cpuidle: Single/Global registration of idle states
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>
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index 6a686a7..ef6b9e4 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -60,9 +60,11 @@
/**
* ladder_select_state - selects the next state to enter
+ * @drv: cpuidle driver
* @dev: the CPU
*/
-static int ladder_select_state(struct cpuidle_device *dev)
+static int ladder_select_state(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
{
struct ladder_device *ldev = &__get_cpu_var(ladder_devices);
struct ladder_device_state *last_state;
@@ -77,15 +79,17 @@
last_state = &ldev->states[last_idx];
- if (dev->states[last_idx].flags & CPUIDLE_FLAG_TIME_VALID)
- last_residency = cpuidle_get_last_residency(dev) - dev->states[last_idx].exit_latency;
+ if (drv->states[last_idx].flags & CPUIDLE_FLAG_TIME_VALID) {
+ last_residency = cpuidle_get_last_residency(dev) - \
+ drv->states[last_idx].exit_latency;
+ }
else
last_residency = last_state->threshold.promotion_time + 1;
/* consider promotion */
- if (last_idx < dev->state_count - 1 &&
+ if (last_idx < drv->state_count - 1 &&
last_residency > last_state->threshold.promotion_time &&
- dev->states[last_idx + 1].exit_latency <= latency_req) {
+ drv->states[last_idx + 1].exit_latency <= latency_req) {
last_state->stats.promotion_count++;
last_state->stats.demotion_count = 0;
if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) {
@@ -96,11 +100,11 @@
/* consider demotion */
if (last_idx > CPUIDLE_DRIVER_STATE_START &&
- dev->states[last_idx].exit_latency > latency_req) {
+ drv->states[last_idx].exit_latency > latency_req) {
int i;
for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) {
- if (dev->states[i].exit_latency <= latency_req)
+ if (drv->states[i].exit_latency <= latency_req)
break;
}
ladder_do_selection(ldev, last_idx, i);
@@ -123,9 +127,11 @@
/**
* ladder_enable_device - setup for the governor
+ * @drv: cpuidle driver
* @dev: the CPU
*/
-static int ladder_enable_device(struct cpuidle_device *dev)
+static int ladder_enable_device(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
{
int i;
struct ladder_device *ldev = &per_cpu(ladder_devices, dev->cpu);
@@ -134,8 +140,8 @@
ldev->last_state_idx = CPUIDLE_DRIVER_STATE_START;
- for (i = 0; i < dev->state_count; i++) {
- state = &dev->states[i];
+ for (i = 0; i < drv->state_count; i++) {
+ state = &drv->states[i];
lstate = &ldev->states[i];
lstate->stats.promotion_count = 0;
@@ -144,7 +150,7 @@
lstate->threshold.promotion_count = PROMOTION_COUNT;
lstate->threshold.demotion_count = DEMOTION_COUNT;
- if (i < dev->state_count - 1)
+ if (i < drv->state_count - 1)
lstate->threshold.promotion_time = state->exit_latency;
if (i > 0)
lstate->threshold.demotion_time = state->exit_latency;