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Diffstat (limited to 'upstream/fedora-40/man3/clock.3')
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diff --git a/upstream/fedora-40/man3/clock.3 b/upstream/fedora-40/man3/clock.3 new file mode 100644 index 00000000..6d8ace49 --- /dev/null +++ b/upstream/fedora-40/man3/clock.3 @@ -0,0 +1,101 @@ +'\" t +.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de) +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" Modified Sat Jul 24 21:27:01 1993 by Rik Faith (faith@cs.unc.edu) +.\" 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 2023-10-31 "Linux man-pages 6.06" +.SH NAME +clock \- determine processor time +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <time.h> +.P +.B clock_t clock(void); +.fi +.SH DESCRIPTION +The +.BR clock () +function returns an approximation of processor time used by the program. +.SH RETURN VALUE +The value returned is the CPU time used so far as a +.IR clock_t ; +to get the number of seconds used, divide by +.BR CLOCKS_PER_SEC . +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; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR clock () +T} Thread safety MT-Safe +.TE +.SH VERSIONS +XSI requires that +.B CLOCKS_PER_SEC +equals 1000000 independent +of the actual resolution. +.P +On several other implementations, +the value returned by +.BR clock () +also includes the times of any children whose status has been +collected via +.BR wait (2) +(or another wait-type call). +Linux does not include the times of waited-for children in the +value returned by +.BR clock (). +.\" I have seen this behavior on Irix 6.3, and the OSF/1, HP/UX, and +.\" Solaris manual pages say that clock() also does this on those systems. +.\" POSIX.1-2001 doesn't explicitly allow this, nor is there an +.\" explicit prohibition. -- MTK +The +.BR times (2) +function, which explicitly returns (separate) information about the +caller and its children, may be preferable. +.SH STANDARDS +C11, POSIX.1-2008. +.SH HISTORY +POSIX.1-2001, C89. +.P +In glibc 2.17 and earlier, +.BR clock () +was implemented on top of +.BR times (2). +For improved accuracy, +since glibc 2.18, it is implemented on top of +.BR clock_gettime (2) +(using the +.B CLOCK_PROCESS_CPUTIME_ID +clock). +.SH NOTES +The C standard allows for arbitrary values at the start of the program; +subtract the value returned from a call to +.BR clock () +at the start of the program to get maximum portability. +.P +Note that the time can wrap around. +On a 32-bit system where +.B CLOCKS_PER_SEC +equals 1000000 this function will return the same +value approximately every 72 minutes. +.SH SEE ALSO +.BR clock_gettime (2), +.BR getrusage (2), +.BR times (2) |