Agent CPU Resource Control

You can control the priority of the Tenable 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 Tenable Nessus Agent depends 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 Tenable Nessus Agent CLI 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 following table.

Preference Value

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

Note: Setting your process_priority preference value to low could cause longer running scans. You may need to increase your scan-window timeframe 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 Tenable Nessus Agent CLI Commands .

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

Tip:If you have many agents (10,000+), you 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. Does 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. Does not use more than eight cores.

 high low, medium, or high