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tickadj(8)                  System Manager's Manual                 tickadj(8)

NAME
       tickadj - set time-related kernel variables

SYNOPSIS
       tickadj [ tick ]
       tickadj [ -Aqs ] [ -a tickadj ] [ -t tick ]

DESCRIPTION
       The  tickadj  program reads, and optionally modifies, several timekeep-
       ing-related variables in older kernels that do  not  have  support  for
       precision  ttimekeeping, including HP-UX, SunOS, Ultrix, SGI and proba-
       bly others. Those machines provide means to patch the kernel /dev/kmem.
       Newer  machines  with  kernel  time  support, including Solaris, Tru64,
       FreeBSD and Linux, should NOT use the program, even if  it  appears  to
       work,  as  it will destabilize the kernel time support. Use the ntptime
       program instead.
       The particular variables that can be changed with tickadj include tick,
       which  is  the  number  of  microseconds added to the system time for a
       clock interrupt, tickadj, which sets the slew rate and resolution  used
       by the adjtime system call, and dosynctodr, which indicates to the ker-
       nels on some machines whether they should internally adjust the  system
       clock to keep it in line with time-of-day clock or not.
       On  Linux,  only  the  tick  variable is supported and the only allowed
       argument is the tick value.
       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 tickadjspecified.
       -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 SunOS 4.x.
       -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 opera-
       tions 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.
SEE ALSO
       ntpd(8)
       The official HTML documentation.
       This file was automatically generated from HTML source.


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