freebsd-nq/lib/libc/gen/clock.3
David Malone 7e1b81799d Add a note explaining why CLOCKS_PER_SEC isn't 1000000.
While I'm here, "of a second" does not belong to CLOCKS_PER_SEC.

PR:		30297
Submitted by:	Bernd Luevelsmeyer <bdluevel@heitec.net>
2001-11-05 21:30:43 +00:00

81 lines
2.8 KiB
Groff

.\" Copyright (c) 1990, 1991, 1993
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.\" @(#)clock.3 8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dt CLOCK 3
.Os
.Sh NAME
.Nm clock
.Nd determine processor time used
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In time.h
.Ft clock_t
.Fn clock void
.Sh DESCRIPTION
The
.Fn clock
function
determines the amount of processor time used since the invocation of the
calling process, measured in
.Dv CLOCKS_PER_SEC Ns s
of a second.
.Sh RETURN VALUES
The
.Fn clock
function returns the amount of time used unless an error occurs, in which
case the return value is \-1.
.Sh SEE ALSO
.Xr getrusage 2 ,
.Xr clocks 7
.Sh STANDARDS
The
.Fn clock
function conforms to
.St -isoC .
However,
.St -susv2
requires
.Dv CLOCKS_PER_SEC
to be defined as one million.
.Fx
does not conform to this requirement;
changing the value would introduce binary incompatibility
and one million is still inadequate on modern processors.