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Subject[PATCH] Revert "cpuidle: Replace ktime_get() with local_clock()"
From: Ville Syrjälä <>

This reverts commit e93e59ce5b85e6c2b444f09fd1f707274ec066dc.

The TSC stops in deeper C states, so using local_clock() in cpuidle
to track the C state residency seems like a bad idea. With local_clock()
powertop is reporting mostly 0% residency for C states here. Presumably
the core is still spending most of its time in some deep C-state since
the totals typically add up to only 5% or so, so perhaps the governor
isn't getting totally confused by these bogus numbers. But let's go
back to using ktime_get() as that at least works correctly across the

Note that the code has changed somewhat since the regression happened,
so this isn't a 1:1 revert of the offending commit.

Cc: Daniel Lezcano <>
Cc: Peter Zijlstra (Intel) <>
Cc: Rafael J. Wysocki <>
Signed-off-by: Ville Syrjälä <>
drivers/cpuidle/cpuidle.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 548b90be7685..24a52805527f 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -213,13 +213,13 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,

trace_cpu_idle_rcuidle(index, dev->cpu);
- time_start = ns_to_ktime(local_clock());
+ time_start = ktime_get();

entered_state = target_state->enter(dev, drv, index);

- time_end = ns_to_ktime(local_clock());
+ time_end = ktime_get();
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);

/* The cpu is no longer idle or about to enter idle. */
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