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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
Download Patch File Download Diff File Expand all files Collapse all files

45
drivers/cpuidle/cpuidle.c
View File

@@ -61,6 +61,7 @@ static int __cpuidle_register_device(struct cpuidle_device *dev);
int cpuidle_idle_call(void)
{
struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
struct cpuidle_driver *drv = cpuidle_get_driver();
struct cpuidle_state *target_state;
int next_state, entered_state;
@@ -84,18 +85,18 @@ int cpuidle_idle_call(void)
#endif
/* ask the governor for the next state */
next_state = cpuidle_curr_governor->select(dev);
next_state = cpuidle_curr_governor->select(drv, dev);
if (need_resched()) {
local_irq_enable();
return 0;
}
target_state = &dev->states[next_state];
target_state = &drv->states[next_state];
trace_power_start(POWER_CSTATE, next_state, dev->cpu);
trace_cpu_idle(next_state, dev->cpu);
entered_state = target_state->enter(dev, next_state);
entered_state = target_state->enter(dev, drv, next_state);
trace_power_end(dev->cpu);
trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
@@ -163,7 +164,8 @@ void cpuidle_resume_and_unlock(void)
EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
#ifdef CONFIG_ARCH_HAS_CPU_RELAX
static int poll_idle(struct cpuidle_device *dev, int index)
static int poll_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
ktime_t t1, t2;
s64 diff;
@@ -183,12 +185,9 @@ static int poll_idle(struct cpuidle_device *dev, int index)
return index;
}
static void poll_idle_init(struct cpuidle_device *dev)
static void poll_idle_init(struct cpuidle_driver *drv)
{
struct cpuidle_state *state = &dev->states[0];
struct cpuidle_state_usage *state_usage = &dev->states_usage[0];
cpuidle_set_statedata(state_usage, NULL);
struct cpuidle_state *state = &drv->states[0];
snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
@@ -199,7 +198,7 @@ static void poll_idle_init(struct cpuidle_device *dev)
state->enter = poll_idle;
}
#else
static void poll_idle_init(struct cpuidle_device *dev) {}
static void poll_idle_init(struct cpuidle_driver *drv) {}
#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
/**
@@ -226,13 +225,13 @@ int cpuidle_enable_device(struct cpuidle_device *dev)
return ret;
}
poll_idle_init(dev);
poll_idle_init(cpuidle_get_driver());
if ((ret = cpuidle_add_state_sysfs(dev)))
return ret;
if (cpuidle_curr_governor->enable &&
(ret = cpuidle_curr_governor->enable(dev)))
(ret = cpuidle_curr_governor->enable(cpuidle_get_driver(), dev)))
goto fail_sysfs;
for (i = 0; i < dev->state_count; i++) {
@@ -273,7 +272,7 @@ void cpuidle_disable_device(struct cpuidle_device *dev)
dev->enabled = 0;
if (cpuidle_curr_governor->disable)
cpuidle_curr_governor->disable(dev);
cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
cpuidle_remove_state_sysfs(dev);
enabled_devices--;
@@ -301,26 +300,6 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
init_completion(&dev->kobj_unregister);
/*
* cpuidle driver should set the dev->power_specified bit
* before registering the device if the driver provides
* power_usage numbers.
*
* For those devices whose ->power_specified is not set,
* we fill in power_usage with decreasing values as the
* cpuidle code has an implicit assumption that state Cn
* uses less power than C(n-1).
*
* With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
* an power value of -1. So we use -2, -3, etc, for other
* c-states.
*/
if (!dev->power_specified) {
int i;
for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++)
dev->states[i].power_usage = -1 - i;
}
per_cpu(cpuidle_devices, dev->cpu) = dev;
list_add(&dev->device_list, &cpuidle_detected_devices);
if ((ret = cpuidle_add_sysfs(sys_dev))) {