Agent CPU Resource Control

You can control the priority of the Nessus Agent relative to the priority of other tasks running on the system by using the process_priority preference. Due to the relative nature of this preference, the amount of system resources consumed by the Nessus Agent will depend not only on the value of the process_priority preference, but also on the overall load on the system. This may reflect on system monitors as if the agent is consuming resources over the higher priority processes. For resource control commands see Nessus CLI Agent Commands.

Note: There may be a slight delay between setting a value for process_priority and seeing the change reflected in Linux, Mac OS nice values or Windows Priority Class.

To see the effect of the process_priority preference, see the table below.

Preference Value

Windows - Priority Class Mac OS - Nice Value Linux - Nice Value
normal (default) normal 0 0
low below normal 10 10
high above normal -10 -5

Note: Setting your process_priority preference value to low could cause longer running scans. You may need to increase your scan-window time frame to account for this value.

Agent CPU Resource Control Advanced Settings

You can configure the following agent settings in the command line interface using the nessuscli utility.

Use the command # nessuscli fix --set setting=value. For more information, see Nessus CLI Agent Commands.

For more information, and a complete list of CLI-configurable settings, see Advanced Settings.

Tip: Customers with a large number of agents (10,000+) may want to configure the agent_merge_audit_trail, agent_merge_kb, agent_merge_journal_mode, and agent_merge_synchronous_setting settings. Modifying these settings can dramatically lower the amount of time it takes to merge agent scan results. Review the descriptions in the following table for suggested configurations.

Name

Setting

Description

Default Valid Values
Plugin Compilation Performance plugin_load_performance_mode

Sets plugin compilation performance, which affects CPU usage. Low performance slows down plugin compilation, but reduces the agent's CPU consumption. Setting the performance to medium or high means that plugin compilation completes more quickly, but the agent consumes more CPU. Target ranges for each setting value are:

  • low: Less than 50% of a single core used by nessusd during plugin compilation.
  • medium: 100% of two cores used by nessusd during plugin compilation.
  • high: Unchanged from previous versions. Will not use more than eight cores.

high

low, medium, or high

Scan Performance scan_performance_mode

Sets scan performance, which affects CPU usage. Low performance slows down scans, but reduces the agent's CPU consumption. Setting the performance to medium or high means that scans complete more quickly, but the agent consumes more CPU. Target ranges for each setting value are:

  • low: Less than 50% of a single core used by nessusd during a scan.
  • medium: 100% of two cores used by nessusd during a scan.
  • high: Unchanged from previous versions. Will not use more than eight cores.

high low, medium, or high