mtune(4) mtune(4)
mtune - default system tunable parameters
The directory /var/sysgen/mtune contains information about all the system
tunable parameters, including default values. The files in this
directory should never be changed. Instead, use the systune(1M) utility
to change parameters in the /var/sysgen/stune file.
Each loadable module can have its own mtune file, which is placed in the
mtune directory and has the same name as the module. Parameters in an
mtune file may be grouped together in groups, according to the nature of
the parameters. For example, all parameters dealing with the number of
processes that can run on the system at any given time are grouped
together in the numproc group in the kernel module. The syntax of an
mtune module file is given below:
[group_name: [flag]]
parameter_clauses
Names that end with a colon character, :, are group names. Parameters
can be grouped together in groups so that one sanity checking function
can be used to verify the values and the dependencies between these
variables. The group name is optional if there is only one group in the
module. For this case, the configuration tools use the module name as
the group name.
The group name is followed by a flag. The flag can be either run or
static. If the flag is run, this group of tunable variables can be
changed with the command systune on a running system. Otherwise, the
variables are set at initialization time and can be changed only by
creating a new kernel and booting that kernel. Modules with no group
specifier or a group specifier without a flag default to static.
Each tunable parameter is specified by a single line, a parameter clause,
in the file. Blank lines and lines beginning with # or * are considered
comments and are ignored. The syntax for each line is:
name[,tag] default_value [[min_value [max_value [ll|LL]]
name The name of the tunable parameter. It is used to pass
the value to the system when a kernel is built or
changed by systune command. Since this name is made
into a global variable name, using a long descriptive
name is useful to avoid any name collisions.
tag This optional field is separated from name by a comma.
It is used to qualify whether the tunable parameter
should be used in the configuration being built. This
allows a single tune file to be used in multiple
different configurations. Parameters without any tag
are always used, those with a tag are only used if the
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mtune(4) mtune(4)
tag matches one of the tags specified in the system file
(see system(4)). Only one tag is permitted on a given
line.
default_value The default value of the tunable parameter. If the
value is not specified in the stune file, this value is
used when the system is built. This value is mandatory.
min_value The minimum allowable value for the tunable parameter.
If the parameter is set in the stune file, the lboot
command checks that the new value is equal to or greater
than this value. The command systune also verifies the
new value against this value before changing the system.
This field is optional; a value of 0 is equivalent to
not specifying a value.
max_value The maximum allowable value for the tunable parameter.
If the parameter is set in the stune file, the lboot
command checks that the new value is equal to or less
than this value. The command systune also verifies the
new value against this value before changing the system.
This field is optional; a value of 0 is equivalent to
not specifying a value.
ll|LL By default, each tunable parameter is represented by an
global variable in the kernel of type int (32 bits).
Some tunable parameters may need to be specified as 64
bit quantities. Adding an ll or LL to the end of the
parameter specification causes lboot to represent the
parameter as a long long.
/var/sysgen/mtune/* default system tunable parameters
/var/sysgen/stune local settings for system tunable parameters
/var/sysgen/system/* master system configuration files
lboot(1M), systune(1M), stune(4), system(4).
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