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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
parenta093b93ee0e08cd73a07848752bc09ecea68cb13 (diff)
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>
-rw-r--r--arch/powerpc/platforms/pseries/processor_idle.c4
-rw-r--r--drivers/acpi/processor_idle.c57
-rw-r--r--drivers/cpuidle/cpuidle.c3
-rw-r--r--drivers/idle/intel_idle.c14
4 files changed, 7 insertions, 71 deletions
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c
index 45d00e5fe14d..4d806b419606 100644
--- a/arch/powerpc/platforms/pseries/processor_idle.c
+++ b/arch/powerpc/platforms/pseries/processor_idle.c
@@ -36,7 +36,7 @@ static struct cpuidle_state *cpuidle_state_table;
static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t *kt_before)
{
- *kt_before = ktime_get_real();
+ *kt_before = ktime_get();
*in_purr = mfspr(SPRN_PURR);
/*
* Indicate to the HV that we are idle. Now would be
@@ -50,7 +50,7 @@ static inline s64 idle_loop_epilog(unsigned long in_purr, ktime_t kt_before)
get_lppaca()->wait_state_cycles += mfspr(SPRN_PURR) - in_purr;
get_lppaca()->idle = 0;
- return ktime_to_us(ktime_sub(ktime_get_real(), kt_before));
+ return ktime_to_us(ktime_sub(ktime_get(), kt_before));
}
static int snooze_loop(struct cpuidle_device *dev,
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,
};
/**
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 711dd83fd3ba..8df53dd8dbe1 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -109,8 +109,7 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
/* This can be moved to within driver enter routine
* but that results in multiple copies of same code.
*/
- dev->states_usage[entered_state].time +=
- (unsigned long long)dev->last_residency;
+ dev->states_usage[entered_state].time += dev->last_residency;
dev->states_usage[entered_state].usage++;
} else {
dev->last_residency = 0;
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index b0f6b4c8ee14..c49c04d9c2b0 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -56,7 +56,6 @@
#include <linux/kernel.h>
#include <linux/cpuidle.h>
#include <linux/clockchips.h>
-#include <linux/hrtimer.h> /* ktime_get_real() */
#include <trace/events/power.h>
#include <linux/sched.h>
#include <linux/notifier.h>
@@ -72,6 +71,7 @@
static struct cpuidle_driver intel_idle_driver = {
.name = "intel_idle",
.owner = THIS_MODULE,
+ .en_core_tk_irqen = 1,
};
/* intel_idle.max_cstate=0 disables driver */
static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
@@ -281,8 +281,6 @@ static int intel_idle(struct cpuidle_device *dev,
struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
unsigned long eax = (unsigned long)cpuidle_get_statedata(state_usage);
unsigned int cstate;
- ktime_t kt_before, kt_after;
- s64 usec_delta;
int cpu = smp_processor_id();
cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
@@ -297,8 +295,6 @@ static int intel_idle(struct cpuidle_device *dev,
if (!(lapic_timer_reliable_states & (1 << (cstate))))
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
- kt_before = ktime_get_real();
-
stop_critical_timings();
if (!need_resched()) {
@@ -310,17 +306,9 @@ static int intel_idle(struct cpuidle_device *dev,
start_critical_timings();
- kt_after = ktime_get_real();
- usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before));
-
- local_irq_enable();
-
if (!(lapic_timer_reliable_states & (1 << (cstate))))
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
- /* Update cpuidle counters */
- dev->last_residency = (int)usec_delta;
-
return index;
}