CPU measurement module

Use the CPU measurement module to monitor CPU load.

Module events

Source Module	Input Event	This Module	Output Event	Sink Module
Source modules for module_state_event	module_state_event	cpu_meas
			cpu_load_event	None
			module_state_event	Sink modules for module_state_event

Note

See the Application overview for more information about the event-based communication in the nRF Desktop application and about how to read this table.

Configuration

To enable this module, use the CONFIG_DESKTOP_CPU_MEAS_ENABLE Kconfig option. This option selects the CONFIG_NRF_CPU_LOAD Kconfig option, which enables the CPU load measurement library that is used to perform the measurements.

Set the time between subsequent CPU load measurements, in milliseconds, using the CONFIG_DESKTOP_CPU_MEAS_PERIOD option.

Measurement results

The module can provide the measurement results in the following ways:

• CONFIG_DESKTOP_CPU_MEAS_RESULT_NRF_PROFILER - The module uses the nRF Profiler API directly to emit the CPU load. This minimizes the impact of providing the results on the measured CPU load. The option depends on the CONFIG_NRF_PROFILER Kconfig option and is enabled by default if the nRF Profiler is enabled.

• CONFIG_DESKTOP_CPU_MEAS_RESULT_EVENT - The module submits the CPU load as a cpu_load_event. The option selects the CONFIG_DESKTOP_CPU_LOAD_EVENT Kconfig option, which enables the event. The option is enabled by default unless the CONFIG_DESKTOP_CPU_MEAS_RESULT_NRF_PROFILER option is enabled.

You must enable at least one of these options. You can enable both options at the same time.

Implementation details

The module periodically reads the CPU load, provides the result, and resets the measurement. If reading the CPU load fails, the module reports an error state and stops the measurements.

The CPU load is presented in 0.001% units. Depending on the configuration, the result is provided in the following ways:

• Through the nRF Profiler event - The module registers the cpu_load nRF Profiler event type with a single load field. The event is emitted only if profiling of the event is enabled.

• Through the application event - The cpu_load_event.load presents the CPU load. The event can be displayed in the logs or using the nRF Profiler.