From 0e7767687fdabfc58d5046e7488632bf2ecd4d0c Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Thu, 5 Apr 2018 18:58:27 +0200
Subject: time: tick-sched: Reorganize idle tick management code

Prepare the scheduler tick code for reworking the idle loop to
avoid stopping the tick in some cases.

The idea is to split the nohz idle entry call to decouple the idle
time stats accounting and preparatory work from the actual tick stop
code, in order to later be able to delay the tick stop once we reach
more power-knowledgeable callers.

Move away the tick_nohz_start_idle() invocation from
__tick_nohz_idle_enter(), rename the latter to
__tick_nohz_idle_stop_tick() and define tick_nohz_idle_stop_tick()
as a wrapper around it for calling it from the outside.

Make tick_nohz_idle_enter() only call tick_nohz_start_idle() instead
of calling the entire __tick_nohz_idle_enter(), add another wrapper
disabling and enabling interrupts around tick_nohz_idle_stop_tick()
and make the current callers of tick_nohz_idle_enter() call it too
to retain their current functionality.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/tick.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'include/linux')

diff --git a/include/linux/tick.h b/include/linux/tick.h
index 7f8c9a127f5a..1d253df9ea3c 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -115,6 +115,7 @@ enum tick_dep_bits {
 extern bool tick_nohz_enabled;
 extern bool tick_nohz_tick_stopped(void);
 extern bool tick_nohz_tick_stopped_cpu(int cpu);
+extern void tick_nohz_idle_stop_tick(void);
 extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);
 extern void tick_nohz_irq_exit(void);
@@ -123,10 +124,19 @@ extern unsigned long tick_nohz_get_idle_calls(void);
 extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu);
 extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
 extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
+
+static inline void tick_nohz_idle_stop_tick_protected(void)
+{
+	local_irq_disable();
+	tick_nohz_idle_stop_tick();
+	local_irq_enable();
+}
+
 #else /* !CONFIG_NO_HZ_COMMON */
 #define tick_nohz_enabled (0)
 static inline int tick_nohz_tick_stopped(void) { return 0; }
 static inline int tick_nohz_tick_stopped_cpu(int cpu) { return 0; }
+static inline void tick_nohz_idle_stop_tick(void) { }
 static inline void tick_nohz_idle_enter(void) { }
 static inline void tick_nohz_idle_exit(void) { }
 
@@ -136,6 +146,8 @@ static inline ktime_t tick_nohz_get_sleep_length(void)
 }
 static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; }
 static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
+
+static inline void tick_nohz_idle_stop_tick_protected(void) { }
 #endif /* !CONFIG_NO_HZ_COMMON */
 
 #ifdef CONFIG_NO_HZ_FULL
-- 
cgit v1.2.3


From 2aaf709a518d26563b80fd7a42379d7aa7ffed4a Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Thu, 15 Mar 2018 23:05:50 +0100
Subject: sched: idle: Do not stop the tick upfront in the idle loop

Push the decision whether or not to stop the tick somewhat deeper
into the idle loop.

Stopping the tick upfront leads to unpleasant outcomes in case the
idle governor doesn't agree with the nohz code on the duration of the
upcoming idle period.  Specifically, if the tick has been stopped and
the idle governor predicts short idle, the situation is bad regardless
of whether or not the prediction is accurate.  If it is accurate, the
tick has been stopped unnecessarily which means excessive overhead.
If it is not accurate, the CPU is likely to spend too much time in
the (shallow, because short idle has been predicted) idle state
selected by the governor [1].

As the first step towards addressing this problem, change the code
to make the tick stopping decision inside of the loop in do_idle().
In particular, do not stop the tick in the cpu_idle_poll() code path.
Also don't do that in tick_nohz_irq_exit() which doesn't really have
enough information on whether or not to stop the tick.

Link: https://marc.info/?l=linux-pm&m=150116085925208&w=2 # [1]
Link: https://tu-dresden.de/zih/forschung/ressourcen/dateien/projekte/haec/powernightmares.pdf
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/tick.h     |  2 ++
 kernel/sched/idle.c      |  9 ++++++---
 kernel/time/tick-sched.c | 26 ++++++++++++++++++--------
 3 files changed, 26 insertions(+), 11 deletions(-)

(limited to 'include/linux')

diff --git a/include/linux/tick.h b/include/linux/tick.h
index 1d253df9ea3c..fccebfba167e 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -116,6 +116,7 @@ extern bool tick_nohz_enabled;
 extern bool tick_nohz_tick_stopped(void);
 extern bool tick_nohz_tick_stopped_cpu(int cpu);
 extern void tick_nohz_idle_stop_tick(void);
+extern void tick_nohz_idle_restart_tick(void);
 extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);
 extern void tick_nohz_irq_exit(void);
@@ -137,6 +138,7 @@ static inline void tick_nohz_idle_stop_tick_protected(void)
 static inline int tick_nohz_tick_stopped(void) { return 0; }
 static inline int tick_nohz_tick_stopped_cpu(int cpu) { return 0; }
 static inline void tick_nohz_idle_stop_tick(void) { }
+static inline void tick_nohz_idle_restart_tick(void) { }
 static inline void tick_nohz_idle_enter(void) { }
 static inline void tick_nohz_idle_exit(void) { }
 
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index c0bc111878e6..3777e83c0b5a 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -216,13 +216,13 @@ static void do_idle(void)
 
 	__current_set_polling();
 	tick_nohz_idle_enter();
-	tick_nohz_idle_stop_tick_protected();
 
 	while (!need_resched()) {
 		check_pgt_cache();
 		rmb();
 
 		if (cpu_is_offline(cpu)) {
+			tick_nohz_idle_stop_tick_protected();
 			cpuhp_report_idle_dead();
 			arch_cpu_idle_dead();
 		}
@@ -236,10 +236,13 @@ static void do_idle(void)
 		 * broadcast device expired for us, we don't want to go deep
 		 * idle as we know that the IPI is going to arrive right away.
 		 */
-		if (cpu_idle_force_poll || tick_check_broadcast_expired())
+		if (cpu_idle_force_poll || tick_check_broadcast_expired()) {
+			tick_nohz_idle_restart_tick();
 			cpu_idle_poll();
-		else
+		} else {
+			tick_nohz_idle_stop_tick();
 			cpuidle_idle_call();
+		}
 		arch_cpu_idle_exit();
 	}
 
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 678349aec483..f5d37788ea85 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -960,12 +960,10 @@ void tick_nohz_irq_exit(void)
 {
 	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
 
-	if (ts->inidle) {
+	if (ts->inidle)
 		tick_nohz_start_idle(ts);
-		__tick_nohz_idle_stop_tick(ts);
-	} else {
+	else
 		tick_nohz_full_update_tick(ts);
-	}
 }
 
 /**
@@ -1026,6 +1024,20 @@ static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
 #endif
 }
 
+static void __tick_nohz_idle_restart_tick(struct tick_sched *ts, ktime_t now)
+{
+	tick_nohz_restart_sched_tick(ts, now);
+	tick_nohz_account_idle_ticks(ts);
+}
+
+void tick_nohz_idle_restart_tick(void)
+{
+	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
+
+	if (ts->tick_stopped)
+		__tick_nohz_idle_restart_tick(ts, ktime_get());
+}
+
 /**
  * tick_nohz_idle_exit - restart the idle tick from the idle task
  *
@@ -1050,10 +1062,8 @@ void tick_nohz_idle_exit(void)
 	if (ts->idle_active)
 		tick_nohz_stop_idle(ts, now);
 
-	if (ts->tick_stopped) {
-		tick_nohz_restart_sched_tick(ts, now);
-		tick_nohz_account_idle_ticks(ts);
-	}
+	if (ts->tick_stopped)
+		__tick_nohz_idle_restart_tick(ts, now);
 
 	local_irq_enable();
 }
-- 
cgit v1.2.3


From efefc97736e6f3261879bc9dddcb161224a455f5 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Tue, 20 Mar 2018 10:11:28 +0100
Subject: jiffies: Introduce USER_TICK_USEC and redefine TICK_USEC

Since the subsequent changes will need a TICK_USEC definition
analogous to TICK_NSEC, rename the existing TICK_USEC as
USER_TICK_USEC, update its users and redefine TICK_USEC
accordingly.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
---
 drivers/net/ethernet/sfc/mcdi.c | 2 +-
 include/linux/jiffies.h         | 7 +++++--
 kernel/time/ntp.c               | 2 +-
 3 files changed, 7 insertions(+), 4 deletions(-)

(limited to 'include/linux')

diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index 9c2567b0d93e..dfad93fca0a6 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -375,7 +375,7 @@ static int efx_mcdi_poll(struct efx_nic *efx)
 	 * because generally mcdi responses are fast. After that, back off
 	 * and poll once a jiffy (approximately)
 	 */
-	spins = TICK_USEC;
+	spins = USER_TICK_USEC;
 	finish = jiffies + MCDI_RPC_TIMEOUT;
 
 	while (1) {
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index 9385aa57497b..a27cf6652327 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -62,8 +62,11 @@ extern int register_refined_jiffies(long clock_tick_rate);
 /* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */
 #define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ)
 
-/* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
-#define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
+/* TICK_USEC is the time between ticks in usec assuming SHIFTED_HZ */
+#define TICK_USEC ((USEC_PER_SEC + HZ/2) / HZ)
+
+/* USER_TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
+#define USER_TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
 
 #ifndef __jiffy_arch_data
 #define __jiffy_arch_data
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 8d70da1b9a0d..a09ded765f6c 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -31,7 +31,7 @@
 
 
 /* USER_HZ period (usecs): */
-unsigned long			tick_usec = TICK_USEC;
+unsigned long			tick_usec = USER_TICK_USEC;
 
 /* SHIFTED_HZ period (nsecs): */
 unsigned long			tick_nsec;
-- 
cgit v1.2.3


From 45f1ff59e27ca59d33cc1a317e669d90022ccf7d Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Thu, 22 Mar 2018 17:50:49 +0100
Subject: cpuidle: Return nohz hint from cpuidle_select()

Add a new pointer argument to cpuidle_select() and to the ->select
cpuidle governor callback to allow a boolean value indicating
whether or not the tick should be stopped before entering the
selected state to be returned from there.

Make the ladder governor ignore that pointer (to preserve its
current behavior) and make the menu governor return 'false" through
it if:
 (1) the idle exit latency is constrained at 0, or
 (2) the selected state is a polling one, or
 (3) the expected idle period duration is within the tick period
     range.

In addition to that, the correction factor computations in the menu
governor need to take the possibility that the tick may not be
stopped into account to avoid artificially small correction factor
values.  To that end, add a mechanism to record tick wakeups, as
suggested by Peter Zijlstra, and use it to modify the menu_update()
behavior when tick wakeup occurs.  Namely, if the CPU is woken up by
the tick and the return value of tick_nohz_get_sleep_length() is not
within the tick boundary, the predicted idle duration is likely too
short, so make menu_update() try to compensate for that by updating
the governor statistics as though the CPU was idle for a long time.

Since the value returned through the new argument pointer of
cpuidle_select() is not used by its caller yet, this change by
itself is not expected to alter the functionality of the code.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 drivers/cpuidle/cpuidle.c          | 10 +++++--
 drivers/cpuidle/governors/ladder.c |  3 +-
 drivers/cpuidle/governors/menu.c   | 59 ++++++++++++++++++++++++++++++--------
 include/linux/cpuidle.h            |  8 ++++--
 include/linux/tick.h               |  2 ++
 kernel/sched/idle.c                |  4 ++-
 kernel/time/tick-sched.c           | 20 +++++++++++++
 7 files changed, 87 insertions(+), 19 deletions(-)

(limited to 'include/linux')

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 0003e9a02637..6df894d65d9e 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -272,12 +272,18 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
  *
  * @drv: the cpuidle driver
  * @dev: the cpuidle device
+ * @stop_tick: indication on whether or not to stop the tick
  *
  * Returns the index of the idle state.  The return value must not be negative.
+ *
+ * The memory location pointed to by @stop_tick is expected to be written the
+ * 'false' boolean value if the scheduler tick should not be stopped before
+ * entering the returned state.
  */
-int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
+int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
+		   bool *stop_tick)
 {
-	return cpuidle_curr_governor->select(drv, dev);
+	return cpuidle_curr_governor->select(drv, dev, stop_tick);
 }
 
 /**
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index 1ad8745fd6d6..b24883f85c99 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -63,9 +63,10 @@ static inline void ladder_do_selection(struct ladder_device *ldev,
  * ladder_select_state - selects the next state to enter
  * @drv: cpuidle driver
  * @dev: the CPU
+ * @dummy: not used
  */
 static int ladder_select_state(struct cpuidle_driver *drv,
-				struct cpuidle_device *dev)
+			       struct cpuidle_device *dev, bool *dummy)
 {
 	struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
 	struct device *device = get_cpu_device(dev->cpu);
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index aa390404e85f..f53a929bd2bd 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -123,6 +123,7 @@
 struct menu_device {
 	int		last_state_idx;
 	int             needs_update;
+	int             tick_wakeup;
 
 	unsigned int	next_timer_us;
 	unsigned int	predicted_us;
@@ -279,8 +280,10 @@ again:
  * menu_select - selects the next idle state to enter
  * @drv: cpuidle driver containing state data
  * @dev: the CPU
+ * @stop_tick: indication on whether or not to stop the tick
  */
-static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
+static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
+		       bool *stop_tick)
 {
 	struct menu_device *data = this_cpu_ptr(&menu_devices);
 	struct device *device = get_cpu_device(dev->cpu);
@@ -303,8 +306,10 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 		latency_req = resume_latency;
 
 	/* Special case when user has set very strict latency requirement */
-	if (unlikely(latency_req == 0))
+	if (unlikely(latency_req == 0)) {
+		*stop_tick = false;
 		return 0;
+	}
 
 	/* determine the expected residency time, round up */
 	data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length());
@@ -354,6 +359,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 	if (latency_req > interactivity_req)
 		latency_req = interactivity_req;
 
+	expected_interval = data->predicted_us;
 	/*
 	 * Find the idle state with the lowest power while satisfying
 	 * our constraints.
@@ -369,15 +375,30 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 			idx = i; /* first enabled state */
 		if (s->target_residency > data->predicted_us)
 			break;
-		if (s->exit_latency > latency_req)
+		if (s->exit_latency > latency_req) {
+			/*
+			 * If we break out of the loop for latency reasons, use
+			 * the target residency of the selected state as the
+			 * expected idle duration so that the tick is retained
+			 * as long as that target residency is low enough.
+			 */
+			expected_interval = drv->states[idx].target_residency;
 			break;
-
+		}
 		idx = i;
 	}
 
 	if (idx == -1)
 		idx = 0; /* No states enabled. Must use 0. */
 
+	/*
+	 * Don't stop the tick if the selected state is a polling one or if the
+	 * expected idle duration is shorter than the tick period length.
+	 */
+	if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) ||
+	    expected_interval < TICK_USEC)
+		*stop_tick = false;
+
 	data->last_state_idx = idx;
 
 	return data->last_state_idx;
@@ -397,6 +418,7 @@ static void menu_reflect(struct cpuidle_device *dev, int index)
 
 	data->last_state_idx = index;
 	data->needs_update = 1;
+	data->tick_wakeup = tick_nohz_idle_got_tick();
 }
 
 /**
@@ -427,14 +449,27 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 	 * assume the state was never reached and the exit latency is 0.
 	 */
 
-	/* measured value */
-	measured_us = cpuidle_get_last_residency(dev);
-
-	/* Deduct exit latency */
-	if (measured_us > 2 * target->exit_latency)
-		measured_us -= target->exit_latency;
-	else
-		measured_us /= 2;
+	if (data->tick_wakeup && data->next_timer_us > TICK_USEC) {
+		/*
+		 * The nohz code said that there wouldn't be any events within
+		 * the tick boundary (if the tick was stopped), but the idle
+		 * duration predictor had a differing opinion.  Since the CPU
+		 * was woken up by a tick (that wasn't stopped after all), the
+		 * predictor was not quite right, so assume that the CPU could
+		 * have been idle long (but not forever) to help the idle
+		 * duration predictor do a better job next time.
+		 */
+		measured_us = 9 * MAX_INTERESTING / 10;
+	} else {
+		/* measured value */
+		measured_us = cpuidle_get_last_residency(dev);
+
+		/* Deduct exit latency */
+		if (measured_us > 2 * target->exit_latency)
+			measured_us -= target->exit_latency;
+		else
+			measured_us /= 2;
+	}
 
 	/* Make sure our coefficients do not exceed unity */
 	if (measured_us > data->next_timer_us)
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index a806e94c482f..1eefabf1621f 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -135,7 +135,8 @@ extern bool cpuidle_not_available(struct cpuidle_driver *drv,
 				  struct cpuidle_device *dev);
 
 extern int cpuidle_select(struct cpuidle_driver *drv,
-			  struct cpuidle_device *dev);
+			  struct cpuidle_device *dev,
+			  bool *stop_tick);
 extern int cpuidle_enter(struct cpuidle_driver *drv,
 			 struct cpuidle_device *dev, int index);
 extern void cpuidle_reflect(struct cpuidle_device *dev, int index);
@@ -167,7 +168,7 @@ static inline bool cpuidle_not_available(struct cpuidle_driver *drv,
 					 struct cpuidle_device *dev)
 {return true; }
 static inline int cpuidle_select(struct cpuidle_driver *drv,
-				 struct cpuidle_device *dev)
+				 struct cpuidle_device *dev, bool *stop_tick)
 {return -ENODEV; }
 static inline int cpuidle_enter(struct cpuidle_driver *drv,
 				struct cpuidle_device *dev, int index)
@@ -250,7 +251,8 @@ struct cpuidle_governor {
 					struct cpuidle_device *dev);
 
 	int  (*select)		(struct cpuidle_driver *drv,
-					struct cpuidle_device *dev);
+					struct cpuidle_device *dev,
+					bool *stop_tick);
 	void (*reflect)		(struct cpuidle_device *dev, int index);
 };
 
diff --git a/include/linux/tick.h b/include/linux/tick.h
index fccebfba167e..ef0717e5e526 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -120,6 +120,7 @@ extern void tick_nohz_idle_restart_tick(void);
 extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);
 extern void tick_nohz_irq_exit(void);
+extern bool tick_nohz_idle_got_tick(void);
 extern ktime_t tick_nohz_get_sleep_length(void);
 extern unsigned long tick_nohz_get_idle_calls(void);
 extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu);
@@ -141,6 +142,7 @@ static inline void tick_nohz_idle_stop_tick(void) { }
 static inline void tick_nohz_idle_restart_tick(void) { }
 static inline void tick_nohz_idle_enter(void) { }
 static inline void tick_nohz_idle_exit(void) { }
+static inline bool tick_nohz_idle_got_tick(void) { return false; }
 
 static inline ktime_t tick_nohz_get_sleep_length(void)
 {
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 4f64835d38a8..a966bd2a6fa0 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -183,13 +183,15 @@ static void cpuidle_idle_call(void)
 		next_state = cpuidle_find_deepest_state(drv, dev);
 		call_cpuidle(drv, dev, next_state);
 	} else {
+		bool stop_tick = true;
+
 		tick_nohz_idle_stop_tick();
 		rcu_idle_enter();
 
 		/*
 		 * Ask the cpuidle framework to choose a convenient idle state.
 		 */
-		next_state = cpuidle_select(drv, dev);
+		next_state = cpuidle_select(drv, dev, &stop_tick);
 		entered_state = call_cpuidle(drv, dev, next_state);
 		/*
 		 * Give the governor an opportunity to reflect on the outcome
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index f5d37788ea85..69fe113cfc7f 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -966,6 +966,20 @@ void tick_nohz_irq_exit(void)
 		tick_nohz_full_update_tick(ts);
 }
 
+/**
+ * tick_nohz_idle_got_tick - Check whether or not the tick handler has run
+ */
+bool tick_nohz_idle_got_tick(void)
+{
+	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
+
+	if (ts->inidle > 1) {
+		ts->inidle = 1;
+		return true;
+	}
+	return false;
+}
+
 /**
  * tick_nohz_get_sleep_length - return the length of the current sleep
  *
@@ -1077,6 +1091,9 @@ static void tick_nohz_handler(struct clock_event_device *dev)
 	struct pt_regs *regs = get_irq_regs();
 	ktime_t now = ktime_get();
 
+	if (ts->inidle)
+		ts->inidle = 2;
+
 	dev->next_event = KTIME_MAX;
 
 	tick_sched_do_timer(now);
@@ -1174,6 +1191,9 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
 	struct pt_regs *regs = get_irq_regs();
 	ktime_t now = ktime_get();
 
+	if (ts->inidle)
+		ts->inidle = 2;
+
 	tick_sched_do_timer(now);
 
 	/*
-- 
cgit v1.2.3


From a59855cd8c613ba4bb95147f6176360d95f75e60 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Tue, 3 Apr 2018 23:17:00 +0200
Subject: time: hrtimer: Introduce hrtimer_next_event_without()

The next set of changes will need to compute the time to the next
hrtimer event over all hrtimers except for the scheduler tick one.

To that end introduce a new helper function,
hrtimer_next_event_without(), for computing the time until the next
hrtimer event over all timers except for one and modify the underlying
code in __hrtimer_next_event_base() to prepare it for being called by
that new function.

No intentional changes in functionality.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/hrtimer.h |  1 +
 kernel/time/hrtimer.c   | 55 +++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 54 insertions(+), 2 deletions(-)

(limited to 'include/linux')

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index c7902ca7c9f4..3892e9c8b2de 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -426,6 +426,7 @@ static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
 }
 
 extern u64 hrtimer_get_next_event(void);
+extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
 
 extern bool hrtimer_active(const struct hrtimer *timer);
 
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 23788100e214..6d387dbd7304 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -490,6 +490,7 @@ __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
 	while ((base = __next_base((cpu_base), &(active))))
 
 static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
+					 const struct hrtimer *exclude,
 					 unsigned int active,
 					 ktime_t expires_next)
 {
@@ -502,9 +503,24 @@ static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
 
 		next = timerqueue_getnext(&base->active);
 		timer = container_of(next, struct hrtimer, node);
+		if (timer == exclude) {
+			/* Get to the next timer in the queue. */
+			struct rb_node *rbn = rb_next(&next->node);
+
+			next = rb_entry_safe(rbn, struct timerqueue_node, node);
+			if (!next)
+				continue;
+
+			timer = container_of(next, struct hrtimer, node);
+		}
 		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 		if (expires < expires_next) {
 			expires_next = expires;
+
+			/* Skip cpu_base update if a timer is being excluded. */
+			if (exclude)
+				continue;
+
 			if (timer->is_soft)
 				cpu_base->softirq_next_timer = timer;
 			else
@@ -548,7 +564,8 @@ __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_
 	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
 		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
 		cpu_base->softirq_next_timer = NULL;
-		expires_next = __hrtimer_next_event_base(cpu_base, active, KTIME_MAX);
+		expires_next = __hrtimer_next_event_base(cpu_base, NULL,
+							 active, KTIME_MAX);
 
 		next_timer = cpu_base->softirq_next_timer;
 	}
@@ -556,7 +573,8 @@ __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_
 	if (active_mask & HRTIMER_ACTIVE_HARD) {
 		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
 		cpu_base->next_timer = next_timer;
-		expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next);
+		expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
+							 expires_next);
 	}
 
 	return expires_next;
@@ -1202,6 +1220,39 @@ u64 hrtimer_get_next_event(void)
 
 	return expires;
 }
+
+/**
+ * hrtimer_next_event_without - time until next expiry event w/o one timer
+ * @exclude:	timer to exclude
+ *
+ * Returns the next expiry time over all timers except for the @exclude one or
+ * KTIME_MAX if none of them is pending.
+ */
+u64 hrtimer_next_event_without(const struct hrtimer *exclude)
+{
+	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+	u64 expires = KTIME_MAX;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&cpu_base->lock, flags);
+
+	if (__hrtimer_hres_active(cpu_base)) {
+		unsigned int active;
+
+		if (!cpu_base->softirq_activated) {
+			active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
+			expires = __hrtimer_next_event_base(cpu_base, exclude,
+							    active, KTIME_MAX);
+		}
+		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
+		expires = __hrtimer_next_event_base(cpu_base, exclude, active,
+						    expires);
+	}
+
+	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+
+	return expires;
+}
 #endif
 
 static inline int hrtimer_clockid_to_base(clockid_t clock_id)
-- 
cgit v1.2.3


From 554c8aa8ecade210d58a252173bb8f2106552a44 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Tue, 3 Apr 2018 23:17:11 +0200
Subject: sched: idle: Select idle state before stopping the tick

In order to address the issue with short idle duration predictions
by the idle governor after the scheduler tick has been stopped,
reorder the code in cpuidle_idle_call() so that the governor idle
state selection runs before tick_nohz_idle_go_idle() and use the
"nohz" hint returned by cpuidle_select() to decide whether or not
to stop the tick.

This isn't straightforward, because menu_select() invokes
tick_nohz_get_sleep_length() to get the time to the next timer
event and the number returned by the latter comes from
__tick_nohz_idle_stop_tick().  Fortunately, however, it is possible
to compute that number without actually stopping the tick and with
the help of the existing code.

Namely, tick_nohz_get_sleep_length() can be made call
tick_nohz_next_event(), introduced earlier, to get the time to the
next non-highres timer event.  If that happens, tick_nohz_next_event()
need not be called by __tick_nohz_idle_stop_tick() again.

If it turns out that the scheduler tick cannot be stopped going
forward or the next timer event is too close for the tick to be
stopped, tick_nohz_get_sleep_length() can simply return the time to
the next event currently programmed into the corresponding clock
event device.

In addition to knowing the return value of tick_nohz_next_event(),
however, tick_nohz_get_sleep_length() needs to know the time to the
next highres timer event, but with the scheduler tick timer excluded,
which can be computed with the help of hrtimer_get_next_event().

That minimum of that number and the tick_nohz_next_event() return
value is the total time to the next timer event with the assumption
that the tick will be stopped.  It can be returned to the idle
governor which can use it for predicting idle duration (under the
assumption that the tick will be stopped) and deciding whether or
not it makes sense to stop the tick before putting the CPU into the
selected idle state.

With the above, the sleep_length field in struct tick_sched is not
necessary any more, so drop it.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199227
Reported-by: Doug Smythies <dsmythies@telus.net>
Reported-by: Thomas Ilsche <thomas.ilsche@tu-dresden.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/tick.h     |  2 ++
 kernel/sched/idle.c      | 11 ++++++---
 kernel/time/tick-sched.c | 61 ++++++++++++++++++++++++++++++++++++++----------
 kernel/time/tick-sched.h |  2 --
 4 files changed, 59 insertions(+), 17 deletions(-)

(limited to 'include/linux')

diff --git a/include/linux/tick.h b/include/linux/tick.h
index ef0717e5e526..e8e7ff16b929 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -116,6 +116,7 @@ extern bool tick_nohz_enabled;
 extern bool tick_nohz_tick_stopped(void);
 extern bool tick_nohz_tick_stopped_cpu(int cpu);
 extern void tick_nohz_idle_stop_tick(void);
+extern void tick_nohz_idle_retain_tick(void);
 extern void tick_nohz_idle_restart_tick(void);
 extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);
@@ -139,6 +140,7 @@ static inline void tick_nohz_idle_stop_tick_protected(void)
 static inline int tick_nohz_tick_stopped(void) { return 0; }
 static inline int tick_nohz_tick_stopped_cpu(int cpu) { return 0; }
 static inline void tick_nohz_idle_stop_tick(void) { }
+static inline void tick_nohz_idle_retain_tick(void) { }
 static inline void tick_nohz_idle_restart_tick(void) { }
 static inline void tick_nohz_idle_enter(void) { }
 static inline void tick_nohz_idle_exit(void) { }
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index a966bd2a6fa0..1a3e9bddd17b 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -185,13 +185,18 @@ static void cpuidle_idle_call(void)
 	} else {
 		bool stop_tick = true;
 
-		tick_nohz_idle_stop_tick();
-		rcu_idle_enter();
-
 		/*
 		 * Ask the cpuidle framework to choose a convenient idle state.
 		 */
 		next_state = cpuidle_select(drv, dev, &stop_tick);
+
+		if (stop_tick)
+			tick_nohz_idle_stop_tick();
+		else
+			tick_nohz_idle_retain_tick();
+
+		rcu_idle_enter();
+
 		entered_state = call_cpuidle(drv, dev, next_state);
 		/*
 		 * Give the governor an opportunity to reflect on the outcome
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index f56d2c695712..c57c98c7e953 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -913,16 +913,19 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
 
 static void __tick_nohz_idle_stop_tick(struct tick_sched *ts)
 {
-	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
 	ktime_t expires;
 	int cpu = smp_processor_id();
 
-	WARN_ON_ONCE(ts->timer_expires_base);
-
-	if (!can_stop_idle_tick(cpu, ts))
-		goto out;
-
-	expires = tick_nohz_next_event(ts, cpu);
+	/*
+	 * If tick_nohz_get_sleep_length() ran tick_nohz_next_event(), the
+	 * tick timer expiration time is known already.
+	 */
+	if (ts->timer_expires_base)
+		expires = ts->timer_expires;
+	else if (can_stop_idle_tick(cpu, ts))
+		expires = tick_nohz_next_event(ts, cpu);
+	else
+		return;
 
 	ts->idle_calls++;
 
@@ -941,9 +944,6 @@ static void __tick_nohz_idle_stop_tick(struct tick_sched *ts)
 	} else {
 		tick_nohz_retain_tick(ts);
 	}
-
-out:
-	ts->sleep_length = ktime_sub(dev->next_event, ts->idle_entrytime);
 }
 
 /**
@@ -956,6 +956,16 @@ void tick_nohz_idle_stop_tick(void)
 	__tick_nohz_idle_stop_tick(this_cpu_ptr(&tick_cpu_sched));
 }
 
+void tick_nohz_idle_retain_tick(void)
+{
+	tick_nohz_retain_tick(this_cpu_ptr(&tick_cpu_sched));
+	/*
+	 * Undo the effect of get_next_timer_interrupt() called from
+	 * tick_nohz_next_event().
+	 */
+	timer_clear_idle();
+}
+
 /**
  * tick_nohz_idle_enter - prepare for entering idle on the current CPU
  *
@@ -1012,15 +1022,42 @@ bool tick_nohz_idle_got_tick(void)
 }
 
 /**
- * tick_nohz_get_sleep_length - return the length of the current sleep
+ * tick_nohz_get_sleep_length - return the expected length of the current sleep
  *
  * Called from power state control code with interrupts disabled
  */
 ktime_t tick_nohz_get_sleep_length(void)
 {
+	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
 	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
+	int cpu = smp_processor_id();
+	/*
+	 * The idle entry time is expected to be a sufficient approximation of
+	 * the current time at this point.
+	 */
+	ktime_t now = ts->idle_entrytime;
+	ktime_t next_event;
+
+	WARN_ON_ONCE(!ts->inidle);
+
+	if (!can_stop_idle_tick(cpu, ts))
+		goto out_dev;
+
+	next_event = tick_nohz_next_event(ts, cpu);
+	if (!next_event)
+		goto out_dev;
+
+	/*
+	 * If the next highres timer to expire is earlier than next_event, the
+	 * idle governor needs to know that.
+	 */
+	next_event = min_t(u64, next_event,
+			   hrtimer_next_event_without(&ts->sched_timer));
+
+	return ktime_sub(next_event, now);
 
-	return ts->sleep_length;
+out_dev:
+	return ktime_sub(dev->next_event, now);
 }
 
 /**
diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h
index 53e45a39bdbc..2b845f2c44b1 100644
--- a/kernel/time/tick-sched.h
+++ b/kernel/time/tick-sched.h
@@ -38,7 +38,6 @@ enum tick_nohz_mode {
  * @idle_exittime:	Time when the idle state was left
  * @idle_sleeptime:	Sum of the time slept in idle with sched tick stopped
  * @iowait_sleeptime:	Sum of the time slept in idle with sched tick stopped, with IO outstanding
- * @sleep_length:	Duration of the current idle sleep
  * @timer_expires:	Anticipated timer expiration time (in case sched tick is stopped)
  * @timer_expires_base:	Base time clock monotonic for @timer_expires
  * @do_timer_lst:	CPU was the last one doing do_timer before going idle
@@ -60,7 +59,6 @@ struct tick_sched {
 	ktime_t				idle_exittime;
 	ktime_t				idle_sleeptime;
 	ktime_t				iowait_sleeptime;
-	ktime_t				sleep_length;
 	unsigned long			last_jiffies;
 	u64				timer_expires;
 	u64				timer_expires_base;
-- 
cgit v1.2.3


From 296bb1e51a4838a6488ec5ce676607093482ecbc Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Thu, 5 Apr 2018 19:12:34 +0200
Subject: cpuidle: menu: Refine idle state selection for running tick

If the tick isn't stopped, the target residency of the state selected
by the menu governor may be greater than the actual time to the next
tick and that means lost energy.

To avoid that, make tick_nohz_get_sleep_length() return the current
time to the next event (before stopping the tick) in addition to the
estimated one via an extra pointer argument and make menu_select()
use that value to refine the state selection when necessary.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 drivers/cpuidle/governors/menu.c | 27 +++++++++++++++++++++++++--
 include/linux/tick.h             |  7 ++++---
 kernel/time/tick-sched.c         | 12 ++++++------
 3 files changed, 35 insertions(+), 11 deletions(-)

(limited to 'include/linux')

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index f53a929bd2bd..267982e471e0 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -295,6 +295,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 	unsigned int expected_interval;
 	unsigned long nr_iowaiters, cpu_load;
 	int resume_latency = dev_pm_qos_raw_read_value(device);
+	ktime_t delta_next;
 
 	if (data->needs_update) {
 		menu_update(drv, dev);
@@ -312,7 +313,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 	}
 
 	/* determine the expected residency time, round up */
-	data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length());
+	data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length(&delta_next));
 
 	get_iowait_load(&nr_iowaiters, &cpu_load);
 	data->bucket = which_bucket(data->next_timer_us, nr_iowaiters);
@@ -396,9 +397,31 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 	 * expected idle duration is shorter than the tick period length.
 	 */
 	if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) ||
-	    expected_interval < TICK_USEC)
+	    expected_interval < TICK_USEC) {
+		unsigned int delta_next_us = ktime_to_us(delta_next);
+
 		*stop_tick = false;
 
+		if (!tick_nohz_tick_stopped() && idx > 0 &&
+		    drv->states[idx].target_residency > delta_next_us) {
+			/*
+			 * The tick is not going to be stopped and the target
+			 * residency of the state to be returned is not within
+			 * the time until the next timer event including the
+			 * tick, so try to correct that.
+			 */
+			for (i = idx - 1; i >= 0; i--) {
+			    if (drv->states[i].disabled ||
+			        dev->states_usage[i].disable)
+					continue;
+
+				idx = i;
+				if (drv->states[i].target_residency <= delta_next_us)
+					break;
+			}
+		}
+	}
+
 	data->last_state_idx = idx;
 
 	return data->last_state_idx;
diff --git a/include/linux/tick.h b/include/linux/tick.h
index e8e7ff16b929..55388ab45fd4 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -122,7 +122,7 @@ extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);
 extern void tick_nohz_irq_exit(void);
 extern bool tick_nohz_idle_got_tick(void);
-extern ktime_t tick_nohz_get_sleep_length(void);
+extern ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next);
 extern unsigned long tick_nohz_get_idle_calls(void);
 extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu);
 extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
@@ -146,9 +146,10 @@ static inline void tick_nohz_idle_enter(void) { }
 static inline void tick_nohz_idle_exit(void) { }
 static inline bool tick_nohz_idle_got_tick(void) { return false; }
 
-static inline ktime_t tick_nohz_get_sleep_length(void)
+static inline ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next)
 {
-	return NSEC_PER_SEC / HZ;
+	*delta_next = TICK_NSEC;
+	return *delta_next;
 }
 static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; }
 static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index c57c98c7e953..edb9d49b4996 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1023,10 +1023,11 @@ bool tick_nohz_idle_got_tick(void)
 
 /**
  * tick_nohz_get_sleep_length - return the expected length of the current sleep
+ * @delta_next: duration until the next event if the tick cannot be stopped
  *
  * Called from power state control code with interrupts disabled
  */
-ktime_t tick_nohz_get_sleep_length(void)
+ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next)
 {
 	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
 	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
@@ -1040,12 +1041,14 @@ ktime_t tick_nohz_get_sleep_length(void)
 
 	WARN_ON_ONCE(!ts->inidle);
 
+	*delta_next = ktime_sub(dev->next_event, now);
+
 	if (!can_stop_idle_tick(cpu, ts))
-		goto out_dev;
+		return *delta_next;
 
 	next_event = tick_nohz_next_event(ts, cpu);
 	if (!next_event)
-		goto out_dev;
+		return *delta_next;
 
 	/*
 	 * If the next highres timer to expire is earlier than next_event, the
@@ -1055,9 +1058,6 @@ ktime_t tick_nohz_get_sleep_length(void)
 			   hrtimer_next_event_without(&ts->sched_timer));
 
 	return ktime_sub(next_event, now);
-
-out_dev:
-	return ktime_sub(dev->next_event, now);
 }
 
 /**
-- 
cgit v1.2.3


From 2dd0df8472ff9bb520673cb5862b08be9290c9fa Mon Sep 17 00:00:00 2001
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: Tue, 3 Apr 2018 15:37:39 +0530
Subject: cpufreq: Drop cpufreq_table_validate_and_show()

This isn't used anymore. Remove the helper and update documentation
accordingly.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 Documentation/cpu-freq/core.txt        | 12 +++++-------
 Documentation/cpu-freq/cpu-drivers.txt |  6 ++----
 drivers/cpufreq/freq_table.c           | 14 --------------
 include/linux/cpufreq.h                |  2 --
 4 files changed, 7 insertions(+), 27 deletions(-)

(limited to 'include/linux')

diff --git a/Documentation/cpu-freq/core.txt b/Documentation/cpu-freq/core.txt
index 978463a7c81e..073f128af5a7 100644
--- a/Documentation/cpu-freq/core.txt
+++ b/Documentation/cpu-freq/core.txt
@@ -97,12 +97,10 @@ flags	- flags of the cpufreq driver
 ==================================================================
 For details about OPP, see Documentation/power/opp.txt
 
-dev_pm_opp_init_cpufreq_table - cpufreq framework typically is initialized with
-	cpufreq_table_validate_and_show() which is provided with the list of
-	frequencies that are available for operation. This function provides
-	a ready to use conversion routine to translate the OPP layer's internal
-	information about the available frequencies into a format readily
-	providable to cpufreq.
+dev_pm_opp_init_cpufreq_table -
+	This function provides a ready to use conversion routine to translate
+	the OPP layer's internal information about the available frequencies
+	into a format readily providable to cpufreq.
 
 	WARNING: Do not use this function in interrupt context.
 
@@ -112,7 +110,7 @@ dev_pm_opp_init_cpufreq_table - cpufreq framework typically is initialized with
 		/* Do things */
 		r = dev_pm_opp_init_cpufreq_table(dev, &freq_table);
 		if (!r)
-			cpufreq_table_validate_and_show(policy, freq_table);
+			policy->freq_table = freq_table;
 		/* Do other things */
 	 }
 
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index 61546ac578d6..6e353d00cdc6 100644
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -259,10 +259,8 @@ CPUFREQ_ENTRY_INVALID. The entries don't need to be in sorted in any
 particular order, but if they are cpufreq core will do DVFS a bit
 quickly for them as search for best match is faster.
 
-By calling cpufreq_table_validate_and_show(), the cpuinfo.min_freq and
-cpuinfo.max_freq values are detected, and policy->min and policy->max
-are set to the same values. This is helpful for the per-CPU
-initialization stage.
+The cpufreq table is verified automatically by the core if the policy contains a
+valid pointer in its policy->freq_table field.
 
 cpufreq_frequency_table_verify() assures that at least one valid
 frequency is within policy->min and policy->max, and all other criteria
diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index 10e119ae66dd..3a8cc99e6815 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c
@@ -352,20 +352,6 @@ static int set_freq_table_sorted(struct cpufreq_policy *policy)
 	return 0;
 }
 
-int cpufreq_table_validate_and_show(struct cpufreq_policy *policy,
-				      struct cpufreq_frequency_table *table)
-{
-	int ret;
-
-	ret = cpufreq_frequency_table_cpuinfo(policy, table);
-	if (ret)
-		return ret;
-
-	policy->freq_table = table;
-	return 0;
-}
-EXPORT_SYMBOL_GPL(cpufreq_table_validate_and_show);
-
 int cpufreq_table_validate_and_sort(struct cpufreq_policy *policy)
 {
 	int ret;
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 1fe49724da9e..87f48dd932eb 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -960,8 +960,6 @@ extern void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
 extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs;
 extern struct freq_attr cpufreq_freq_attr_scaling_boost_freqs;
 extern struct freq_attr *cpufreq_generic_attr[];
-int cpufreq_table_validate_and_show(struct cpufreq_policy *policy,
-				      struct cpufreq_frequency_table *table);
 int cpufreq_table_validate_and_sort(struct cpufreq_policy *policy);
 
 unsigned int cpufreq_generic_get(unsigned int cpu);
-- 
cgit v1.2.3