dlinfo.3: ATTRIBUTES: Note function that is thread-safe

[thirdparty/man-pages.git] / man3 / profil.3

.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.\" 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 2015-07-23 "Linux" "Linux Programmer's Manual"
.SH NAME
profil \- execution time profile
.SH SYNOPSIS
.nf
.B #include <unistd.h>
.sp
.BI "int profil(unsigned short *" buf ", size_t " bufsiz ,
.BI "           size_t " offset ", unsigned int " scale );
.sp
.fi
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.BR profil ():
_BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
.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
.I 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 ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.BR profil ()
T}	Thread safety	MT-Unsafe
.TE

.SH CONFORMING TO
Similar to a call in SVr4 (but not POSIX.1).
.SH BUGS
.BR profil ()
cannot be used on a program that also uses
.B ITIMER_PROF
interval timers (see
.BR setitimer (2)).

True kernel profiling provides more accurate results.
Libc 4.4 contained a kernel patch providing a system call profil.
.SH SEE ALSO
.BR gprof (1),
.BR sprof (1),
.BR setitimer (2),
.BR sigaction (2),
.BR signal (2)