Managing Systems and Workgroups: A Guide for HP-UX System Administrators
Configuring a System
Reconfiguring the Kernel (HP-UX 11i Version 2)
Chapter 3 339
To set a tunable to Default, either of these assignments will work.
(Setting a user-defined tunable to Default causes it to be removed.)
# kctune nproc=
# kctune nproc=default
Assignments can be to expressions, as noted above. Note that the
assignment may need to be quoted to avoid interpretation by the shell.
# kctune 'nkthread=nproc*2+100'
To create a user-defined tunable, use the -u (user-defined) option when
you assign the tunable a value. The -u option is not needed to change the
value of an existing user-defined tunable.
Using the += symbol, you can increase the value of a tunable (by 100, in
this example):
# kctune nproc+=100
Using the >= symbol, you can ensure a minimum value of a tunable. The
command:
# kctune 'nproc>=5000'
will set nproc to 5000 if its current value is below 5000. If its current
value is already 5000 or greater, it will be left unchanged. Note that the
assignment was quoted to avoid interpretation by the shell.
See the kctune (1M) manpage for details.
When you change a tunable value using a command like the above
examples, the change will be made immediately to the currently running
system, if possible. Sometimes it’s not possible to make the change
immediately; for example, you might be trying to reduce the maximum
value of some resource to below the current usage. Also, there are some
tunables that cannot be changed without a reboot. In those cases, kctune
will hold the change and apply it at next boot. If any change on the
kctune command line has to be held for next boot, they all will be.
Sometimes you may want to force a change to be held for next boot,
instead of applying it immediately. In these cases you can use the -h
(hold) option to kctune to force that behavior. HP recommends that this
option be used only when the next boot is expected to be soon. If, for
example, the next boot doesn’t happen for months after making such a
change, the system administrator could be unpleasantly surprised at the
effect of a pending change that had been forgotten.