tickadj(8)                                                                                                            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 timekeeping-related variables in older kernels that do not
       have support for precision ttimekeeping, including HP-UX, SunOS, Ultrix, SGI and probably 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 kernels 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 Pro-
       tocol (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 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.

SEE ALSO
       ntpd(8)

       HTML documentation in ntp-doc package.

       This file was automatically generated from HTML source.




                                                                                                                      tickadj(8)