mdoc(7) police: tidy up.
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@ -36,64 +36,71 @@
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.Sh SYNOPSIS
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.In time.h
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.Sh DESCRIPTION
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.Ql HZ
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.Dv HZ
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is not part of the application interface in
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.Bx .
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.Pp
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There are many different real and virtual (timekeeping) clocks with
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different frequencies:
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.Bl -bullet -offset XXX
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.Bl -bullet
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.It
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The scheduling clock. This is a real clock with frequency that
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happens to be 100. It isn't available to applications.
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The scheduling clock.
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This is a real clock with frequency that happens to be 100.
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It is not available to applications.
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.It
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The statistics clock. This is a real clock with frequency that
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happens to be 128. It isn't directly available to applications.
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The statistics clock.
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This is a real clock with frequency that happens to be 128.
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It is not directly available to applications.
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.It
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The clock reported by
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.Xr clock 3 .
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This is a virtual clock with a frequency that happens to be 128. Its
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actual frequency is given by the macro
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This is a virtual clock with a frequency that happens to be 128.
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Its actual frequency is given by the macro
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.Dv CLOCKS_PER_SEC .
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Note that
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.Dv CLOCKS_PER_SEC
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may be floating point. Don't use
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.Fn clock
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may be floating point.
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Do not use
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.Xr clock 3
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in new programs under
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.Fx .
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It is feeble compared with
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.Xr getrusage 2 .
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It is provided for ANSI conformance. It is implemented by calling
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.Fn getrusage
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It is provided for \*[Ai]
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conformance.
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It is implemented by calling
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.Xr getrusage 2
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and throwing away information and resolution.
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.It
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The clock reported by
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.Xr times 3 .
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This is a virtual clock with a frequency that happens to be 128. Its
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actual frequency is given by the macro
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This is a virtual clock with a frequency that happens to be 128.
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Its actual frequency is given by the macro
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.Dv CLK_TCK
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(deprecated; don't use) and by
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(deprecated; do not use) and by
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.Fn sysconf SC_CLK_TCK
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and by
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.Xr sysctl 3 .
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Note that its frequency may be different from
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.Dv CLOCKS_PER_SEC .
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Don't use
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Do not use
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.Xr times 3
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in new programs under
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.Fx .
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It is feeble compared with
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.Xr gettimeofday 2
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together with
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.Fn getrusage .
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It is provided for POSIX
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conformance. It is implemented by calling
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.Fn gettimeofday
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.Xr getrusage 2 .
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It is provided for \*[Px]
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conformance.
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It is implemented by calling
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.Xr gettimeofday 2
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and
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.Fn getrusage
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.Xr getrusage 2
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and throwing away information and resolution.
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.It
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The profiling clock. This is a real clock with frequency 1024.
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The profiling clock.
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This is a real clock with frequency 1024.
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It is used mainly by
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.Xr moncontrol 3 ,
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.Xr kgmon 8
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@ -103,43 +110,47 @@ Applications should determine its actual frequency using
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.Xr sysctl 3
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or by reading it from the header in the profiling data file.
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.It
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The mc146818a clock. This is a real clock with a nominal frequency of
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32768. It is divided down to give the statistic clock and the profiling
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clock. It isn't available to applications.
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The mc146818a clock.
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This is a real clock with a nominal frequency of 32768.
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It is divided down to give the statistic clock and the profiling clock.
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It is not available to applications.
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.It
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The microseconds clock. This is a virtual clock with frequency
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1000000. It is used for most timekeeping in
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The microseconds clock.
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This is a virtual clock with frequency 1000000.
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It is used for most timekeeping in
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.Bx
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and is exported
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to applications in
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and is exported to applications in
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.Xr getrusage 2 ,
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.Xr gettimeofday 2 ,
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.Xr select 2 ,
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.Xr getitimer 2 ,
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etc... This is the clock that should normally be used
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by
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etc.
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This is the clock that should normally be used by
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.Bx
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applications.
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.It
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The i8254 clock. This is a real clock/timer with a nominal frequency of
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1193182. It has three independent time counters to be used.
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It is divided down to give the scheduling clock. It isn't
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available to applications.
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The i8254 clock.
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This is a real clock/timer with a nominal frequency of 1193182.
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It has three independent time counters to be used.
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It is divided down to give the scheduling clock.
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It is not available to applications.
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.It
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The TSC clock (64-bit register) on fifth-generation or later x86 systems.
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This is a real clock with a frequency that is equivalent to the number of
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cycles per second of the CPU(s).
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Its frequency can be found using the sysctl
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.Sy machdep.tsc_freq ,
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if it is available.
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Its frequency can be found using the
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.Va machdep.tsc_freq
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sysctl, if it is available.
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It is used to interpolate between values of the scheduling clock.
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It can be accessed using the PMIOTSTAMP request of
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It can be accessed using the
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.Dv PMIOTSTAMP
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request of
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.Xr perfmon 4 .
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.El
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.Pp
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Summary: if
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.Ql HZ
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isn't 1000000 then the application is probably using the wrong clock.
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.Dv HZ
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is not 1000000 then the application is probably using the wrong clock.
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.Sh SEE ALSO
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.Xr gprof 1 ,
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.Xr getitimer 2 ,
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