xref: /dragonfly/share/man/man9/microtime.9 (revision 106728aa)
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25.\"    $FreeBSD: src/share/man/man9/microtime.9,v 1.2.2.3 2001/12/17 11:30:18 ru Exp $
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27.Dd September 23, 2017
28.Dt MICROTIME 9
29.Os
30.Sh NAME
31.Nm microtime ,
32.Nm getmicrotime ,
33.Nm nanotime ,
34.Nm getnanotime
35.Nd get the current time
36.Sh SYNOPSIS
37.In sys/time.h
38.Ft void
39.Fn microtime "struct timeval *tv"
40.Ft void
41.Fn getmicrotime "struct timeval *tv"
42.Ft void
43.Fn nanotime "struct timespec *ts"
44.Ft void
45.Fn getnanotime "struct timespec *tsp"
46.Sh DESCRIPTION
47The
48.Fn microtime
49and
50.Fn getmicrotime
51functions stores the system time as a
52.Ft struct timeval
53at the address specified by
54.Fa tv .
55The
56.Fn nanotime
57and
58.Fn getnanotime
59functions perform the same utility, but record the time as a
60.Ft struct timespec
61instead.
62.Pp
63.Fn Microtime
64and
65.Fn nanotime
66always query the timecounter to return the current time as precisely as
67possible.
68Whereas
69.Fn getmicrotime
70and
71.Fn getnanotime
72functions are abstractions which return a less precise, but
73faster to obtain, time.
74The
75.Fn getmicrouptime
76and
77.Fn getnanouptime
78functions will return a time which is up to 1/HZ previous to the call.
79.Pp
80The intent of the
81.Fn getmicrotime
82and
83.Fn getnanotime
84functions is to enforce the user's preference for timer accuracy versus
85execution time.
86.Sh SEE ALSO
87.Xr getmicrouptime 9 ,
88.Xr getnanouptime 9 ,
89.Xr microuptime 9 ,
90.Xr nanouptime 9 ,
91.Xr tvtohz 9
92.Sh HISTORY
93The
94.Nm
95and
96.Nm nanotime
97functions first appeared in
98.Fx 3.0
99but existed in other incarnations since
100.Bx 4.4
101.Sh AUTHORS
102This manual page was written by
103.An Kelly Yancey Aq Mt kbyanc@posi.net .
104