Technical data

Managing User Accounts
7.8 Restricting the Use of Accounts
Note that network connections are treated differently than interactive connections
and batch jobs. See the documentation for the network software you are running
for information about disconnecting established network connections.
7.8.3 Restricting CPU Time
OpenVMS Version 7.3 and later enables you to perform class scheduling using the
SYSMAN interface.
You can limit the amount of CPU time that a user receives on the system by
placing the user into a scheduling class. Each scheduling class is assigned a
percentage of the overall CPU time on the system. As the system runs, the set of
users in each scheduling class is limited to the percentage of CPU execution time
allocated to that class. Users in a scheduling class can get additional CPU time
if windfall is enabled for their scheduling class. Enabling windfall allows the
system to give a small amount of CPU time to a scheduling class when a CPU is
idle and the time alloted to that scheduling class has already been depleted.
To invoke the class scheduler, use the SYSMAN interface. SYSMAN allows you to
create, delete, modify, suspend, resume, and display scheduling classes. Table 7–7
describes the SYSMAN command, class_schedule, and its sub-commands.
Table 7–7 SYSMAN command: class_schedule
Sub-command Function
Add Creates a new scheduling class
Delete Deletes a scheduling class
Modify Modifies the characteristics of a scheduling class
Show Shows the characteristics of a scheduling class
Suspend Suspends temporarily a scheduling class
Resume Resumes a scheduling class
By using a permanent class scheduler, a process is placed into a scheduling class,
if appropriate, at process creation time. When a new process is created, it needs
to be determined whether this process belongs to a scheduling class. Since to
determine this relies upon data in the SYSUAF file, and the Loginout image
already has the process’ information from this file, Loginout class schedules the
process if it determines that the process belongs to a scheduling class.
When you use the SYSMAN command CLASS_SCHEDULE ADD, you can do the
following:
• Create a scheduling class
• Identify users in the class, by account name, user name, or UIC
• Specify the percent of CPU time alloted to processes run by users in this
scheduling class on primary days and secondary days and specify hourly
ranges on during which the CPU time restriction applies
• Specify days as either primary days or secondary days, and specify different
CPU time restrictions for primary days and secondary days
• Allow a scheduling class to receive additional CPU time when the CPU is idle
Managing User Accounts 7–29