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Fix typo, and add some additional description to the i8254 and TSC.

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PR:		docs/20738
Submitted by:	Tan Koan-Sin <freedom@csie.nctu.edu.tw>
This commit is contained in:
Nik Clayton 2002-01-09 13:10:18 +00:00
parent befb729958
commit e67796ea42
1 changed files with 7 additions and 4 deletions
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11
share/man/man7/clocks.7
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@ -103,7 +103,7 @@ Applications should determine its actual frequency using
.Xr sysctl 3
or by reading it from the header in the profiling data file.
.It
The mc14618a clock. This is a real clock with a nominal frequency of
The mc146818a clock. This is a real clock with a nominal frequency of
32768. It is divided down to give the statistic clock and the profiling
clock. It isn't available to applications.
.It
@ -122,16 +122,19 @@ by
applications.
.It
The i8254 clock. This is a real clock/timer with a nominal frequency of
1193182. It is divided down to give the scheduling clock. It isn't
1193182. It has three independent time counters to be used.
It is divided down to give the scheduling clock. It isn't
available to applications.
.It
The TSC clock (64-bit register) on fifth-generation or later x86 systems.
This is a real clock with a frequency that is equivalent to the number of
cycles per second of the CPU(s).
Its frequency can be found using the sysctl
.Sy machdep.tsc_freq .
.Sy machdep.tsc_freq ,
if it is available.
It is used to interpolate between values of the scheduling clock.
It is only available to applications in a purely machine-dependent manner.
It can be accessed using the PMIOTSTAMP request of
.Xr perfmon 4 .
.El
.Pp
Summary: if