kmtune(1M)

NAME

kmtune — query, set, or reset system parameters

SYNOPSIS

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

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

DESCRIPTION

kmtune is used to query, set, or reset system parameters. kmtune displays the value of all system parameters when used without any options or with the -S or -l option. kmtune reads the master files and the system description files of the kernel and kernel modules. Information on the running kernel is gathered with the tuneinfo() system call.

Changes to kernel parameters generally do not take effect until the kernel has been rebuilt and the system has been rebooted. Some kernel parameters can be changed in the running kernel. kmtune with the -u option will alter these parameters and avoid the need to rebuild and reboot.

Options

The following options are recognized by kmtune:

-l

Print a detailed report. The -l option cannot be used with the -r, -s, or -u options.

-d

Print a brief difference report. Only parameters where the planned and current values are different are listed. If the planned value is an 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.

-q name

Query the value of the specified system parameter.

-r name

Reset the value of a system parameter to the default.

-s name{=|+}value

Set the value to a 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

Specify the HP-UX system description file name. If not specified, /stand/system is used as the default.

-u

Update the currently running kernel. This modifies the -s and -r options, to update the running kernel as well as the system files. The values specified must be numeric. 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. When incrementing a value with the -s option the kernel and the system files are set to the value in the system file plus the increment value.

When used alone, or with -S, it updates all the dynamic parameters to match the numeric values stored in the system files. A warning is reported if any static parameters have differences. The order the parameters are listed in the system files is not important. The -d option can be used to look at the differences to get a preview of what a lone -u will do.

Use of -u requires super user privileges.

If the -q query option is specified, kmtune displays the following format:

Brief report without -l option

    Parameter        Current Dyn Planned          Module Version  
    ============================================================  
    name                                 value Y/- value                                          module version 

Detailed report with -l option

    Parameter:      name
    Current:        current value from running kernel
    Planned:        planned value from system file
    Default:        default value from master file
    Minimum:        minimum
    Module:         module
    Version:        version
    Dynamic:        Yes/No

If the -l option is specified without the -q query option, a detailed report on all the parameters is displayed. The information between the parameters is separated by blank lines.

If the parameter has no minimum value specified in a master file, minimum will be displayed as '-'. If the parameter is not supplied by kernel modules, module will be displayed as '-'. In the brief listing the module and version fields are blank unless the parameter comes from a dynamically loadable kernel module.

The Current field is an integer read from the running kernel. Some parameters are not stored in the running kernel and are displayed as '-'. The Value string is a copy of the default value or what is stored in a system file.

The Dynamic field, in the -l output, is either Yes or No, and indicates whether the parameter can be changed using -u. This avoids rebuilding and rebooting. In the brief listing Y is used to indicate dynamic parameters.

If the -s set option is specified with an equal (=) separator and the minimum value of the parameter is described in a master file, the value range is checked. If the minimum value or the specified value is a formula, the check is not made. More restrictive range checking may be done by the kernel whenever -u is used.

If the -s set option with a plus (+) separator is specified and the original value is non numeric, an error is reported.

NOTES

System administrators are encouraged to use kmsystem and kmtune instead of editing description files manually. File format of description files are subject to change, and kmtune is intended to provide compatibility in case of format change.

The -u option is new functionality that allows changes to values in the kernel that have always been constant before. Programs using pstat(), getrlimit(), or sysconf() may have been written with the previously correct assumption that the returned variables 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.

When lowering system limits, processes that exceed the new limit will be "grandfathered". Such processes may not be able to reallocate a resource that had just been released and may fail in ways that were very unlikely before. After lowering maxfiles, a process may be in violation of the new limit. If it closes a file and then reopens it, the open may fail. See settune(2).

RETURN VALUE

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

0: Successful.
1: Requested parameter is not found, the value is out of range, or the type of value is formula.
2: Syntax error.
3: Changes in static parameters were found when trying to dynamically update the running kernel.
>3: Environmental error.

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

EXAMPLES

# kmtune -q shmseg 
  Parameter        Current Dyn Planned    Module Version 
  ======================================================== 
  shmseg               120  Y  120 
# kmtune -s shmseg=155 
# kmtune -l -q shmseg 
  Parameter:      shmseg 
  Current:        120 
  Planned:        155 
  Default:        120  
  Minimum:        - 
  Module:         - 
  Version:        - 
  Dynamic:        Yes  
# kmtune -u shmseg  
  shmseg has been set to 155 (0x9b).  
# kmtune -r shmseg 
# kmtune -d 
  Parameter        Current Dyn Planned    Module Version 
  ======================================================== 
  shmseg               155  Y  120 

FILES

/usr/conf/master.d/*: Master configuration tables for kernel and kernel modules
/stand/system: Default HP-UX system description file
/stand/system.d/*: Kernel module system description files

kmtune(1M)

Technical documentation

» Table of Contents

» Index