@@ -5,6 +5,7 @@
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/cpuhotplug.h>
+#include <linux/cpu_pm.h>
#include <linux/tick.h>
#include <linux/mm.h>
#include <linux/stackprotector.h>
@@ -130,6 +131,7 @@ static void cpuidle_idle_call(void)
struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
int next_state, entered_state;
+ int ret;
/*
* Check if the idle task must be rescheduled. If it is the
@@ -174,12 +176,16 @@ static void cpuidle_idle_call(void)
/*
* Ask the cpuidle framework to choose a convenient idle state.
*/
- next_state = cpuidle_select(drv, dev);
- entered_state = call_cpuidle(drv, dev, next_state);
- /*
- * Give the governor an opportunity to reflect on the outcome
- */
- cpuidle_reflect(dev, entered_state);
+ ret = cpu_pm_enter();
+ if (!ret) {
+ next_state = cpuidle_select(drv, dev);
+ entered_state = call_cpuidle(drv, dev, next_state);
+ cpu_pm_exit();
+ /*
+ * Give the governor an opportunity to reflect on the outcome
+ */
+ cpuidle_reflect(dev, entered_state);
+ }
}
exit_idle:
In previous version, cpu_pm_enter is invoked after the governor select the state, which cause the executing time of cpu_pm_enter is included in the idle time. Moving it before the state selection. Please refer to bellowing chart for detailed information current approach: static void cpu_idle_loop(void) { while (1) { tick_nohz_idle_enter(); --->__tick_nohz_idle_enter --->tick_nohz_stop_sched_tick { ... ts->sleep_length = ktime_sub(dev->next_event, now); /*1*/ ... } while (!need_resched()) { ... local_irq_disable(); arch_cpu_idle_enter(); --->idle_notifier_call_chain(IDLE_START); /*2*/ cpuidle_idle_call(); --->next_state = cpuidle_select(drv, dev); /*3*/ --->static int arm_enter_idle_state(...) { ... ret = cpu_pm_enter(); /*4*/ } } ---------|----------------------|----------------------------|------------------------------------|--------------------------------------------|-------------------- 1.now 2.IDLE_START 3.select idle state 4.CPU_PM_ENTER next_event (sleep_length) modified approach: static void cpu_idle_loop(void) { while (1) { tick_nohz_idle_enter(); --->__tick_nohz_idle_enter --->tick_nohz_stop_sched_tick { ... ... } while (!need_resched()) { ... local_irq_disable(); arch_cpu_idle_enter(); --->idle_notifier_call_chain(IDLE_START); /*1*/ cpuidle_idle_call(); --->ret = cpu_pm_enter(); /*2*/ --->tick_nohz_get_sleep_length { ts->sleep_length = ktime_sub(dev->next_event, now); /*3*/ } --->next_state = cpuidle_select(drv, dev); /*4*/ --->static int arm_enter_idle_state(...) } ----------------|---------------------------------------|---------------------|------------------|--------------------------------------------|-------------------- 1.IDLE_START 2.CPU_PM_ENTER 3.now 4.select idle state next_event (sleep_length) Signed-off-by: Zhaoyang Huang <zhaoyang.huang@spreadtrum.com> --- kernel/sched/idle.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html