[RFC PATCH V2 4/4] Single/Global registration of idle states

From: Trinabh Gupta
Date: Mon Apr 11 2011 - 03:17:57 EST

With this patch there is single copy of cpuidle_states structure
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 driverand
architectures such as POWER do not have asymmetric C-states.

To Do:

1. Handle the case when idle states may change at run time
and acpi_processor_cst_has_changed() routine is called.

2. Handle acpi_processor_power_exit() correctly i.e. ensure
unregistration of cpuidle driver since registration is now
moved inside acpi_processor_power_init().


Signed-off-by: Trinabh Gupta <trinabh@xxxxxxxxxxxxxxxxxx>
---

drivers/acpi/processor_driver.c | 18 +-----
drivers/acpi/processor_idle.c | 117 +++++++++++++++++++++++++++++++-------
drivers/cpuidle/cpuidle.c | 42 ++++----------
drivers/cpuidle/driver.c | 25 ++++++++
drivers/cpuidle/governors/menu.c | 16 +++--
drivers/cpuidle/sysfs.c | 3 +
include/linux/cpuidle.h | 16 ++++-
7 files changed, 156 insertions(+), 81 deletions(-)

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index a4e0f1b..91464b4 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -503,8 +503,7 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
acpi_processor_get_throttling_info(pr);
acpi_processor_get_limit_info(pr);

-
- if (cpuidle_get_driver() == &acpi_idle_driver)
+ if (!cpuidle_get_driver() || cpuidle_get_driver() == &acpi_idle_driver)
acpi_processor_power_init(pr, device);

pr->cdev = thermal_cooling_device_register("Processor", device,
@@ -800,17 +799,9 @@ static int __init acpi_processor_init(void)

memset(&errata, 0, sizeof(errata));

- if (!cpuidle_register_driver(&acpi_idle_driver)) {
- printk(KERN_DEBUG "ACPI: %s registered with cpuidle\n",
- acpi_idle_driver.name);
- } else {
- printk(KERN_DEBUG "ACPI: acpi_idle yielding to %s\n",
- cpuidle_get_driver()->name);
- }
-
result = acpi_bus_register_driver(&acpi_processor_driver);
if (result < 0)
- goto out_cpuidle;
+ return result;

acpi_processor_install_hotplug_notify();

@@ -821,11 +812,6 @@ static int __init acpi_processor_init(void)
acpi_processor_throttling_init();

return 0;
-
-out_cpuidle:
- cpuidle_unregister_driver(&acpi_idle_driver);
-
- return result;
}

static void __exit acpi_processor_exit(void)
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index bd29363..505355d 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -741,11 +741,13 @@ static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
/**
* acpi_idle_enter_c1 - enters an ACPI C1 state-type
* @dev: the target CPU
+ * @drv: cpuidle driver containing cpuidle state info
* @index: index of target state
*
* This is equivalent to the HALT instruction.
*/
-static int acpi_idle_enter_c1(struct cpuidle_device *dev, int index)
+static int acpi_idle_enter_c1(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
{
ktime_t kt1, kt2;
s64 idle_time;
@@ -789,9 +791,11 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev, int index)
/**
* acpi_idle_enter_simple - enters an ACPI state without BM handling
* @dev: the target CPU
+ * @drv: cpuidle driver with cpuidle state information
* @index: the index of suggested state
*/
-static int acpi_idle_enter_simple(struct cpuidle_device *dev, int index)
+static int acpi_idle_enter_simple(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
{
struct acpi_processor *pr;
struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
@@ -873,11 +877,13 @@ static DEFINE_SPINLOCK(c3_lock);
/**
* acpi_idle_enter_bm - enters C3 with proper BM handling
* @dev: the target CPU
+ * @drv: cpuidle driver containing state data
* @index: the index of suggested state
*
* If BM is detected, the deepest non-C3 idle state is entered instead.
*/
-static int acpi_idle_enter_bm(struct cpuidle_device *dev, int index)
+static int acpi_idle_enter_bm(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
{
struct acpi_processor *pr;
struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
@@ -900,9 +906,9 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev, int index)
}

if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
- if (dev->safe_state_index >= 0) {
- return dev->states[dev->safe_state_index].enter(dev,
- dev->safe_state_index);
+ if (drv->safe_state_index >= 0) {
+ return drv->states[drv->safe_state_index].enter(dev,
+ drv, drv->safe_state_index);
} else {
local_irq_disable();
acpi_safe_halt();
@@ -999,14 +1005,15 @@ struct cpuidle_driver acpi_idle_driver = {
};

/**
- * acpi_processor_setup_cpuidle - prepares and configures CPUIDLE
+ * acpi_processor_setup_cpuidle_cx - prepares and configures CPUIDLE
+ * device i.e. per-cpu data
+ *
* @pr: the ACPI processor
*/
-static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
+static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr)
{
int i, count = CPUIDLE_DRIVER_STATE_START;
struct acpi_processor_cx *cx;
- struct cpuidle_state *state;
struct cpuidle_state_usage *state_usage;
struct cpuidle_device *dev = &pr->power.dev;

@@ -1018,18 +1025,12 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
}

dev->cpu = pr->id;
- dev->safe_state_index = -1;
- for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
- dev->states[i].name[0] = '\0';
- dev->states[i].desc[0] = '\0';
- }

if (max_cstate == 0)
max_cstate = 1;

for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
cx = &pr->power.states[i];
- state = &dev->states[count];
state_usage = &dev->states_usage[count];

if (!cx->valid)
@@ -1041,8 +1042,61 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
!(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
continue;
#endif
+
cpuidle_set_statedata(state_usage, cx);

+ count++;
+ if (count == CPUIDLE_STATE_MAX)
+ break;
+ }
+
+ dev->state_count = count;
+
+ if (!count)
+ return -EINVAL;
+
+ return 0;
+}
+
+/**
+ * acpi_processor_setup_cpuidle states- prepares and configures cpuidle
+ * global state data i.e. idle routines
+ *
+ * @pr: the ACPI processor
+ */
+static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
+{
+ int i, count = CPUIDLE_DRIVER_STATE_START;
+ struct acpi_processor_cx *cx;
+ struct cpuidle_state *state;
+ struct cpuidle_driver *drv = &acpi_idle_driver;
+
+ if (!pr->flags.power_setup_done)
+ return -EINVAL;
+
+ if (pr->flags.power == 0) {
+ return -EINVAL;
+ }
+
+ drv->safe_state_index = -1;
+
+ if (max_cstate == 0)
+ max_cstate = 1;
+
+ for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
+ cx = &pr->power.states[i];
+
+ if (!cx->valid)
+ continue;
+
+#ifdef CONFIG_HOTPLUG_CPU
+ if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
+ !pr->flags.has_cst &&
+ !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
+ continue;
+#endif
+
+ state = &drv->states[count];
snprintf(state->name, CPUIDLE_NAME_LEN, "C%d", i);
strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
state->exit_latency = cx->latency;
@@ -1055,13 +1109,13 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
state->flags |= CPUIDLE_FLAG_TIME_VALID;

state->enter = acpi_idle_enter_c1;
- dev->safe_state_index = count;
+ drv->safe_state_index = count;
break;

case ACPI_STATE_C2:
state->flags |= CPUIDLE_FLAG_TIME_VALID;
state->enter = acpi_idle_enter_simple;
- dev->safe_state_index = count;
+ drv->safe_state_index = count;
break;

case ACPI_STATE_C3:
@@ -1077,7 +1131,7 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
break;
}

- dev->state_count = count;
+ drv->state_count = count;

if (!count)
return -EINVAL;
@@ -1106,7 +1160,15 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr)
cpuidle_disable_device(&pr->power.dev);
acpi_processor_get_power_info(pr);
if (pr->flags.power) {
- acpi_processor_setup_cpuidle(pr);
+ /*
+ * To Do: Currently state data within driver
+ * is not updated. So change this to also update
+ * actual state data i.e. what this routine is
+ * meant for. Maybe complete unregistration and
+ * re-registration.
+ *
+ */
+ acpi_processor_setup_cpuidle_cx(pr);
ret = cpuidle_enable_device(&pr->power.dev);
}
cpuidle_resume_and_unlock();
@@ -1118,7 +1180,7 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
struct acpi_device *device)
{
acpi_status status = 0;
- static int first_run;
+ static int first_run, acpi_processor_registered;

if (disabled_by_idle_boot_param())
return 0;
@@ -1154,7 +1216,15 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
* platforms that only support C1.
*/
if (pr->flags.power) {
- acpi_processor_setup_cpuidle(pr);
+ if (!acpi_processor_registered) {
+ acpi_processor_setup_cpuidle_states(pr);
+ if (!cpuidle_register_driver(&acpi_idle_driver)) {
+ printk(KERN_DEBUG "ACPI: %s registered with cpuidle\n",
+ acpi_idle_driver.name);
+ acpi_processor_registered = 1;
+ }
+ }
+ acpi_processor_setup_cpuidle_cx(pr);
if (cpuidle_register_device(&pr->power.dev))
return -EIO;
}
@@ -1168,6 +1238,11 @@ int acpi_processor_power_exit(struct acpi_processor *pr,
return 0;

cpuidle_unregister_device(&pr->power.dev);
+ /* We will have to have unregister driver as well here
+ * since we move register_driver to power_init. Maybe
+ * just do an unregister everytime; which will be successful
+ * only during the last call.
+ */
pr->flags.power_setup_done = 0;

return 0;
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 5d6f98d..69c5de5 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -50,6 +50,7 @@ static int __cpuidle_register_device(struct cpuidle_device *dev);
static void 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;

@@ -76,19 +77,19 @@ static void 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;
}

- target_state = &dev->states[next_state];
+ target_state = &drv->states[next_state];

/* Is using next_state here correct?? */
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);
@@ -144,7 +145,8 @@ 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;
@@ -167,12 +169,9 @@ 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");
@@ -183,7 +182,7 @@ 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 */

/**
@@ -210,7 +209,8 @@ int cpuidle_enable_device(struct cpuidle_device *dev)
return ret;
}

- poll_idle_init(dev);
+ poll_idle_init(cpuidle_get_driver());
+ cpuidle_set_statedata(&dev->states_usage[0], NULL);

if ((ret = cpuidle_add_state_sysfs(dev)))
return ret;
@@ -285,26 +285,6 @@ 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))) {
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index fd1601e..4b04129 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -17,6 +17,30 @@
static struct cpuidle_driver *cpuidle_curr_driver;
DEFINE_SPINLOCK(cpuidle_driver_lock);

+static void __cpuidle_register_driver(struct cpuidle_driver *drv)
+{
+ /*
+ * cpuidle driver should set the drv->power_specified bit
+ * before registering if the driver provides
+ * power_usage numbers.
+ *
+ * If 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 (!drv->power_specified) {
+ int i;
+ for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++)
+ drv->states[i].power_usage = -1 - i;
+ }
+}
+
+
/**
* cpuidle_register_driver - registers a driver
* @drv: the driver
@@ -31,6 +55,7 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
spin_unlock(&cpuidle_driver_lock);
return -EBUSY;
}
+ __cpuidle_register_driver(drv);
cpuidle_curr_driver = drv;
spin_unlock(&cpuidle_driver_lock);

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 40b5630..44651ae 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -182,7 +182,7 @@ static inline int performance_multiplier(void)

static DEFINE_PER_CPU(struct menu_device, menu_devices);

-static void menu_update(struct cpuidle_device *dev);
+static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev);

/* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */
static u64 div_round64(u64 dividend, u32 divisor)
@@ -228,9 +228,10 @@ static void detect_repeating_patterns(struct menu_device *data)

/**
* menu_select - selects the next idle state to enter
+ * @drv: cpuidle driver containing state data
* @dev: the CPU
*/
-static int menu_select(struct cpuidle_device *dev)
+static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
{
struct menu_device *data = &__get_cpu_var(menu_devices);
int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
@@ -239,7 +240,7 @@ static int menu_select(struct cpuidle_device *dev)
int multiplier;

if (data->needs_update) {
- menu_update(dev);
+ menu_update(drv, dev);
data->needs_update = 0;
}

@@ -283,8 +284,8 @@ static int menu_select(struct cpuidle_device *dev)
* Find the idle state with the lowest power while satisfying
* our constraints.
*/
- for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++) {
- struct cpuidle_state *s = &dev->states[i];
+ for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
+ struct cpuidle_state *s = &drv->states[i];

if (s->target_residency > data->predicted_us)
continue;
@@ -321,14 +322,15 @@ static void menu_reflect(struct cpuidle_device *dev, int index)

/**
* menu_update - attempts to guess what happened after entry
+ * @drv: cpuidle driver containing state data
* @dev: the CPU
*/
-static void menu_update(struct cpuidle_device *dev)
+static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
{
struct menu_device *data = &__get_cpu_var(menu_devices);
int last_idx = data->last_state_idx;
unsigned int last_idle_us = cpuidle_get_last_residency(dev);
- struct cpuidle_state *target = &dev->states[last_idx];
+ struct cpuidle_state *target = &drv->states[last_idx];
unsigned int measured_us;
u64 new_factor;

diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index 09c9c77..90be2ad 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -318,13 +318,14 @@ int cpuidle_add_state_sysfs(struct cpuidle_device *device)
{
int i, ret = -ENOMEM;
struct cpuidle_state_kobj *kobj;
+ struct cpuidle_driver *drv = cpuidle_get_driver();

/* state statistics */
for (i = 0; i < device->state_count; i++) {
kobj = kzalloc(sizeof(struct cpuidle_state_kobj), GFP_KERNEL);
if (!kobj)
goto error_state;
- kobj->state = &device->states[i];
+ kobj->state = &drv->states[i];
kobj->state_usage = &device->states_usage[i];
init_completion(&kobj->kobj_unregister);

diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 5a1a238..0964f21 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -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);
};

@@ -83,20 +85,17 @@ 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];

- struct list_head device_list;
+ struct list_head device_list;
struct kobject kobj;
struct completion kobj_unregister;
void *governor_data;
- int safe_state_index;
};

DECLARE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
@@ -120,6 +119,12 @@ 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;
+ struct cpuidle_state *safe_state;
+ int safe_state_index;
};

#ifdef CONFIG_CPU_IDLE
@@ -165,7 +170,8 @@ struct cpuidle_governor {
int (*enable) (struct cpuidle_device *dev);
void (*disable) (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;

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/