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author | nik <nik@FreeBSD.org> | 2002-01-09 13:10:18 +0000 |
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committer | nik <nik@FreeBSD.org> | 2002-01-09 13:10:18 +0000 |
commit | b1e4a2fde15ab840a49ebd4487d4edb85c367749 (patch) | |
tree | 103b6edfa16f3af4f5ee0bc71bff025997832e48 /share/man/man7/clocks.7 | |
parent | 0fd45a70cfe8fea858bcad014427082c5c57f38d (diff) | |
download | FreeBSD-src-b1e4a2fde15ab840a49ebd4487d4edb85c367749.zip FreeBSD-src-b1e4a2fde15ab840a49ebd4487d4edb85c367749.tar.gz |
Fix typo, and add some additional description to the i8254 and TSC.
PR: docs/20738
Submitted by: Tan Koan-Sin <freedom@csie.nctu.edu.tw>
Diffstat (limited to 'share/man/man7/clocks.7')
-rw-r--r-- | share/man/man7/clocks.7 | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/share/man/man7/clocks.7 b/share/man/man7/clocks.7 index 018bbaa..5854273 100644 --- a/share/man/man7/clocks.7 +++ b/share/man/man7/clocks.7 @@ -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 |