Configuring the FSS

The same commands that you use with other scheduling classes in the Oracle Solaris system can be used with FSS. You can set the scheduler class, configure the scheduler's tunable parameters, and configure the properties of individual processes.

Note that you can use svcadm restart to restart the scheduler service. See svcadm(1M) for more information.

Listing the Scheduler Classes on the System

To display the scheduler classes on the system, use the dispadmin command with the -l option.

$ dispadmin -l
CONFIGURED CLASSES
==================

SYS     (System Class)
TS      (Time Sharing)
SDC     (System Duty-Cycle Class)
FSS     (Fair Share)
FX      (Fixed Priority)
IA      (Interactive) 

How to Make FSS the Default Scheduler Class

The FSS must be the default scheduler on your system to have CPU shares assignment take effect.

Using a combination of the priocntl and dispadmin commands ensures that the FSS becomes the default scheduler immediately and also after reboot.

1. Become root or assume an equivalent role.
2. Set the default scheduler for the system to be the FSS.

   # dispadmin -d FSS

   This change takes effect on the next reboot. After reboot, every process on the system runs in the FSS scheduling class.

3. Make this configuration take effect immediately, without rebooting.

   # priocntl -s -c FSS -i all

How to Manually Move Processes From the TS Class Into the FSS Class

You can manually move processes from one scheduling class to another scheduling class without changing the default scheduling class and rebooting. This procedure shows how to manually move processes from the TS scheduling class into the FSS scheduling class.

1. Become root or assume an equivalent role.
2. Move the init process (pid 1) into the FSS scheduling class.

   # priocntl -s -c FSS -i pid 1

3. Move all processes from the TS scheduling class into the FSS scheduling class.

   # priocntl -s -c FSS -i class TS

   ---

   Note - All processes again run in the TS scheduling class after reboot.

   ---

How to Manually Move Processes From All User Classes Into the FSS Class

You might be using a default class other than TS. For example, your system might be running a window environment that uses the IA class by default. You can manually move all processes into the FSS scheduling class without changing the default scheduling class and rebooting.

1. Become root or assume an equivalent role.
2. Move the init process (pid 1) into the FSS scheduling class.

   # priocntl -s -c FSS -i pid 1

3. Move all processes from their current scheduling classes into the FSS scheduling class.

   # priocntl -s -c FSS -i all

   ---

   Note - All processes again run in the default scheduling class after reboot.

   ---

How to Manually Move a Project's Processes Into the FSS Class

You can manually move a project's processes from their current scheduling class to the FSS scheduling class.

1. Become root or assume an equivalent role.
2. Move processes that run in project ID 10 to the FSS scheduling class.

   # priocntl -s -c FSS -i projid 10

   The project's processes again run in the default scheduling class after reboot.

How to Tune Scheduler Parameters

You can use the dispadmin command to display or change process scheduler parameters while the system is running. For example, you can use dispadmin to examine and tune the FSS scheduler's time quantum value. Time quantum is the amount of time that a thread is allowed to run before it must relinquish the processor.

To display the current time quantum for the FSS scheduler while the system is running, type:

$ dispadmin -c FSS -g
#
# Fair Share Scheduler Configuration
#
RES=1000
#
# Time Quantum
#
QUANTUM=110

When you use the -g option, you can also use the -r option to specify the resolution that is used for printing time quantum values. If no resolution is specified, time quantum values are displayed in milliseconds by default.

$ dispadmin -c FSS -g -r 100
#
# Fair Share Scheduler Configuration
#
RES=100
#
# Time Quantum
#
QUANTUM=11

To set scheduling parameters for the FSS scheduling class, use dispadmin -s. The values in file must be in the format output by the -g option. These values overwrite the current values in the kernel. Type the following:

$ dispadmin -c FSS -s file