xref: /freebsd/lib/libc/gen/clock.3 (revision a220d00e74dd245b4fca59c5eca0c53963686325)
1.\" Copyright (c) 1990, 1991, 1993
2.\"	The Regents of the University of California.  All rights reserved.
3.\"
4.\" This code is derived from software contributed to Berkeley by
5.\" the American National Standards Committee X3, on Information
6.\" Processing Systems.
7.\"
8.\" Redistribution and use in source and binary forms, with or without
9.\" modification, are permitted provided that the following conditions
10.\" are met:
11.\" 1. Redistributions of source code must retain the above copyright
12.\"    notice, this list of conditions and the following disclaimer.
13.\" 2. Redistributions in binary form must reproduce the above copyright
14.\"    notice, this list of conditions and the following disclaimer in the
15.\"    documentation and/or other materials provided with the distribution.
16.\" 3. All advertising materials mentioning features or use of this software
17.\"    must display the following acknowledgement:
18.\"	This product includes software developed by the University of
19.\"	California, Berkeley and its contributors.
20.\" 4. Neither the name of the University nor the names of its contributors
21.\"    may be used to endorse or promote products derived from this software
22.\"    without specific prior written permission.
23.\"
24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34.\" SUCH DAMAGE.
35.\"
36.\"     @(#)clock.3	8.1 (Berkeley) 6/4/93
37.\" $FreeBSD$
38.\"
39.Dd June 4, 1993
40.Dt CLOCK 3
41.Os
42.Sh NAME
43.Nm clock
44.Nd determine processor time used
45.Sh LIBRARY
46.Lb libc
47.Sh SYNOPSIS
48.In time.h
49.Ft clock_t
50.Fn clock void
51.Sh DESCRIPTION
52The
53.Fn clock
54function
55determines the amount of processor time used since the invocation of the
56calling process, measured in
57.Dv CLOCKS_PER_SEC Ns s
58of a second.
59.Sh RETURN VALUES
60The
61.Fn clock
62function returns the amount of time used unless an error occurs, in which
63case the return value is \-1.
64.Sh SEE ALSO
65.Xr getrusage 2 ,
66.Xr clocks 7
67.Sh STANDARDS
68The
69.Fn clock
70function conforms to
71.St -isoC .
72However,
73.St -susv2
74requires
75.Dv CLOCKS_PER_SEC
76to be defined as one million.
77.Fx
78does not conform to this requirement;
79changing the value would introduce binary incompatibility
80and one million is still inadequate on modern processors.
81