54 lines
1.5 KiB
Plaintext
54 lines
1.5 KiB
Plaintext
'\"macro stdmacro
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.if n .pH g3c.clock @(#)clock 30.2 of 12/25/85
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.nr X
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.if \nX=0 .ds x} CLOCK 3C "C Programming Language Utilities" "\&"
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.if \nX=1 .ds x} CLOCK 3C "C Programming Language Utilities"
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.if \nX=2 .ds x} CLOCK 3C "" "\&"
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.if \nX=3 .ds x} CLOCK "" "" "\&"
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.TH \*(x}
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.SH NAME
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clock \- report CPU time used
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.SH SYNOPSIS
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.B #include <time.h>
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.PP
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.B clock_t clock (void);
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.SH DESCRIPTION
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.I clock\^
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returns the amount of CPU time used since the
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first call to
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.IR clock .
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The unit time of clock (microseconds) is indicated in
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the macro CLOCKS_PER_SEC found
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in the file
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.IR <time.h> .
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The time reported is the sum of the user and system times of the
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calling process and its terminated child processes for which it has executed
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.IR wait (2),
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.IR pclose (3S),
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or
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.IR system (3S).
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.PP
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The resolution of the clock is 10 milliseconds on IRIS workstations.
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.SH SEE ALSO
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times(2), wait(2), popen(3S), system(3S).
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.SH BUGS
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The implementation of
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.I clock\^
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conflicts with the definition of the routine found in
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the ANSI C Standard. The discrepancy will be transparent, however,
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so long as programs which adhere to that Standard use
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the difference in two invocations of
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.I clock\^
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for timing information, as recommended by the Standard.
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.PP
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The value returned by
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.I clock\^
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is defined in microseconds for compatibility with systems that have
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CPU clocks with much higher resolution.
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Because of this, the value returned
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will wrap around after accumulating
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only 2147 seconds of CPU time (about 36 minutes).
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'\".so /pubs/tools/origin.att
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.\" @(#)clock.3c 6.2 of 10/20/83
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.Ee
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