tickadj



tickadj(1)                                                          tickadj(1)




NAME

       tickadj - set time-related kernel variables


SYNOPSIS

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


DESCRIPTION

       The  tickadj  program reads, and optionally modifies, several timekeep-
       ing-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 sys-
       tem 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   speci-
               fied.

       -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 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

       Primary source of documentation: /usr/share/doc/ntp-*/tickadj.html



AUTHOR

       David L. Mills <mills@udel.edu>



ntp 4.1.1b-r5                                                       tickadj(1)

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