CPU load monitor

Module for monitoring CPU load. More...

Macros
#define	CPU_LOAD_PERMILLE_TO_PERCENT(permille)
	Convert a per mille CPU load value to whole percent.

Typedefs
typedef void(*	cpu_load_cb_t) (uint8_t percent)

Functions
int	cpu_load_get_cpu (unsigned int cpu_id, bool reset)
	Get CPU load for a specific CPU.
int	cpu_load_get (bool reset)
	Get CPU load for the current CPU.
void	cpu_load_on_enter_idle (void)
	Hook called on entering CPU idle.
void	cpu_load_on_exit_idle (void)
	Hook called on exiting CPU idle.
void	cpu_load_log_control (bool enable)
	Control periodic CPU load report.
int	cpu_load_cb_reg (cpu_load_cb_t cb, uint8_t threshold_percent)
	Optional registration of callback when load is greater or equal to the threshold.
static int	cpu_load_metric_get (int cpu_id)
	Get CPU load as a percentage for a specific CPU.

Detailed Description

Module for monitoring CPU load.

The CPU load is the fraction of time the CPU spends outside of the idle state. Two measurement backends are available and selected through Kconfig:

• CONFIG_CPU_LOAD_BACKEND_RUNTIME_STATS 

  derives the load from the scheduler per-CPU runtime statistics. It is portable across architectures and supports multiple CPUs.

• CONFIG_CPU_LOAD_BACKEND_IDLE_HOOK 

  measures the load using the architecture idle hooks. It has lower overhead and can optionally use a hardware counter for higher precision (the counter path is single-CPU only). Available on any architecture that emits the idle hooks (

  CONFIG_ARCH_HAS_CPU_IDLE_HOOKS 

  ).

Regardless of the backend, the load is reported in per mille (0...1000).

Macro Definition Documentation

CPU_LOAD_PERMILLE_TO_PERCENT

#define CPU_LOAD_PERMILLE_TO_PERCENT

(

permille

)

#include <cpu_load.h>

Value:

((permille) / 10)

Convert a per mille CPU load value to whole percent.

Typedef Documentation

cpu_load_cb_t

typedef void(* cpu_load_cb_t) (uint8_t percent)

#include <cpu_load.h>

Function Documentation

cpu_load_cb_reg()

int cpu_load_cb_reg	(	cpu_load_cb_t	cb,
		uint8_t	threshold_percent )

#include <cpu_load.h>

Optional registration of callback when load is greater or equal to the threshold.

Parameters

cb	Pointer to the callback function. NULL will cancel the callback.
threshold_percent	Threshold [0...100]. CPU load equal or greater that this will trigger the callback.

Return values

0	- Callback registered/cancelled.
-EINVAL	if the threshold is invalid.

cpu_load_get()

int cpu_load_get

(

bool

reset

)

#include <cpu_load.h>

Get CPU load for the current CPU.

Parameters

reset

Reset the measurement window after reading.

Return values

>=0	CPU load in per mille (0...1000).
<0	Negative errno code on failure.

cpu_load_get_cpu()

int cpu_load_get_cpu	(	unsigned int	cpu_id,
		bool	reset )

#include <cpu_load.h>

Get CPU load for a specific CPU.

Parameters

cpu_id	CPU index for which to get the load.
reset	Reset the measurement window after reading.

Return values

>=0	CPU load in per mille (0...1000).
<0	Negative errno code on failure.

cpu_load_log_control()

void cpu_load_log_control

(

bool

enable

)

#include <cpu_load.h>

Control periodic CPU load report.

Report logging is by default enabled.

Parameters

enable

true to enable report logging and false to disable.

cpu_load_metric_get()

int cpu_load_metric_get ( int cpu_id )

inlinestatic

#include <cpu_load.h>

Get CPU load as a percentage for a specific CPU.

Deprecated

Use cpu_load_get_cpu() instead. Note that cpu_load_get_cpu() returns the load in per mille rather than percent.

Parameters

cpu_id

CPU index for which to get the load.

Return values

>=0	CPU load in percent (0...100).
<0	Negative errno code on failure.

cpu_load_on_enter_idle()

void cpu_load_on_enter_idle

(

void

)

#include <cpu_load.h>

Hook called on entering CPU idle.

Only used by the idle-hook backend; called from the architecture idle path.

cpu_load_on_exit_idle()

void cpu_load_on_exit_idle

(

void

)

#include <cpu_load.h>

Hook called on exiting CPU idle.

Only used by the idle-hook backend; called from the architecture idle path.