profil(3)

NAME

   profil - execution time profile

SYNOPSIS

   #include <unistd.h>

   int profil(unsigned short *buf, size_t bufsiz,
              size_t offset, unsigned int scale);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

   profil():
       Since glibc 2.21:
           _DEFAULT_SOURCE
       In glibc 2.19 and 2.20:
           _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
       Up to and including glibc 2.19:
           _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)

DESCRIPTION

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

RETURN VALUE

   Zero is always returned.

ATTRIBUTES

   For   an   explanation   of   the  terms  used  in  this  section,  see
   attributes(7).

   
   Interface  Attribute      Value     
   
   profil()   Thread safety  MT-Unsafe 
   

CONFORMING TO

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

BUGS

   profil() cannot be  used  on  a  program  that  also  uses  ITIMER_PROF
   interval timers (see setitimer(2)).

   True  kernel  profiling  provides  more  accurate  results.   Libc  4.4
   contained a kernel patch providing a system call profil.

SEE ALSO

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

COLOPHON

   This page is part of release 4.09 of the Linux  man-pages  project.   A
   description  of  the project, information about reporting bugs, and the
   latest    version    of    this    page,    can     be     found     at
   https://www.kernel.org/doc/man-pages/.

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