51     Up to and including glibc 2.19:
  52         _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
  53 .fi
  54 .SH DESCRIPTION
  55 This routine provides a means to find out in what areas your program
  56 spends most of its time.
  57 The argument
  58 .I buf
  59 points to
  60 .I bufsiz
  61 bytes of core.
  62 Every virtual 10 milliseconds, the user's program counter (PC)
  63 is examined:
  64 .I offset
  65 is subtracted and the result is multiplied by
  66 .I scale
  67 and divided by 65536.
  68 If the resulting value is less than
  69 .IR bufsiz ,
  70 then the corresponding entry in
  71 .I buf
  72 is incremented.
  73 If
  74 .I buf
  75 is NULL, profiling is disabled.
  76 .SH RETURN VALUE
  77 Zero is always returned.
  78 .SH ATTRIBUTES
  79 For an explanation of the terms used in this section, see
  80 .BR attributes (7).
  81 .TS
  82 allbox;
  83 lb lb lb
  84 l l l.
  85 Interface       Attribute       Value
  86 T{
  87 .BR profil ()
  88 T}      Thread safety   MT-Unsafe
  89 .TE
  90 .sp 1
  91 .SH CONFORMING TO
  92 Similar to a call in SVr4 (but not POSIX.1).
  93 .SH BUGS
  94 .BR profil ()
  95 cannot be used on a program that also uses
  96 .B ITIMER_PROF
  97 interval timers (see
  98 .BR setitimer (2)).
  99 .PP
 100 True kernel profiling provides more accurate results.
 101 Libc 4.4 contained a kernel patch providing a system call profil.
 102 .SH SEE ALSO
 103 .BR gprof (1),
 104 .BR sprof (1),
 105 .BR setitimer (2),
 106 .BR sigaction (2),
 107 .BR signal (2)