NAME
tickadj - set time-related kernel variables
SYNOPSIS
tickadj [ -Aqs ] [ -a tickadj ] [ -t tick ]
DESCRIPTION
The tickadj program reads, and
optionally modifies, several timekeeping-related variables in the
running kernel in some machines, via /dev/kmem . The
particular variables it is concerned with are tick , which
is the number of microseconds added to the system time during a
clock interrupt, tickadj , which sets the slew rate and
resolution used by the adjtime system call, and
dosynctodr , which indicates to the kernels on some machines
whether they should internally adjust the system clock to keep it
in line with time-of-day clock or not.
By default, with no arguments, tickadj reads the
variables of interest in the kernel and displays them. At the same
time, it determines an "optimal" value for the value of the
tickadj variable if the intent is to run the ntpd
Network Time Protocol (NTP) daemon, and prints this as well. Since
the operation of tickadj when reading the kernel mimics the
operation of similar parts of the ntpd program fairly
closely, this can be useful when debugging problems with
ntpd .
Note that tickadj should be run with some caution when
being used for the first time on different types of machines. The
operations which tickadj tries to perform are not guaranteed
to work on all Unix machines and may in rare cases cause the kernel
to crash.
COMMAND LINE OPTIONS
- -a
- tickadj Set the kernel variable tickadj to the
value tickadj specified.
- -A
- Set the kernel variable tickadj to an internally
computed "optimal" value.
- -t
- tick Set the kernel variable tick to the value
tick specified.
- -s
- Set the kernel variable dosynctodr to zero, which
disables the hardware time-of-year clock, a prerequisite for
running the ntpd daemon under SunOS4.
- -q
- Normally, tickadj is quite verbose about what it is
doing. The -q flag tells it to shut up about everything
except errors.
FILES
/vmunix
/unix
/dev/kmem
BUGS
Fiddling with kernel variables at run time as a part
of ordinary operations is a hideous practice which is only
necessary to make up for deficiencies in the implementation of
adjtime in many kernels and/or brokenness of the system
clock in some vendors' kernels. It would be much better if the
kernels were fixed and the tickadj program went
away.Â
SEE ALSO
Primary source of documentation:
/usr/share/doc/ntp-*/tickadj.html
AUTHOR
David L. Mills <mills@udel.edu>