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cpuidle: allow governor switch on cpuidle_register_driver()

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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: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Joao Martins 2019-09-08 00:45:21 +01:00 committed by Rafael J. Wysocki
parent cd4c076306
commit cb5d8c45ab
4 changed files with 34 additions and 3 deletions
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2
drivers/cpuidle/cpuidle.h
View File

@ -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 */

25
drivers/cpuidle/driver.c
View File

@ -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);

7
drivers/cpuidle/governor.c
View File

@ -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 ||

3
include/linux/cpuidle.h
View File

@ -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