PROFIL(3)		   Linux Programmer's Manual		     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, profil-
       ing 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	inter-
       val timers (see setitimer(2)).

       True  kernel  profiling	provides more accurate results.	 Libc 4.4 con-
       tained 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 4.10 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/.



Linux				  2016-03-15			     PROFIL(3)