The scheduler uses the idle timestamp stored in the struct rq to retrieve the time when the cpu went idle in order to find the idlest cpu. Unfortunately this information is wrong as it does not have the same meaning from the cpuidle point of view. The idle_stamp in the struct rq gives the information when the idle task has been scheduled while the idle task could be interrupted several times and the cpu going through an idle/wakeup multiple times.
Add the idle start time in the idle state structure. Signed-off-by: Daniel Lezcano <[email protected]> --- drivers/cpuidle/cpuidle.c | 10 ++++++---- include/linux/cpuidle.h | 1 + 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 080bd2d..1220dac 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -158,21 +158,23 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, int entered_state; struct cpuidle_state *target_state = &drv->states[index]; - ktime_t time_start, time_end; s64 diff; trace_cpu_idle_rcuidle(index, dev->cpu); - time_start = ktime_get(); + + target_state->idle_stamp = ktime_to_us(ktime_get()); entered_state = target_state->enter(dev, drv, index); - time_end = ktime_get(); + diff = ktime_to_us(ktime_sub_us(ktime_get(), target_state->idle_stamp)); + + target_state->idle_stamp = 0; + trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); if (!cpuidle_state_is_coupled(dev, drv, entered_state)) local_irq_enable(); - diff = ktime_to_us(ktime_sub(time_end, time_start)); if (diff > INT_MAX) diff = INT_MAX; diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index 306178d..2facce6 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -44,6 +44,7 @@ struct cpuidle_state { int power_usage; /* in mW */ unsigned int target_residency; /* in US */ bool disabled; /* disabled on all CPUs */ + u64 idle_stamp; int (*enter) (struct cpuidle_device *dev, struct cpuidle_driver *drv, -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
