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authorJulius Werner <jwerner@chromium.org>2012-11-27 14:17:58 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2012-11-27 14:17:58 +0100
commita474a515497ef3566cfc17a2cab3d54d6d50ff1c (patch)
tree377b53565f728dfee5604ae0c8c6879d38a2a3ec /drivers/acpi
parenta093b93ee0e08cd73a07848752bc09ecea68cb13 (diff)
downloadlinux-a474a515497ef3566cfc17a2cab3d54d6d50ff1c.tar.bz2
cpuidle: Measure idle state durations with monotonic clock
Many cpuidle drivers measure their time spent in an idle state by reading the wallclock time before and after idling and calculating the difference. This leads to erroneous results when the wallclock time gets updated by another processor in the meantime, adding that clock adjustment to the idle state's time counter. If the clock adjustment was negative, the result is even worse due to an erroneous cast from int to unsigned long long of the last_residency variable. The negative 32 bit integer will zero-extend and result in a forward time jump of roughly four billion milliseconds or 1.3 hours on the idle state residency counter. This patch changes all affected cpuidle drivers to either use the monotonic clock for their measurements or make use of the generic time measurement wrapper in cpuidle.c, which was already working correctly. Some superfluous CLIs/STIs in the ACPI code are removed (interrupts should always already be disabled before entering the idle function, and not get reenabled until the generic wrapper has performed its second measurement). It also removes the erroneous cast, making sure that negative residency values are applied correctly even though they should not appear anymore. Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Len Brown <len.brown@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/processor_idle.c57
1 files changed, 3 insertions, 54 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index e8086c725305..f1a5da44591d 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -735,31 +735,18 @@ static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
static int acpi_idle_enter_c1(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
- ktime_t kt1, kt2;
- s64 idle_time;
struct acpi_processor *pr;
struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
pr = __this_cpu_read(processors);
- dev->last_residency = 0;
if (unlikely(!pr))
return -EINVAL;
- local_irq_disable();
-
-
lapic_timer_state_broadcast(pr, cx, 1);
- kt1 = ktime_get_real();
acpi_idle_do_entry(cx);
- kt2 = ktime_get_real();
- idle_time = ktime_to_us(ktime_sub(kt2, kt1));
-
- /* Update device last_residency*/
- dev->last_residency = (int)idle_time;
- local_irq_enable();
lapic_timer_state_broadcast(pr, cx, 0);
return index;
@@ -806,19 +793,12 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
struct acpi_processor *pr;
struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
- ktime_t kt1, kt2;
- s64 idle_time_ns;
- s64 idle_time;
pr = __this_cpu_read(processors);
- dev->last_residency = 0;
if (unlikely(!pr))
return -EINVAL;
- local_irq_disable();
-
-
if (cx->entry_method != ACPI_CSTATE_FFH) {
current_thread_info()->status &= ~TS_POLLING;
/*
@@ -829,7 +809,6 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
if (unlikely(need_resched())) {
current_thread_info()->status |= TS_POLLING;
- local_irq_enable();
return -EINVAL;
}
}
@@ -843,22 +822,12 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
if (cx->type == ACPI_STATE_C3)
ACPI_FLUSH_CPU_CACHE();
- kt1 = ktime_get_real();
/* Tell the scheduler that we are going deep-idle: */
sched_clock_idle_sleep_event();
acpi_idle_do_entry(cx);
- kt2 = ktime_get_real();
- idle_time_ns = ktime_to_ns(ktime_sub(kt2, kt1));
- idle_time = idle_time_ns;
- do_div(idle_time, NSEC_PER_USEC);
- /* Update device last_residency*/
- dev->last_residency = (int)idle_time;
+ sched_clock_idle_wakeup_event(0);
- /* Tell the scheduler how much we idled: */
- sched_clock_idle_wakeup_event(idle_time_ns);
-
- local_irq_enable();
if (cx->entry_method != ACPI_CSTATE_FFH)
current_thread_info()->status |= TS_POLLING;
@@ -883,13 +852,8 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
struct acpi_processor *pr;
struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
- ktime_t kt1, kt2;
- s64 idle_time_ns;
- s64 idle_time;
-
pr = __this_cpu_read(processors);
- dev->last_residency = 0;
if (unlikely(!pr))
return -EINVAL;
@@ -899,16 +863,11 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
return drv->states[drv->safe_state_index].enter(dev,
drv, drv->safe_state_index);
} else {
- local_irq_disable();
acpi_safe_halt();
- local_irq_enable();
return -EBUSY;
}
}
- local_irq_disable();
-
-
if (cx->entry_method != ACPI_CSTATE_FFH) {
current_thread_info()->status &= ~TS_POLLING;
/*
@@ -919,7 +878,6 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
if (unlikely(need_resched())) {
current_thread_info()->status |= TS_POLLING;
- local_irq_enable();
return -EINVAL;
}
}
@@ -934,7 +892,6 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
*/
lapic_timer_state_broadcast(pr, cx, 1);
- kt1 = ktime_get_real();
/*
* disable bus master
* bm_check implies we need ARB_DIS
@@ -965,18 +922,9 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
c3_cpu_count--;
raw_spin_unlock(&c3_lock);
}
- kt2 = ktime_get_real();
- idle_time_ns = ktime_to_ns(ktime_sub(kt2, kt1));
- idle_time = idle_time_ns;
- do_div(idle_time, NSEC_PER_USEC);
-
- /* Update device last_residency*/
- dev->last_residency = (int)idle_time;
- /* Tell the scheduler how much we idled: */
- sched_clock_idle_wakeup_event(idle_time_ns);
+ sched_clock_idle_wakeup_event(0);
- local_irq_enable();
if (cx->entry_method != ACPI_CSTATE_FFH)
current_thread_info()->status |= TS_POLLING;
@@ -987,6 +935,7 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
struct cpuidle_driver acpi_idle_driver = {
.name = "acpi_idle",
.owner = THIS_MODULE,
+ .en_core_tk_irqen = 1,
};
/**