Autotune(4dsp)

Autotune -- autotuning tunable parameter definitions

Synopsis

   Autotune

Description

One of the Installable Driver/Tunable Parameters kernel configuration files, the Autotune file contains definitions for the default, minimum, and maximum values for tunables that should change with the amount of memory present. Lines in the /etc/conf/cf.d/mtune file are created for these variables based on this information. The information is also passed to the kernel as a structure in the /etc/conf/pack.d/module-name/tune.c file. This is used to retune the tunable at boot time, if the memory size has changed. The autotuning can be overridden by using idtune(1M). Autotune files exist on a per-module basis, for those modules that have autotuned parameters. idinstall(1M) stores the module's Autotune file information in /etc/conf/autotune.d/module-name, where the file module-name is the name of the module being installed. Package scripts should never access /etc/conf/autotune.d files directly; only the idinstall and idtune commands should be used.

Each tunable is specified on multiple lines of the form:

   parameter-name record-type linear-or-step memsize value

All fields are positional and must be separated by white space. Blank lines and lines beginning with ``#'' or ``*'' are considered comments and ignored.

The Autotune file fields are:

parameter-name: A string (maximum of 20 characters) used as the parameter name in the mtune file line that is constructed.
record-type: A PHYS entry in this field indicates that the parameter is autotuned using a method based on the amount of general purpose memory available. If the ``record type'' is ``PHYS'' subsequent fields are not used. Otherwise, the parameter is autotuned using a (default) method that takes both general purpose and kernel virtual memory into account. In this case, information is provided about whether the line pertains to the default value (``DEF''), minimum value (``MIN''), or maximum value (``MAX'') in the mtune file line that is constructed.
linear-or-step: The string ``LINEAR'' or ``STEP'' is used to indicate how to calculate the value for memory sizes in between those specified. Linear uses linear interpolation between the two closest points, or linear extrapolation from the last two points if the system has more memory than the largest tune point specified, and if the largest tune point is specified as ``LINEAR''. ``STEP'' will use the value from the next smaller memory size. If the ``record type'' is ``PHYS'' this field is not used.
memsize: The memory size, in megabytes, for which this line specifies the tunable's minimum, maximum, or default value. If the ``record type'' is ``PHYS'' this field is not used.
value: The value to be assigned to the tunable's minimum, maximum, or default value at the given memory size. If the ``record type'' is ``PHYS'' this field is not used.

References

idbuild(1M), idinstall(1M), idtune(1M), Mtune(4dsp), Space.c(4dsp), stune(4dsp)