kmtune(1M)

NAME

kmtune — query, set, or reset system parameters

SYNOPSIS

/usr/sbin/kmtune [-d] [-l] [[-q name]...] [-S system_file]

/usr/sbin/kmtune [-u] [[-s name {=|+}value]...] [[-r name]...] [-c comment] [-S system_file]

/usr/sbin/kmtune [[-e value]...]

DESCRIPTION

kmtune is an obsolete command that is replaced by kctune(1M). Users are encouraged to migrate to kctune(1M). kmtune will be removed in a future release of HP-UX. The behavior of some of kmtune's options have changed and they are noted in the appropriate sections below.

kmtune is used to query, set, or reset system parameters. kmtune displays the planned values of all system parameters when used without any options or with the -l option. kmtune gathers information on the running kernel using the tuneinfo2() system call.

By default, kmtune's changes affect the currently running kernel configuration, marked to take effect at next boot. If the -u option is specified, kmtune's changes affect the current configuration, and take effect immediately. See kconfig(5) for more information on kernel configurations.

Options

The following options are recognized by kmtune:

-c text: Specify an optional comment string. All changes to the kernel parameters are logged with the date, old value, new value, user id and this comment. This option is used with -r and -s. The comment text will generally need to be quoted so that it is interpreted as a single parameter by the shell. The comment text may contain newlines. The log is written to the file /var/adm/kc.log. See kconfig(5) and kclog(1M) for more information about the kernel configuration log file.
-d: Print a brief difference report. Only parameters where the planned and current values are different are listed. If the planned value is a formula, it is NOT considered different from the current value. This option is useful to insure that only desired changes will be made on a subsequent invocation of kmtune -u. The -d option cannot be used with the -r, -s, or -u options.
-e value: Evaluate the expression given by "value". The expression is anything allowed in the -s option. The output will always be in decimal.
-l: Print a detailed report. The -l option cannot be used with the -r, -s or -u options.
-q name: Query the value of the specified system parameter.
-r name: Reset the value of the specified system parameter to the default.
-s name{=|+}value: Set the value of the specified system parameter. If the separator is an equal sign (=), the parameter is set to the value specified. If the separator is a plus sign (+), the parameter is incremented by the value specified. Negative values cannot be used with plus sign (+). The name{=|+}value format must not include spaces or tabs.
-S system_file: This option is obsolete. It is accepted for compatibility purposes but has no effect.
-u: Update the current kernel configuration. This modifies the -s and -r options so that their effects take effect immediately rather than at next boot. The whole command will fail if any non dynamic parameters are being set. The -s and -r options are processed in the order they are listed. At least one -s or -r option must be specified.

The expressions used with the -s and -e options are built of literal values, the upper case names of other kernel parameters, and the following operators: ( and ), the unary operators ~, !, -, and +, the binary operators *, /, %, +, -, <<, >>, <, <=, >, >=, &, ~, |, ==, !=, &&, and ||, and the ternary operator ?:.

Using -s to create a circular dependency in the values of the kernel parameters is not allowed.

Notes

Changing kernel parameters dynamically is a fairly new feature. Programs using pstat(2), getrlimit(2), or sysconf(2) may have been written with the previously correct assumption that the returned values do not vary while the system is running. The use of kmtune to modify the running kernel may cause such programs to produce erroneous results or even abort.

Some dynamic kernel parameters can be raised dynamically, but cannot be lowered without rebuilding the kernel and rebooting. See the manual pages for those parameters for details.

When dynamically lowering per-process limits, processes that exceed the new limit will be "grandfathered". Such processes will retain the old limit. The old limit will also apply to any child processes they create after the change. Some parameters have exceptions to this general policy; see the manual pages for those parameters for details.

It is possible to put multiple -s and -r options on a single kmtune command. kmtune will try to make all of the changes, in the order listed. If an error occurs with one of the changes, the state of the other changes is not defined.

RETURN VALUE

Upon completion, kmtune returns with one of the following exit values:

0: Successful.
1: Changes have been made and will take effect at next boot.
2: An error occurred.

Results of query requests are sent to stdout. Error and warning messages are sent to stderr.

FILES

/var/adm/kc.log: Log of all kernel configuration changes

kmtune(1M)

Technical documentation

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