man3/profil.3

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   3 .\" 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 1993-07-23 "Linux 2.0" "Linux Programmer's Manual"
  29 .SH NAME
  30 profil \- execution time profile
  31 .SH SYNOPSIS
  32 .B #include <unistd.h>
  33 .sp
  34 .BI "int profil(u_short *" buf ", size_t " bufsiz ", size_t " offset ", u_int " scale );
  35 .SH DESCRIPTION
  36 This routine provides a means to find out in what areas your program
  37 spends most of its time. The argument
  38 .I buf
  39 points to
  40 .I bufsiz
  41 bytes of core.  Every virtual 10 milliseconds, the user's program counter (PC)
  42 is examined:
  43 .I offset
  44 is subtracted and the result is multiplied by
  45 .IR scale
  46 and divided by 65536.
  47 If the resulting value is less than
  48 .IR bufsiz ,
  49 then the corresponding entry in
  50 .I buf
  51 is incremented.
  52 If
  53 .I buf
  54 is NULL, profiling is disabled.
  55 .SH "RETURN VALUE"
  56 Zero is always returned.
  57 .SH BUGS
  58 .B profil
  59 cannot be used on a program that also uses
  60 .B ITIMER_PROF
  61 itimers.
  62
  63 True kernel profiling provides more accurate results.
  64 Libc 4.4 contained a kernel patch providing a system call profil.
  65 .SH "CONFORMING TO"
  66 Similar to a call in SVr4 (but not POSIX.1).
  67 .SH "SEE ALSO"
  68 .BR gprof (1),
  69 .BR setitimer (2),
  70 .BR sigaction (2),
  71 .BR signal (2)