Autotune(4)                                              Autotune(4)


       NAME
             Autotune - autotuning tunable parameter definitions

       SYNOPSIS
             Autotune

       DESCRIPTION
             One of the Installable Driver/Tunable Parameters kernel
             configuration files, an 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,
             if the memory size has changed.  The autotuning can be
             overridden by using idtune.  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 min-max-or-default 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 constructed.

             min-max-or-default
                       A string used to specify whether this line  pertains
                       to  the default value (DEF), minimum value (MIN), or
                       maximum  value  (MAX)  in  the   mtune   file   line
                       constructed.




                           Copyright 1994 Novell, Inc.               Page 1

      Autotune(4)                                              Autotune(4)


            linear-or-step
                      The string LINEAR or STEP, used to determine how  to
                      calculate  the  value  for  memory  sizes in between
                      those   specified.    Linear   will    use    linear
                      interpolation  between  the  two  closest points, or
                      linear extrapolation from the last two points if the
                      largest  memory  size  specified is smaller than the
                      amount of  memory  in  the  system  and  has  LINEAR
                      specified.   STEP  will  use the value from the next
                      smaller memory size.

            memsize   The memory size, in megabytes, for which  this  line
                      specifies the tunable's minimum, maximum, or default
                      value.

            value     The value to be assigned to the  tunable's  minimum,
                      maximum, or default value at the given memory size.

            For detailed information on Autotune parameters, refer to  the
            tunable  parameters  chapter  in  your  system  administration
            documentation.

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























                          Copyright 1994 Novell, Inc.               Page 2