Local Actions on Resource Control Values

Local actions are taken on a process that attempts to exceed the control value. For each threshold value that is placed on a resource control, you can associate one or more actions. There are three types of local actions: none, deny, and signal=. These three actions are used as follows:

Not all of the actions can be applied to every resource control. For example, a process cannot exceed the number of CPU shares assigned to the project of which it is a member. Therefore, a deny action is not allowed on the project.cpu-shares resource control.

Due to implementation restrictions, the global properties of each control can restrict the range of available actions that can be set on the threshold value. (See the rctladm(1M) man page.) A list of available signal actions is presented in the following table. For additional information about signals, see the signal(3HEAD) man page.

Table 6-3 Signals Available to Resource Control Values

Resource Control Flags and Properties

Each resource control on the system has a certain set of associated properties. This set of properties is defined as a set of flags, which are associated with all controlled instances of that resource. Global flags cannot be modified, but the flags can be retrieved by using either rctladm or the getrctl system call.

Local flags define the default behavior and configuration for a specific threshold value of that resource control on a specific process or process collective. The local flags for one threshold value do not affect the behavior of other defined threshold values for the same resource control. However, the global flags affect the behavior for every value associated with a particular control. Local flags can be modified, within the constraints supplied by their corresponding global flags, by the prctl command or the setrctl system call. See setrctl(2).

For the complete list of local flags, global flags, and their definitions, see rctlblk_set_value(3C).

To determine system behavior when a threshold value for a particular resource control is reached, use rctladm to display the global flags for the resource control . For example, to display the values for process.max-cpu-time, type the following:

$ rctladm process.max-cpu-time
	process.max-cpu-time  syslog=off  [ lowerable no-deny cpu-time inf seconds ]

The global flags indicate the following.

Use the prctl command to display local values and actions for the resource control.

$ prctl -n process.max-cpu-time $$
	process 353939: -ksh
	NAME    PRIVILEGE    VALUE    FLAG   ACTION              RECIPIENT
 process.max-cpu-time
         privileged   18.4Es    inf   signal=XCPU                 -
         system       18.4Es    inf   none 

The max (RCTL_LOCAL_MAXIMAL) flag is set for both threshold values, and the inf (RCTL_GLOBAL_INFINITE) flag is defined for this resource control. An inf value has an infinite quantity. The value is never enforced. Hence, as configured, both threshold quantities represent infinite values that are never exceeded.

Resource Control Enforcement

More than one resource control can exist on a resource. A resource control can exist at each containment level in the process model. If resource controls are active on the same resource at different container levels, the smallest container's control is enforced first. Thus, action is taken on process.max-cpu-time before task.max-cpu-time if both controls are encountered simultaneously.

Figure 6-1 Process Collectives, Container Relationships, and Their Resource Control Sets

Global Monitoring of Resource Control Events

Often, the resource consumption of processes is unknown. To get more information, try using the global resource control actions that are available with the rctladm command. Use rctladm to establish a syslog action on a resource control. Then, if any entity managed by that resource control encounters a threshold value, a system message is logged at the configured logging level. See Chapter 7, Administering Resource Controls (Tasks) and the rctladm(1M) man page for more information.

Applying Resource Controls

Each resource control listed in Table 6-1 can be assigned to a project at login or when newtask, su, or the other project-aware launchers at, batch, or cron are invoked. Each command that is initiated is launched in a separate task with the invoking user's default project. See the man pages login(1), newtask(1), at(1), cron(1M), and su(1M) for more information.

Updates to entries in the project database, whether to the /etc/project file or to a representation of the database in a network name service, are not applied to currently active projects. The updates are applied when a new task joins the project through login or newtask.

Temporarily Updating Resource Control Values on a Running System

Values changed in the project database only become effective for new tasks that are started in a project. However, you can use the rctladm and prctl commands to update resource controls on a running system.

Updating Logging Status

The rctladm command affects the global logging state of each resource control on a system-wide basis. This command can be used to view the global state and to set up the level of syslog logging when controls are exceeded.

Updating Resource Controls

You can view and temporarily alter resource control values and actions on a per-process, per-task, or per-project basis by using the prctl command. A project, task, or process ID is given as input, and the command operates on the resource control at the level where the control is defined.

Any modifications to values and actions take effect immediately. However, these modifications apply to the current process, task, or project only. The changes are not recorded in the project database. If the system is restarted, the modifications are lost. Permanent changes to resource controls must be made in the project database.

All resource control settings that can be modified in the project database can also be modified with the prctl command. Both basic and privileged values can be added or be deleted. Their actions can also be modified. By default, the basic type is assumed for all set operations, but processes and users with superuser privileges can also modify privileged resource controls. System resource controls cannot be altered.

Commands Used With Resource Controls

The commands that are used with resource controls are shown in the following table.

The resource_controls(5) man page describes resource controls available through the project database, including units and scaling factors.