.\" Modified 14 Jun 2002, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Added notes on differences from other UNIX systems with respect to
.\" waited-for children.
-.TH CLOCK 3 2015-03-29 "GNU" "Linux Programmer's Manual"
+.TH CLOCK 3 2017-09-15 "GNU" "Linux Programmer's Manual"
.SH NAME
clock \- determine processor time
.SH SYNOPSIS
.nf
.B #include <time.h>
-.sp
+.PP
.B clock_t clock(void);
.fi
.SH DESCRIPTION
If the processor time used is not available or its value cannot
be represented, the function returns the value
.IR (clock_t)\ \-1 .
+.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 clock ()
+T} Thread safety MT-Safe
+.TE
+.sp 1
.SH CONFORMING TO
-C89, C99, POSIX.1-2001.
+POSIX.1-2001, POSIX.1-2008, C89, C99.
XSI requires that
.B CLOCKS_PER_SEC
equals 1000000 independent
.BR times (2)
function, which explicitly returns (separate) information about the
caller and its children, may be preferable.
-
+.PP
In glibc 2.17 and earlier,
.BR clock ()
was implemented on top of