Changing scheduler configuration

Changing scheduler configuration requires changing one or more of the tunable parameters or the configuration tables fp_dptbl, ts_dptbl, fc_dptbl, and ts_kmdpris. This is the only way to change the size of the configuration tables. Changes made in this way are permanent; that is, the changes apply until another change if made. See ``Changing scheduler parameters with dispadmin'' for a way to make a temporary change on a running system.

Use the following procedure to change the scheduler configuration:

1. Identify the appropriate tunable file in the /etc/conf/mtune.d directory or the appropriate configuration table in the /etc/conf/pack.d directory.

2. Change the tunable parameter(s).

3. Rebuild the kernel.

Removing a scheduler class

For systems that do not need fixed priority processes, it may make sense to remove the fixed priority class, thereby making it impossible to create fixed priority processes. By not having fixed priority processes, you avoid their non-pageable u-blocks and you avoid the possibility of a runaway process monopolizing the machine.

Use the following procedure to remove the fixed priority scheduler class:

1. Open the file for editing.

2. In the file /etc/conf/sdevice.d/fp, change the line

      fp Y 1 0 . . . .
   

   so that there is an ``N'' in the second column:

      fp N 1 0 . . . .
   

3. Rebuild the kernel.

Installing a Time-Sharing scheduler class

By default, the time-sharing scheduler class is installed. Therefore, you need to install this class only if you first remove it.

Use the following procedure to install the time-sharing class:

1. Ensure that the Driver.o module is in the /etc/conf/pack.d/ts directory.

2. In the /etc/conf/sdevice.d/ts file, edit the line

      ts N . . .
   

   to

      ts Y . . .
   

   (The module is automatically configured unless it is explicitly excluded, that is, by having N in the second column.)

3. Verify the value of INITCLASS using /etc/conf/bin/idtune -g; make sure that your configuration is assigning the appropriate default scheduler class.

4. Build the kernel.

Installing a fixed class scheduler class

By default, the fixed class scheduler class is installed. Therefore, you need to install this class only if you first remove it.

Use the following procedure to install the fixed class:

1. Ensure that the Driver.o module is in the /etc/conf/pack.d/fc directory.

2. In the /etc/conf/sdevice.d/fc file, edit the line

      fc N . . .
   

   to

      fc Y . . .
   

   (The module is automatically configured unless it is explicitly excluded, that is, by having N in the second column.)

3. Verify the value of INITCLASS using /etc/conf/bin/idtune -g; make sure that your configuration is assigning the appropriate default scheduler class.

4. Build the kernel.

Installing a fixed priority scheduler class

By default, the fixed priority scheduler class is installed. Therefore, you need to install this class only if you first remove it.

Use the following procedure to install the fixed priority class:

1. Make sure that the Driver.o module is in the /etc/conf/pack.d/fp directory.

2. In the /etc/conf/sdevice.d/fp file, edit the line

      fp N  . . .
   

   to

      fp Y  . . .
   

   (The module is not configured unless it is explicitly included.)

3. Verify the value of INITCLASS using /etc/conf/bin/idtune -g; make sure that your configuration is assigning the appropriate default scheduler class.

4. Build the kernel.