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authorvenkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com>2008-07-30 19:21:42 -0700
committerAndi Kleen <ak@linux.intel.com>2008-08-15 21:25:25 +0200
commita2bd92023357e47f22a34d4cb1635453546662bc (patch)
tree7bd9df24a4dc5ce24f944c1d70e0d96fcd0dc882 /drivers
parentb635acec48bcaa9183fcbf4e3955616b0d4119b5 (diff)
cpuidle: Do not use poll_idle unless user asks for it
poll_idle was added to CPUIDLE, just as a low latency idle handler, to be used in cases when user desires CPUs not to enter any idle state at all. It was supposed to be a run time idle=poll option to the user. But, it was indeed getting used during normal menu and ladder governor default case, with no special user setting (Reported by Linus Torvalds). Change below ensures that poll_idle will not be used unless user explicitly asks pm_qos infrastructure for zero latency requirement. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/cpuidle/governors/ladder.c14
-rw-r--r--drivers/cpuidle/governors/menu.c11
2 files changed, 19 insertions, 6 deletions
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index ba7b9a6b17a..27ab3bfe375 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -67,10 +67,17 @@ static int ladder_select_state(struct cpuidle_device *dev)
struct ladder_device *ldev = &__get_cpu_var(ladder_devices);
struct ladder_device_state *last_state;
int last_residency, last_idx = ldev->last_state_idx;
+ int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
if (unlikely(!ldev))
return 0;
+ /* Special case when user has set very strict latency requirement */
+ if (unlikely(latency_req == 0)) {
+ ladder_do_selection(ldev, last_idx, 0);
+ return 0;
+ }
+
last_state = &ldev->states[last_idx];
if (dev->states[last_idx].flags & CPUIDLE_FLAG_TIME_VALID)
@@ -81,8 +88,7 @@ static int ladder_select_state(struct cpuidle_device *dev)
/* consider promotion */
if (last_idx < dev->state_count - 1 &&
last_residency > last_state->threshold.promotion_time &&
- dev->states[last_idx + 1].exit_latency <=
- pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY)) {
+ dev->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) {
@@ -92,7 +98,7 @@ static int ladder_select_state(struct cpuidle_device *dev)
}
/* consider demotion */
- if (last_idx > 0 &&
+ if (last_idx > CPUIDLE_DRIVER_STATE_START &&
last_residency < last_state->threshold.demotion_time) {
last_state->stats.demotion_count++;
last_state->stats.promotion_count = 0;
@@ -117,7 +123,7 @@ static int ladder_enable_device(struct cpuidle_device *dev)
struct ladder_device_state *lstate;
struct cpuidle_state *state;
- ldev->last_state_idx = 0;
+ ldev->last_state_idx = CPUIDLE_DRIVER_STATE_START;
for (i = 0; i < dev->state_count; i++) {
state = &dev->states[i];
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 78d77c5dc35..b8f3e21530b 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -34,21 +34,28 @@ static DEFINE_PER_CPU(struct menu_device, menu_devices);
static int menu_select(struct cpuidle_device *dev)
{
struct menu_device *data = &__get_cpu_var(menu_devices);
+ int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
int i;
+ /* Special case when user has set very strict latency requirement */
+ if (unlikely(latency_req == 0)) {
+ data->last_state_idx = 0;
+ return 0;
+ }
+
/* determine the expected residency time */
data->expected_us =
(u32) ktime_to_ns(tick_nohz_get_sleep_length()) / 1000;
/* find the deepest idle state that satisfies our constraints */
- for (i = 1; i < dev->state_count; i++) {
+ for (i = CPUIDLE_DRIVER_STATE_START + 1; i < dev->state_count; i++) {
struct cpuidle_state *s = &dev->states[i];
if (s->target_residency > data->expected_us)
break;
if (s->target_residency > data->predicted_us)
break;
- if (s->exit_latency > pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY))
+ if (s->exit_latency > latency_req)
break;
}