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
       system clock to keep it in line with time-of-day clock or not.

       By default, with no arguments, tickadj  reads the variables of  inter-
       est  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 oper-
       ations 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 



ntp 4.1.1b-r5							   tickadj(1)

UNIX/Linux commands referenced on this page:

1. which
2. time
3. clock
4. ntpd
5. as
6. at