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cpuidle: Add cpuidle.governor= command line parameter

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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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2018-12-05 23:45:34 +01:00
parent 800fb34a99
commit 61cb5758d3
5 changed files with 19 additions and 2 deletions
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3
Documentation/admin-guide/kernel-parameters.txt
View File

@ -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

7
Documentation/admin-guide/pm/cpuidle.rst
View File

@ -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.

1
drivers/cpuidle/cpuidle.c
View File

@ -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);

1
drivers/cpuidle/cpuidle.h
View File

@ -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;

9
drivers/cpuidle/governor.c
View File

@ -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);