1PROFIL(3)                  Linux Programmer's Manual                 PROFIL(3)
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NAME

6       profil - execution time profile
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SYNOPSIS

9       #include <unistd.h>
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11       int profil(unsigned short *buf, size_t bufsiz,
12                  size_t offset, unsigned int scale);
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14   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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16       profil():
17           Since glibc 2.21:
18               _DEFAULT_SOURCE
19           In glibc 2.19 and 2.20:
20               _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
21           Up to and including glibc 2.19:
22               _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
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DESCRIPTION

25       This  routine  provides  a means to find out in what areas your program
26       spends most of its time.  The argument buf points to  bufsiz  bytes  of
27       core.   Every  virtual 10 milliseconds, the user's program counter (PC)
28       is examined: offset is subtracted and the result is multiplied by scale
29       and divided by 65536.  If the resulting value is less than bufsiz, then
30       the corresponding entry in buf is incremented.  If buf is NULL, profil‐
31       ing is disabled.
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RETURN VALUE

34       Zero is always returned.
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ATTRIBUTES

37       For   an   explanation   of   the  terms  used  in  this  section,  see
38       attributes(7).
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40       ┌──────────┬───────────────┬───────────┐
41       │Interface │ Attribute     │ Value     │
42       ├──────────┼───────────────┼───────────┤
43       │profil()  │ Thread safety │ MT-Unsafe │
44       └──────────┴───────────────┴───────────┘
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CONFORMING TO

47       Similar to a call in SVr4 (but not POSIX.1).
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BUGS

50       profil() cannot be used on a program that also uses ITIMER_PROF  inter‐
51       val timers (see setitimer(2)).
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53       True  kernel  profiling  provides more accurate results.  Libc 4.4 con‐
54       tained a kernel patch providing a system call profil.
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SEE ALSO

57       gprof(1), sprof(1), setitimer(2), sigaction(2), signal(2)
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COLOPHON

60       This page is part of release 4.15 of the Linux  man-pages  project.   A
61       description  of  the project, information about reporting bugs, and the
62       latest    version    of    this    page,    can     be     found     at
63       https://www.kernel.org/doc/man-pages/.
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67Linux                             2017-09-15                         PROFIL(3)
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