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.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
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.\" Modified Fri Jun 23 01:35:19 1995 Andries Brouwer <aeb@cwi.nl>
.\" (prompted by Bas V. de Bakker <bas@phys.uva.nl>)
.\" Corrected (and moved to man3), 980612, aeb
.TH PROFIL 3 "23 July 1993" "Linux 2.0" "Linux Programmer's Manual"
.SH NAME
profil \- execution time profile
.SH SYNOPSIS
.B #include <unistd.h>
.sp
.BI "int profil(u_short *" buf ", size_t " bufsiz ", size_t " offset ", u_int " scale );
.SH DESCRIPTION
This routine provides a means to find out in what areas your program
spends most of its time. The argument
.I buf
points to
.I bufsiz
bytes of core.  Every virtual 10 milliseconds, the user's program counter (PC)
is examined:
.I offset
is subtracted and the result is multiplied by
.IR scale
and divided by 65536.
If the resulting value is less than
.IR bufsiz ,
then the corresponding entry in
.I buf
is incremented.
If
.I buf
is NULL, profiling is disabled.
.SH "RETURN VALUE"
Zero is always returned.
.SH BUGS
.B profil
cannot be used on a program that also uses
.B ITIMER_PROF
itimers.

True kernel profiling provides more accurate results.
Libc 4.4 contained a kernel patch providing a system call profil.
.SH "CONFORMING TO"
Similar to a call in SVr4 (but not POSIX.1).
.SH "SEE ALSO"
.BR gprof "(1), " setitimer "(2), " signal "(2), " sigaction (2)