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cpuidle: Single/Global registration of idle states

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This patch makes the cpuidle_states structure global (single copy)
instead of per-cpu. The statistics needed on per-cpu basis
by the governor are kept per-cpu. This simplifies the cpuidle
subsystem as state registration is done by single cpu only.
Having single copy of cpuidle_states saves memory. Rare case
of asymmetric C-states can be handled within the cpuidle driver
and architectures such as POWER do not have asymmetric C-states.

Having single/global registration of all the idle states,
dynamic C-state transitions on x86 are handled by
the boot cpu. Here, the boot cpu  would disable all the devices,
re-populate the states and later enable all the devices,
irrespective of the cpu that would receive the notification first.

Reference:
https://lkml.org/lkml/2011/4/25/83

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Trinabh Gupta <g.trinabh@gmail.com>
Tested-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Deepthi Dharwar 2011-10-28 16:20:42 +05:30 • committed by Len Brown
parent 4202735e8a
commit 46bcfad7a8
16 changed files with 438 additions and 206 deletions
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19
include/linux/cpuidle.h
View file

@ -22,6 +22,7 @@
#define CPUIDLE_DESC_LEN 32
struct cpuidle_device;
struct cpuidle_driver;
/****************************
@ -45,6 +46,7 @@ struct cpuidle_state {
unsigned int target_residency; /* in US */
int (*enter) (struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index);
};
@ -83,12 +85,10 @@ struct cpuidle_state_kobj {
struct cpuidle_device {
unsigned int registered:1;
unsigned int enabled:1;
unsigned int power_specified:1;
unsigned int cpu;
int last_residency;
int state_count;
struct cpuidle_state states[CPUIDLE_STATE_MAX];
struct cpuidle_state_usage states_usage[CPUIDLE_STATE_MAX];
struct cpuidle_state_kobj *kobjs[CPUIDLE_STATE_MAX];
@ -96,7 +96,6 @@ struct cpuidle_device {
struct kobject kobj;
struct completion kobj_unregister;
void *governor_data;
int safe_state_index;
};
DECLARE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
@ -120,6 +119,11 @@ static inline int cpuidle_get_last_residency(struct cpuidle_device *dev)
struct cpuidle_driver {
char name[CPUIDLE_NAME_LEN];
struct module *owner;
unsigned int power_specified:1;
struct cpuidle_state states[CPUIDLE_STATE_MAX];
int state_count;
int safe_state_index;
};
#ifdef CONFIG_CPU_IDLE
@ -166,10 +170,13 @@ struct cpuidle_governor {
struct list_head governor_list;
unsigned int rating;
int (*enable) (struct cpuidle_device *dev);
void (*disable) (struct cpuidle_device *dev);
int (*enable) (struct cpuidle_driver *drv,
struct cpuidle_device *dev);
void (*disable) (struct cpuidle_driver *drv,
struct cpuidle_device *dev);
int (*select) (struct cpuidle_device *dev);
int (*select) (struct cpuidle_driver *drv,
struct cpuidle_device *dev);
void (*reflect) (struct cpuidle_device *dev, int index);
struct module *owner;