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Commit 61cb5758 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
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cpuidle: Add cpuidle.governor= command line parameter 



Add cpuidle.governor= command line parameter to allow the default
cpuidle governor to be replaced.

That is useful, for example, if someone running a tickful kernel
wants to use the menu governor on it.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 800fb34a

Documentation/admin-guide/kernel-parameters.txt

+3 −0
Original line number Diff line number Diff line
@@ -674,6 +674,9 @@ 
	cpuidle.off=1	[CPU_IDLE]

			disable the cpuidle sub-system



	cpuidle.governor=

			[CPU_IDLE] Name of the cpuidle governor to use.



	cpufreq.off=1	[CPU_FREQ]

			disable the cpufreq sub-system

Documentation/admin-guide/pm/cpuidle.rst

+7 −0
Original line number Diff line number Diff line
@@ -566,6 +566,13 @@ processors implementing the architecture (i.e. CPU instruction set) in question, 
however, so it is rather crude and not very energy-efficient.  For this reason,

it is not recommended for production use.



The ``cpuidle.governor=`` kernel command line switch allows the ``CPUIdle``

governor to use to be specified.  It has to be appended with a string matching

the name of an available governor (e.g. ``cpuidle.governor=menu``) and that

governor will be used instead of the default one.  It is possible to force

the ``menu`` governor to be used on the systems that use the ``ladder`` governor

by default this way, for example.



The other kernel command line parameters controlling CPU idle time management

described below are only relevant for the *x86* architecture and some of

them affect Intel processors only.

drivers/cpuidle/cpuidle.c

+1 −0
Original line number Diff line number Diff line
@@ -702,4 +702,5 @@ static int __init cpuidle_init(void) 
}



module_param(off, int, 0444);

module_param_string(governor, param_governor, CPUIDLE_NAME_LEN, 0444);

core_initcall(cpuidle_init);

drivers/cpuidle/cpuidle.h

+1 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#define __DRIVER_CPUIDLE_H



/* For internal use only */

extern char param_governor[];

extern struct cpuidle_governor *cpuidle_curr_governor;

extern struct list_head cpuidle_governors;

extern struct list_head cpuidle_detected_devices;

drivers/cpuidle/governor.c

+7 −2
Original line number Diff line number Diff line
@@ -11,10 +11,13 @@ 
#include <linux/cpu.h>

#include <linux/cpuidle.h>

#include <linux/mutex.h>

#include <linux/module.h>

#include <linux/pm_qos.h>



#include "cpuidle.h"



char param_governor[CPUIDLE_NAME_LEN];



LIST_HEAD(cpuidle_governors);

struct cpuidle_governor *cpuidle_curr_governor;
@@ -86,9 +89,11 @@ int cpuidle_register_governor(struct cpuidle_governor *gov) 
	mutex_lock(&cpuidle_lock);

	if (__cpuidle_find_governor(gov->name) == NULL) {

		ret = 0;

		list_add_tail(&gov->governor_list, &cpuidle_governors);

		if (!cpuidle_curr_governor ||

		    cpuidle_curr_governor->rating < gov->rating)

		    !strncasecmp(param_governor, gov->name, CPUIDLE_NAME_LEN) ||

		    (cpuidle_curr_governor->rating < gov->rating &&

		     strncasecmp(param_governor, cpuidle_curr_governor->name,

				 CPUIDLE_NAME_LEN)))

			cpuidle_switch_governor(gov);

	}

	mutex_unlock(&cpuidle_lock);