Commit cb5d8c45 authored by Joao Martins's avatar Joao Martins Committed by Rafael J. Wysocki
Browse files

cpuidle: allow governor switch on cpuidle_register_driver() 



The recently introduced haltpoll driver is largely only useful with
haltpoll governor. To allow drivers to associate with a particular idle
behaviour, add a @governor property to 'struct cpuidle_driver' and thus
allow a cpuidle driver to switch to a *preferred* governor on idle driver
registration. We save the previous governor, and when an idle driver is
unregistered we switch back to that.

The @governor can be overridden by cpuidle.governor= boot param or
alternatively be ignored if the governor doesn't exist.

Signed-off-by: default avatarJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent cd4c0763

drivers/cpuidle/cpuidle.h

+2 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
/* For internal use only */

extern char param_governor[];

extern struct cpuidle_governor *cpuidle_curr_governor;

extern struct cpuidle_governor *cpuidle_prev_governor;

extern struct list_head cpuidle_governors;

extern struct list_head cpuidle_detected_devices;

extern struct mutex cpuidle_lock;
@@ -22,6 +23,7 @@ extern void cpuidle_install_idle_handler(void); 
extern void cpuidle_uninstall_idle_handler(void);



/* governors */

extern struct cpuidle_governor *cpuidle_find_governor(const char *str);

extern int cpuidle_switch_governor(struct cpuidle_governor *gov);



/* sysfs */

drivers/cpuidle/driver.c

+25 −0
Original line number Diff line number Diff line
@@ -254,12 +254,25 @@ static void __cpuidle_unregister_driver(struct cpuidle_driver *drv) 
 */

int cpuidle_register_driver(struct cpuidle_driver *drv)

{

	struct cpuidle_governor *gov;

	int ret;



	spin_lock(&cpuidle_driver_lock);

	ret = __cpuidle_register_driver(drv);

	spin_unlock(&cpuidle_driver_lock);



	if (!ret && !strlen(param_governor) && drv->governor &&

	    (cpuidle_get_driver() == drv)) {

		mutex_lock(&cpuidle_lock);

		gov = cpuidle_find_governor(drv->governor);

		if (gov) {

			cpuidle_prev_governor = cpuidle_curr_governor;

			if (cpuidle_switch_governor(gov) < 0)

				cpuidle_prev_governor = NULL;

		}

		mutex_unlock(&cpuidle_lock);

	}



	return ret;

}

EXPORT_SYMBOL_GPL(cpuidle_register_driver);
@@ -274,9 +287,21 @@ EXPORT_SYMBOL_GPL(cpuidle_register_driver); 
 */

void cpuidle_unregister_driver(struct cpuidle_driver *drv)

{

	bool enabled = (cpuidle_get_driver() == drv);



	spin_lock(&cpuidle_driver_lock);

	__cpuidle_unregister_driver(drv);

	spin_unlock(&cpuidle_driver_lock);



	if (!enabled)

		return;



	mutex_lock(&cpuidle_lock);

	if (cpuidle_prev_governor) {

		if (!cpuidle_switch_governor(cpuidle_prev_governor))

			cpuidle_prev_governor = NULL;

	}

	mutex_unlock(&cpuidle_lock);

}

EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);

drivers/cpuidle/governor.c

+4 −3
Original line number Diff line number Diff line
@@ -20,14 +20,15 @@ char param_governor[CPUIDLE_NAME_LEN]; 


LIST_HEAD(cpuidle_governors);

struct cpuidle_governor *cpuidle_curr_governor;

struct cpuidle_governor *cpuidle_prev_governor;



/**

 * __cpuidle_find_governor - finds a governor of the specified name

 * cpuidle_find_governor - finds a governor of the specified name

 * @str: the name

 *

 * Must be called with cpuidle_lock acquired.

 */

static struct cpuidle_governor * __cpuidle_find_governor(const char *str)

struct cpuidle_governor *cpuidle_find_governor(const char *str)

{

	struct cpuidle_governor *gov;
@@ -87,7 +88,7 @@ int cpuidle_register_governor(struct cpuidle_governor *gov) 
		return -ENODEV;



	mutex_lock(&cpuidle_lock);

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

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

		ret = 0;

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

		if (!cpuidle_curr_governor ||

include/linux/cpuidle.h

+3 −0
Original line number Diff line number Diff line
@@ -121,6 +121,9 @@ struct cpuidle_driver { 


	/* the driver handles the cpus in cpumask */

	struct cpumask		*cpumask;



	/* preferred governor to switch at register time */

	const char		*governor;

};



#ifdef CONFIG_CPU_IDLE

CRA Git | Maintained and supported by SUSTech CRA and CCSE