xref: /minix3/lib/libc/gen/times.3 (revision 2fe8fb192fe7e8720e3e7a77f928da545e872a6a)
1.\"	$NetBSD: times.3,v 1.15 2003/08/07 16:42:58 agc Exp $
2.\"
3.\" Copyright (c) 1990, 1991, 1993
4.\"	The Regents of the University of California.  All rights reserved.
5.\"
6.\" Redistribution and use in source and binary forms, with or without
7.\" modification, are permitted provided that the following conditions
8.\" are met:
9.\" 1. Redistributions of source code must retain the above copyright
10.\"    notice, this list of conditions and the following disclaimer.
11.\" 2. Redistributions in binary form must reproduce the above copyright
12.\"    notice, this list of conditions and the following disclaimer in the
13.\"    documentation and/or other materials provided with the distribution.
14.\" 3. Neither the name of the University nor the names of its contributors
15.\"    may be used to endorse or promote products derived from this software
16.\"    without specific prior written permission.
17.\"
18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28.\" SUCH DAMAGE.
29.\"
30.\"     @(#)times.3	8.1 (Berkeley) 6/4/93
31.\"
32.Dd June 4, 1993
33.Dt TIMES 3
34.Os
35.Sh NAME
36.Nm times
37.Nd process times
38.Sh LIBRARY
39.Lb libc
40.Sh SYNOPSIS
41.In sys/times.h
42.Ft clock_t
43.Fn times "struct tms *tp"
44.Sh DESCRIPTION
45.Bf -symbolic
46This interface is obsoleted by
47.Xr getrusage 2
48and
49.Xr gettimeofday 2 .
50.Ef
51.Pp
52The
53.Fn times
54function returns the value of time in clock ticks since 0 hours, 0
55minutes, 0 seconds, January 1, 1970, Coordinated Universal Time (UTC).
56.Pp
57The number of clock ticks per second may be determined by calling
58.Xr sysconf 3
59with the
60.Dv _SC_CLK_TCK
61request.
62It is generally (but not always) between 60 and 1024.
63.Pp
64Note that at the common rate of 100 ticks per second on many
65.Nx
66ports, and with a 32-bit unsigned clock_t, this value first wrapped in 1971.
67.Pp
68The
69.Fn times
70call also fills in the structure pointed to by
71.Fa tp
72with time-accounting information.
73.Pp
74The
75.Fa tms
76structure is defined as follows:
77.Bd -literal -offset indent
78typedef struct {
79	clock_t tms_utime;
80	clock_t tms_stime;
81	clock_t tms_cutime;
82	clock_t tms_cstime;
83}
84.Ed
85.Pp
86The elements of this structure are defined as follows:
87.Bl -tag -width tms_cutime
88.It Fa tms_utime
89The
90.Tn CPU
91time charged for the execution of user instructions.
92.It Fa tms_stime
93The
94.Tn CPU
95time charged for execution by the system on behalf of
96the process.
97.It Fa tms_cutime
98The sum of the
99.Fa tms_utime  s
100and
101.Fa tms_cutime  s
102of the child processes.
103.It Fa tms_cstime
104The sum of the
105.Fa tms_stime Ns s
106and
107.Fa tms_cstime Ns s
108of the child processes.
109.El
110.Pp
111All times are measured in clock ticks, as defined above.
112Note that at 100 ticks per second,
113and with a 32-bit unsigned clock_t,
114the values wrap after 497 days.
115.Pp
116The times of a terminated child process are included in the
117.Fa tms_cutime
118and
119.Fa tms_cstime
120elements of the parent when one of the
121.Xr wait 2
122functions returns the process ID of the terminated child to the parent.
123If an error occurs,
124.Fn times
125returns the value
126.Pq (clock_t)\-1 ,
127and sets
128.Va errno
129to indicate the error.
130.Sh ERRORS
131The
132.Fn times
133function
134may fail and set the global variable
135.Va errno
136for any of the errors specified for the library
137routines
138.Xr getrusage 2
139and
140.Xr gettimeofday 2 .
141.Sh SEE ALSO
142.Xr time 1 ,
143.Xr getrusage 2 ,
144.Xr gettimeofday 2 ,
145.Xr wait 2 ,
146.Xr sysconf 3
147.Sh STANDARDS
148The
149.Fn times
150function conforms to
151.St -p1003.1-90 .
152