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144 lines
3.3 KiB
Groff
144 lines
3.3 KiB
Groff
''' $Header
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'''
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.de Sh
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.br
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'''
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''' Set up \*(-- to give an unbreakable dash;
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''' string Tr holds user defined translation string.
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''' Greek uppercase omega is used as a dummy character.
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'''
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.tr \(*W-|\(bv\*(Tr
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.ie n \{\
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.ds -- \(*W-
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.if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
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.if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
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.ds L" ""
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'br\}
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.ds -- \(em\|
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.tr \*(Tr
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.ds L" ``
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'br\}
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.TH TICKADJ 8 LOCAL
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.SH NAME
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tickadj - fiddle time\-related variables in the kernel
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.SH SYNOPSIS
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.B tickadj
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[
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.B -Aqs
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] [
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.B -a
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.I new_tickadj
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] [
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.B -t
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.I new_tick
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]
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.SH DESCRIPTION
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The
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.I tickadj
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program reads, and optionally modifies, several time\-keeping\-related
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variables in the running kernel, via
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.IR /dev/kmem .
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The particular variables it is concerned with are
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.IR tick ,
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which is the number of microseconds added to the system time during a
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clock interrupt,
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.IR tickadj ,
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which sets the slew rate and resolution used by the
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.IR adjtime (2)
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system call, and
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.IR dosynctodr ,
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which indicates to the kernels on some machines whether they should internally
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adjust the system clock to keep it in line with with time\-of\-day clock
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or not.
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.PP
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By default, with no arguments,
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.I tickadj
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reads the variables of interest in the kernel and prints them. At the
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same time it determines an \*(L"optimal\*(R" value for the value of the
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.I tickadj
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variable if the intent is to run the
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.IR xntpd (8)
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Network Time Protocol daemon, and prints this as well. Since the operation
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of
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.I tickadj
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when reading the kernel mimics the operation of similar parts of the
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.IR xntpd (8)
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program fairly closely, this is useful for doing debugging of problems
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with
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.IR xntpd (8).
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.PP
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Various flags may be specified to change the variables of interest in
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the running kernel. The
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.B -a
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flag allows one to set the the variable
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.I tickadj
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to the value specified as an argument. The
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.B -A
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flag will also cause
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.I tickadj
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to be modified, but instead will set it to the internally computed
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\*(L"optimal\*(R" value. The
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.B -t
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flag may be used to reset the kernel's value of
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.IR tick ,
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a capability which is useful on machines with very broken clocks. The
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.B -s
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flag tells the program to set the value of the variable
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.I dosynctodr
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to zero, a prerequisite for running the
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.IR xntpd (8)
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daemon under SunOS 4.0. Normally
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.I tickadj
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is quite verbose about what it is doing. The
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.B -q
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flag tells it to shut up about everything except errors.
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.PP
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Note that
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.I tickadj
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should be run with some caution when being used for the first time on
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different types of machines. The operations which
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.I tickadj
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trys to perform are not guaranteed to work on all Unix machines.
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.SH FILES
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.nf
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/vmunix
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/unix
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/dev/kmem
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.fi
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.SH SEE ALSO
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xntpd(8)
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.SH HISTORY
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Written by Dennis Ferguson at the University of Toronto
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.SH BUGS
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Fiddling with kernel variables at run time as a part of ordinary
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operations is a hideous practice which is only necessary to make
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up for deficiencies in the implementation of
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.IR adjtime (8)
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in many kernels and/or brokenness of the system clock in some
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vendors' kernels. It would be much better if the kernels were fixed
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and the
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.I tickadj
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program went away.
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