Installation guide

The following reference pages contain detailed information on using the
Class Scheduler commands and options:
• class_scheduling
(4)
• class_admin(8)
• runclass(1)
• classcntl(2)
Enter the following command to obtain on-line help for class_admin:
# /usr/sbin/class_admin help
4.7.1 Class Scheduler Overview
To use the class scheduler, you must first create a database file and
populate the file with one or more classes. Each class is assigned a CPU
value that controls its access to processing time, expressed as a percentage
of the total CPU time availability. One or more applications or groups of
applications can be assigned to a class, identified according to a unique
system process identifier such as:
• UID - user identifier, a unique number assigned to each user account
(login).
• GID - group identifier, a number or name assigned to several user
accounts to indicate that they belong to the same group.
• PID - process identifier.
• PGID - process group identifier
• SESS - session identifier
Note that process identifiers that are temporary, such as a PID, do not
persist across a reboot and cease to exist when a task is completed. They
are not stored in the database and have no effect when the system or task
is restarted.
Once the database is established, you can enable class scheduling to start a
class scheduling daemon and put the CPU access restrictions into effect.
Other commands enable you to review classes, change contents or
scheduling parameters, and delete components or entire classes. When a
class scheduling database is configured and enabled, you can:
• Execute a task (process) according to the CPU access value set for a
specific class using runclass . For example, you might set a value for
interactive operations that is much higher than background processes
such as print daemons. To temporarily use the higher value for a print
job, you can execute the lpr command in the same class as interactive
operations.
4–28 Customizing the System Environment