Commit-ID: f9fccdb9efef60dbcf84d493514b475c41aa866f
Gitweb: http://git.kernel.org/tip/f9fccdb9efef60dbcf84d493514b475c41aa866f
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 21 Apr 2017 12:43:59 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 15 May 2017 10:15:20 +0200
cpuidle: Fix idle time tracking
Ville reported that on his Core2, which has TSC stop in idle, we would
always report very short idle durations. He tracked this down to
commit:
e93e59ce5b85 ("cpuidle: Replace ktime_get() with local_clock()")
which replaces ktime_get() with local_clock().
Add a sched_clock_idle_wakeup_event() call, which will re-sync the
clock with ktime_get_ns() when TSC is unstable and no-op otherwise.
Reported-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Tested-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rafael J . Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Fixes: e93e59ce5b85 ("cpuidle: Replace ktime_get() with local_clock()")
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
drivers/cpuidle/cpuidle.c | 1 +
kernel/sched/clock.c | 11 +++++++++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 2706be7..60bb64f 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -220,6 +220,7 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
entered_state = target_state->enter(dev, drv, index);
start_critical_timings();
+ sched_clock_idle_wakeup_event();
time_end = ns_to_ktime(local_clock());
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
index c30c05f..d4c2f89 100644
--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -410,14 +410,21 @@ void sched_clock_idle_sleep_event(void)
EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
/*
- * We just idled; resync with ktime. (called with irqs disabled):
+ * We just idled; resync with ktime.
*/
void sched_clock_idle_wakeup_event(void)
{
- if (timekeeping_suspended)
+ unsigned long flags;
+
+ if (sched_clock_stable())
+ return;
+
+ if (unlikely(timekeeping_suspended))
return;
+ local_irq_save(flags);
sched_clock_tick();
+ local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
--
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