Message-Id: <1475652794-4486-2-git-send-email-daniel.lezcano@linaro.org>
Date:   Wed,  5 Oct 2016 09:33:13 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     rjw@...ysocki.net
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: [PATCH 2/2] cpuidle: governors: Move the files to the upper directory

Currently the different governors are stored in the subdir
'governors'. That is not a problem.

However, that forces to declare some private structure in the
include/linux/cpuidle.h header because these governor files
don't have access to the private 'cpuidle.h' located in
drivers/cpuidle.

Instead of having the governors in the separate directory, move
them along with the drivers and prefix them with 'governor-',
that allows to do a proper cleanup in the cpuidle headers.

Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
---
 drivers/cpuidle/Makefile           |   7 +-
 drivers/cpuidle/governor-ladder.c  | 197 +++++++++++++++
 drivers/cpuidle/governor-menu.c    | 496 +++++++++++++++++++++++++++++++++++++
 drivers/cpuidle/governors/Makefile |   6 -
 drivers/cpuidle/governors/ladder.c | 197 ---------------
 drivers/cpuidle/governors/menu.c   | 496 -------------------------------------
 6 files changed, 699 insertions(+), 700 deletions(-)
 create mode 100644 drivers/cpuidle/governor-ladder.c
 create mode 100644 drivers/cpuidle/governor-menu.c
 delete mode 100644 drivers/cpuidle/governors/Makefile
 delete mode 100644 drivers/cpuidle/governors/ladder.c
 delete mode 100644 drivers/cpuidle/governors/menu.c

diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 3ba81b1..b21ada9 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -2,7 +2,7 @@
 # Makefile for cpuidle.
 #
 
-obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
+obj-y += cpuidle.o driver.o governor.o sysfs.o
 obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
 obj-$(CONFIG_DT_IDLE_STATES)		  += dt_idle_states.o
 
@@ -27,3 +27,8 @@ obj-$(CONFIG_MIPS_CPS_CPUIDLE)		+= cpuidle-cps.o
 # POWERPC drivers
 obj-$(CONFIG_PSERIES_CPUIDLE)		+= cpuidle-pseries.o
 obj-$(CONFIG_POWERNV_CPUIDLE)		+= cpuidle-powernv.o
+
+###############################################################################
+# Governors
+obj-$(CONFIG_CPU_IDLE_GOV_LADDER) += governor-ladder.o
+obj-$(CONFIG_CPU_IDLE_GOV_MENU) += governor-menu.o
diff --git a/drivers/cpuidle/governor-ladder.c b/drivers/cpuidle/governor-ladder.c
new file mode 100644
index 0000000..fe8f089
--- /dev/null
+++ b/drivers/cpuidle/governor-ladder.c
@@ -0,0 +1,197 @@
+/*
+ * ladder.c - the residency ladder algorithm
+ *
+ *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@...el.com>
+ *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@...el.com>
+ *  Copyright (C) 2004, 2005 Dominik Brodowski <linux@...do.de>
+ *
+ * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
+ *               Shaohua Li <shaohua.li@...el.com>
+ *               Adam Belay <abelay@...ell.com>
+ *
+ * This code is licenced under the GPL.
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpuidle.h>
+#include <linux/pm_qos.h>
+#include <linux/jiffies.h>
+#include <linux/tick.h>
+
+#include <asm/io.h>
+#include <asm/uaccess.h>
+
+#define PROMOTION_COUNT 4
+#define DEMOTION_COUNT 1
+
+struct ladder_device_state {
+	struct {
+		u32 promotion_count;
+		u32 demotion_count;
+		u32 promotion_time;
+		u32 demotion_time;
+	} threshold;
+	struct {
+		int promotion_count;
+		int demotion_count;
+	} stats;
+};
+
+struct ladder_device {
+	struct ladder_device_state states[CPUIDLE_STATE_MAX];
+	int last_state_idx;
+};
+
+static DEFINE_PER_CPU(struct ladder_device, ladder_devices);
+
+/**
+ * ladder_do_selection - prepares private data for a state change
+ * @ldev: the ladder device
+ * @old_idx: the current state index
+ * @new_idx: the new target state index
+ */
+static inline void ladder_do_selection(struct ladder_device *ldev,
+				       int old_idx, int new_idx)
+{
+	ldev->states[old_idx].stats.promotion_count = 0;
+	ldev->states[old_idx].stats.demotion_count = 0;
+	ldev->last_state_idx = new_idx;
+}
+
+/**
+ * ladder_select_state - selects the next state to enter
+ * @drv: cpuidle driver
+ * @dev: the CPU
+ */
+static int ladder_select_state(struct cpuidle_driver *drv,
+				struct cpuidle_device *dev)
+{
+	struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
+	struct ladder_device_state *last_state;
+	int last_residency, last_idx = ldev->last_state_idx;
+	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
+
+	/* Special case when user has set very strict latency requirement */
+	if (unlikely(latency_req == 0)) {
+		ladder_do_selection(ldev, last_idx, 0);
+		return 0;
+	}
+
+	last_state = &ldev->states[last_idx];
+
+	last_residency = cpuidle_get_last_residency(dev) - drv->states[last_idx].exit_latency;
+
+	/* consider promotion */
+	if (last_idx < drv->state_count - 1 &&
+	    !drv->states[last_idx + 1].disabled &&
+	    !dev->states_usage[last_idx + 1].disable &&
+	    last_residency > last_state->threshold.promotion_time &&
+	    drv->states[last_idx + 1].exit_latency <= latency_req) {
+		last_state->stats.promotion_count++;
+		last_state->stats.demotion_count = 0;
+		if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) {
+			ladder_do_selection(ldev, last_idx, last_idx + 1);
+			return last_idx + 1;
+		}
+	}
+
+	/* consider demotion */
+	if (last_idx > CPUIDLE_DRIVER_STATE_START &&
+	    (drv->states[last_idx].disabled ||
+	    dev->states_usage[last_idx].disable ||
+	    drv->states[last_idx].exit_latency > latency_req)) {
+		int i;
+
+		for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) {
+			if (drv->states[i].exit_latency <= latency_req)
+				break;
+		}
+		ladder_do_selection(ldev, last_idx, i);
+		return i;
+	}
+
+	if (last_idx > CPUIDLE_DRIVER_STATE_START &&
+	    last_residency < last_state->threshold.demotion_time) {
+		last_state->stats.demotion_count++;
+		last_state->stats.promotion_count = 0;
+		if (last_state->stats.demotion_count >= last_state->threshold.demotion_count) {
+			ladder_do_selection(ldev, last_idx, last_idx - 1);
+			return last_idx - 1;
+		}
+	}
+
+	/* otherwise remain at the current state */
+	return last_idx;
+}
+
+/**
+ * ladder_enable_device - setup for the governor
+ * @drv: cpuidle driver
+ * @dev: the CPU
+ */
+static int ladder_enable_device(struct cpuidle_driver *drv,
+				struct cpuidle_device *dev)
+{
+	int i;
+	struct ladder_device *ldev = &per_cpu(ladder_devices, dev->cpu);
+	struct ladder_device_state *lstate;
+	struct cpuidle_state *state;
+
+	ldev->last_state_idx = CPUIDLE_DRIVER_STATE_START;
+
+	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
+		state = &drv->states[i];
+		lstate = &ldev->states[i];
+
+		lstate->stats.promotion_count = 0;
+		lstate->stats.demotion_count = 0;
+
+		lstate->threshold.promotion_count = PROMOTION_COUNT;
+		lstate->threshold.demotion_count = DEMOTION_COUNT;
+
+		if (i < drv->state_count - 1)
+			lstate->threshold.promotion_time = state->exit_latency;
+		if (i > CPUIDLE_DRIVER_STATE_START)
+			lstate->threshold.demotion_time = state->exit_latency;
+	}
+
+	return 0;
+}
+
+/**
+ * ladder_reflect - update the correct last_state_idx
+ * @dev: the CPU
+ * @index: the index of actual state entered
+ */
+static void ladder_reflect(struct cpuidle_device *dev, int index)
+{
+	struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
+	if (index > 0)
+		ldev->last_state_idx = index;
+}
+
+static struct cpuidle_governor ladder_governor = {
+	.name =		"ladder",
+	.rating =	10,
+	.enable =	ladder_enable_device,
+	.select =	ladder_select_state,
+	.reflect =	ladder_reflect,
+};
+
+/**
+ * init_ladder - initializes the governor
+ */
+static int __init init_ladder(void)
+{
+	/*
+	 * When NO_HZ is disabled, or when booting with nohz=off, the ladder
+	 * governor is better so give it a higher rating than the menu
+	 * governor.
+	 */
+	if (!tick_nohz_enabled)
+		ladder_governor.rating = 25;
+
+	return cpuidle_register_governor(&ladder_governor);
+}
+
+postcore_initcall(init_ladder);
diff --git a/drivers/cpuidle/governor-menu.c b/drivers/cpuidle/governor-menu.c
new file mode 100644
index 0000000..d9b5b93
--- /dev/null
+++ b/drivers/cpuidle/governor-menu.c
@@ -0,0 +1,496 @@
+/*
+ * menu.c - the menu idle governor
+ *
+ * Copyright (C) 2006-2007 Adam Belay <abelay@...ell.com>
+ * Copyright (C) 2009 Intel Corporation
+ * Author:
+ *        Arjan van de Ven <arjan@...ux.intel.com>
+ *
+ * This code is licenced under the GPL version 2 as described
+ * in the COPYING file that acompanies the Linux Kernel.
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpuidle.h>
+#include <linux/pm_qos.h>
+#include <linux/time.h>
+#include <linux/ktime.h>
+#include <linux/hrtimer.h>
+#include <linux/tick.h>
+#include <linux/sched.h>
+#include <linux/math64.h>
+
+/*
+ * Please note when changing the tuning values:
+ * If (MAX_INTERESTING-1) * RESOLUTION > UINT_MAX, the result of
+ * a scaling operation multiplication may overflow on 32 bit platforms.
+ * In that case, #define RESOLUTION as ULL to get 64 bit result:
+ * #define RESOLUTION 1024ULL
+ *
+ * The default values do not overflow.
+ */
+#define BUCKETS 12
+#define INTERVAL_SHIFT 3
+#define INTERVALS (1UL << INTERVAL_SHIFT)
+#define RESOLUTION 1024
+#define DECAY 8
+#define MAX_INTERESTING 50000
+
+
+/*
+ * Concepts and ideas behind the menu governor
+ *
+ * For the menu governor, there are 3 decision factors for picking a C
+ * state:
+ * 1) Energy break even point
+ * 2) Performance impact
+ * 3) Latency tolerance (from pmqos infrastructure)
+ * These these three factors are treated independently.
+ *
+ * Energy break even point
+ * -----------------------
+ * C state entry and exit have an energy cost, and a certain amount of time in
+ * the  C state is required to actually break even on this cost. CPUIDLE
+ * provides us this duration in the "target_residency" field. So all that we
+ * need is a good prediction of how long we'll be idle. Like the traditional
+ * menu governor, we start with the actual known "next timer event" time.
+ *
+ * Since there are other source of wakeups (interrupts for example) than
+ * the next timer event, this estimation is rather optimistic. To get a
+ * more realistic estimate, a correction factor is applied to the estimate,
+ * that is based on historic behavior. For example, if in the past the actual
+ * duration always was 50% of the next timer tick, the correction factor will
+ * be 0.5.
+ *
+ * menu uses a running average for this correction factor, however it uses a
+ * set of factors, not just a single factor. This stems from the realization
+ * that the ratio is dependent on the order of magnitude of the expected
+ * duration; if we expect 500 milliseconds of idle time the likelihood of
+ * getting an interrupt very early is much higher than if we expect 50 micro
+ * seconds of idle time. A second independent factor that has big impact on
+ * the actual factor is if there is (disk) IO outstanding or not.
+ * (as a special twist, we consider every sleep longer than 50 milliseconds
+ * as perfect; there are no power gains for sleeping longer than this)
+ *
+ * For these two reasons we keep an array of 12 independent factors, that gets
+ * indexed based on the magnitude of the expected duration as well as the
+ * "is IO outstanding" property.
+ *
+ * Repeatable-interval-detector
+ * ----------------------------
+ * There are some cases where "next timer" is a completely unusable predictor:
+ * Those cases where the interval is fixed, for example due to hardware
+ * interrupt mitigation, but also due to fixed transfer rate devices such as
+ * mice.
+ * For this, we use a different predictor: We track the duration of the last 8
+ * intervals and if the stand deviation of these 8 intervals is below a
+ * threshold value, we use the average of these intervals as prediction.
+ *
+ * Limiting Performance Impact
+ * ---------------------------
+ * C states, especially those with large exit latencies, can have a real
+ * noticeable impact on workloads, which is not acceptable for most sysadmins,
+ * and in addition, less performance has a power price of its own.
+ *
+ * As a general rule of thumb, menu assumes that the following heuristic
+ * holds:
+ *     The busier the system, the less impact of C states is acceptable
+ *
+ * This rule-of-thumb is implemented using a performance-multiplier:
+ * If the exit latency times the performance multiplier is longer than
+ * the predicted duration, the C state is not considered a candidate
+ * for selection due to a too high performance impact. So the higher
+ * this multiplier is, the longer we need to be idle to pick a deep C
+ * state, and thus the less likely a busy CPU will hit such a deep
+ * C state.
+ *
+ * Two factors are used in determing this multiplier:
+ * a value of 10 is added for each point of "per cpu load average" we have.
+ * a value of 5 points is added for each process that is waiting for
+ * IO on this CPU.
+ * (these values are experimentally determined)
+ *
+ * The load average factor gives a longer term (few seconds) input to the
+ * decision, while the iowait value gives a cpu local instantanious input.
+ * The iowait factor may look low, but realize that this is also already
+ * represented in the system load average.
+ *
+ */
+
+struct menu_device {
+	int		last_state_idx;
+	int             needs_update;
+
+	unsigned int	next_timer_us;
+	unsigned int	predicted_us;
+	unsigned int	bucket;
+	unsigned int	correction_factor[BUCKETS];
+	unsigned int	intervals[INTERVALS];
+	int		interval_ptr;
+};
+
+
+#define LOAD_INT(x) ((x) >> FSHIFT)
+#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
+
+static inline int get_loadavg(unsigned long load)
+{
+	return LOAD_INT(load) * 10 + LOAD_FRAC(load) / 10;
+}
+
+static inline int which_bucket(unsigned int duration, unsigned long nr_iowaiters)
+{
+	int bucket = 0;
+
+	/*
+	 * We keep two groups of stats; one with no
+	 * IO pending, one without.
+	 * This allows us to calculate
+	 * E(duration)|iowait
+	 */
+	if (nr_iowaiters)
+		bucket = BUCKETS/2;
+
+	if (duration < 10)
+		return bucket;
+	if (duration < 100)
+		return bucket + 1;
+	if (duration < 1000)
+		return bucket + 2;
+	if (duration < 10000)
+		return bucket + 3;
+	if (duration < 100000)
+		return bucket + 4;
+	return bucket + 5;
+}
+
+/*
+ * Return a multiplier for the exit latency that is intended
+ * to take performance requirements into account.
+ * The more performance critical we estimate the system
+ * to be, the higher this multiplier, and thus the higher
+ * the barrier to go to an expensive C state.
+ */
+static inline int performance_multiplier(unsigned long nr_iowaiters, unsigned long load)
+{
+	int mult = 1;
+
+	/* for higher loadavg, we are more reluctant */
+
+	mult += 2 * get_loadavg(load);
+
+	/* for IO wait tasks (per cpu!) we add 5x each */
+	mult += 10 * nr_iowaiters;
+
+	return mult;
+}
+
+static DEFINE_PER_CPU(struct menu_device, menu_devices);
+
+static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev);
+
+/*
+ * Try detecting repeating patterns by keeping track of the last 8
+ * intervals, and checking if the standard deviation of that set
+ * of points is below a threshold. If it is... then use the
+ * average of these 8 points as the estimated value.
+ */
+static unsigned int get_typical_interval(struct menu_device *data)
+{
+	int i, divisor;
+	unsigned int max, thresh, avg;
+	uint64_t sum, variance;
+
+	thresh = UINT_MAX; /* Discard outliers above this value */
+
+again:
+
+	/* First calculate the average of past intervals */
+	max = 0;
+	sum = 0;
+	divisor = 0;
+	for (i = 0; i < INTERVALS; i++) {
+		unsigned int value = data->intervals[i];
+		if (value <= thresh) {
+			sum += value;
+			divisor++;
+			if (value > max)
+				max = value;
+		}
+	}
+	if (divisor == INTERVALS)
+		avg = sum >> INTERVAL_SHIFT;
+	else
+		avg = div_u64(sum, divisor);
+
+	/* Then try to determine variance */
+	variance = 0;
+	for (i = 0; i < INTERVALS; i++) {
+		unsigned int value = data->intervals[i];
+		if (value <= thresh) {
+			int64_t diff = (int64_t)value - avg;
+			variance += diff * diff;
+		}
+	}
+	if (divisor == INTERVALS)
+		variance >>= INTERVAL_SHIFT;
+	else
+		do_div(variance, divisor);
+
+	/*
+	 * The typical interval is obtained when standard deviation is
+	 * small (stddev <= 20 us, variance <= 400 us^2) or standard
+	 * deviation is small compared to the average interval (avg >
+	 * 6*stddev, avg^2 > 36*variance). The average is smaller than
+	 * UINT_MAX aka U32_MAX, so computing its square does not
+	 * overflow a u64. We simply reject this candidate average if
+	 * the standard deviation is greater than 715 s (which is
+	 * rather unlikely).
+	 *
+	 * Use this result only if there is no timer to wake us up sooner.
+	 */
+	if (likely(variance <= U64_MAX/36)) {
+		if ((((u64)avg*avg > variance*36) && (divisor * 4 >= INTERVALS * 3))
+							|| variance <= 400) {
+			return avg;
+		}
+	}
+
+	/*
+	 * If we have outliers to the upside in our distribution, discard
+	 * those by setting the threshold to exclude these outliers, then
+	 * calculate the average and standard deviation again. Once we get
+	 * down to the bottom 3/4 of our samples, stop excluding samples.
+	 *
+	 * This can deal with workloads that have long pauses interspersed
+	 * with sporadic activity with a bunch of short pauses.
+	 */
+	if ((divisor * 4) <= INTERVALS * 3)
+		return UINT_MAX;
+
+	thresh = max - 1;
+	goto again;
+}
+
+/**
+ * menu_select - selects the next idle state to enter
+ * @drv: cpuidle driver containing state data
+ * @dev: the CPU
+ */
+static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
+{
+	struct menu_device *data = this_cpu_ptr(&menu_devices);
+	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
+	int i;
+	unsigned int interactivity_req;
+	unsigned int expected_interval;
+	unsigned long nr_iowaiters, cpu_load;
+
+	if (data->needs_update) {
+		menu_update(drv, dev);
+		data->needs_update = 0;
+	}
+
+	/* Special case when user has set very strict latency requirement */
+	if (unlikely(latency_req == 0))
+		return 0;
+
+	/* determine the expected residency time, round up */
+	data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length());
+
+	get_iowait_load(&nr_iowaiters, &cpu_load);
+	data->bucket = which_bucket(data->next_timer_us, nr_iowaiters);
+
+	/*
+	 * Force the result of multiplication to be 64 bits even if both
+	 * operands are 32 bits.
+	 * Make sure to round up for half microseconds.
+	 */
+	data->predicted_us = DIV_ROUND_CLOSEST_ULL((uint64_t)data->next_timer_us *
+					 data->correction_factor[data->bucket],
+					 RESOLUTION * DECAY);
+
+	expected_interval = get_typical_interval(data);
+	expected_interval = min(expected_interval, data->next_timer_us);
+
+	if (CPUIDLE_DRIVER_STATE_START > 0) {
+		struct cpuidle_state *s = &drv->states[CPUIDLE_DRIVER_STATE_START];
+		unsigned int polling_threshold;
+
+		/*
+		 * We want to default to C1 (hlt), not to busy polling
+		 * unless the timer is happening really really soon, or
+		 * C1's exit latency exceeds the user configured limit.
+		 */
+		polling_threshold = max_t(unsigned int, 20, s->target_residency);
+		if (data->next_timer_us > polling_threshold &&
+		    latency_req > s->exit_latency && !s->disabled &&
+		    !dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable)
+			data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
+		else
+			data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1;
+	} else {
+		data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
+	}
+
+	/*
+	 * Use the lowest expected idle interval to pick the idle state.
+	 */
+	data->predicted_us = min(data->predicted_us, expected_interval);
+
+	/*
+	 * Use the performance multiplier and the user-configurable
+	 * latency_req to determine the maximum exit latency.
+	 */
+	interactivity_req = data->predicted_us / performance_multiplier(nr_iowaiters, cpu_load);
+	if (latency_req > interactivity_req)
+		latency_req = interactivity_req;
+
+	/*
+	 * Find the idle state with the lowest power while satisfying
+	 * our constraints.
+	 */
+	for (i = data->last_state_idx + 1; i < drv->state_count; i++) {
+		struct cpuidle_state *s = &drv->states[i];
+		struct cpuidle_state_usage *su = &dev->states_usage[i];
+
+		if (s->disabled || su->disable)
+			continue;
+		if (s->target_residency > data->predicted_us)
+			continue;
+		if (s->exit_latency > latency_req)
+			continue;
+
+		data->last_state_idx = i;
+	}
+
+	return data->last_state_idx;
+}
+
+/**
+ * menu_reflect - records that data structures need update
+ * @dev: the CPU
+ * @index: the index of actual entered state
+ *
+ * NOTE: it's important to be fast here because this operation will add to
+ *       the overall exit latency.
+ */
+static void menu_reflect(struct cpuidle_device *dev, int index)
+{
+	struct menu_device *data = this_cpu_ptr(&menu_devices);
+
+	data->last_state_idx = index;
+	data->needs_update = 1;
+}
+
+/**
+ * menu_update - attempts to guess what happened after entry
+ * @drv: cpuidle driver containing state data
+ * @dev: the CPU
+ */
+static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
+{
+	struct menu_device *data = this_cpu_ptr(&menu_devices);
+	int last_idx = data->last_state_idx;
+	struct cpuidle_state *target = &drv->states[last_idx];
+	unsigned int measured_us;
+	unsigned int new_factor;
+
+	/*
+	 * Try to figure out how much time passed between entry to low
+	 * power state and occurrence of the wakeup event.
+	 *
+	 * If the entered idle state didn't support residency measurements,
+	 * we use them anyway if they are short, and if long,
+	 * truncate to the whole expected time.
+	 *
+	 * Any measured amount of time will include the exit latency.
+	 * Since we are interested in when the wakeup begun, not when it
+	 * was completed, we must subtract the exit latency. However, if
+	 * the measured amount of time is less than the exit latency,
+	 * 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;
+
+	/* Make sure our coefficients do not exceed unity */
+	if (measured_us > data->next_timer_us)
+		measured_us = data->next_timer_us;
+
+	/* Update our correction ratio */
+	new_factor = data->correction_factor[data->bucket];
+	new_factor -= new_factor / DECAY;
+
+	if (data->next_timer_us > 0 && measured_us < MAX_INTERESTING)
+		new_factor += RESOLUTION * measured_us / data->next_timer_us;
+	else
+		/*
+		 * we were idle so long that we count it as a perfect
+		 * prediction
+		 */
+		new_factor += RESOLUTION;
+
+	/*
+	 * We don't want 0 as factor; we always want at least
+	 * a tiny bit of estimated time. Fortunately, due to rounding,
+	 * new_factor will stay nonzero regardless of measured_us values
+	 * and the compiler can eliminate this test as long as DECAY > 1.
+	 */
+	if (DECAY == 1 && unlikely(new_factor == 0))
+		new_factor = 1;
+
+	data->correction_factor[data->bucket] = new_factor;
+
+	/* update the repeating-pattern data */
+	data->intervals[data->interval_ptr++] = measured_us;
+	if (data->interval_ptr >= INTERVALS)
+		data->interval_ptr = 0;
+}
+
+/**
+ * menu_enable_device - scans a CPU's states and does setup
+ * @drv: cpuidle driver
+ * @dev: the CPU
+ */
+static int menu_enable_device(struct cpuidle_driver *drv,
+				struct cpuidle_device *dev)
+{
+	struct menu_device *data = &per_cpu(menu_devices, dev->cpu);
+	int i;
+
+	memset(data, 0, sizeof(struct menu_device));
+
+	/*
+	 * if the correction factor is 0 (eg first time init or cpu hotplug
+	 * etc), we actually want to start out with a unity factor.
+	 */
+	for(i = 0; i < BUCKETS; i++)
+		data->correction_factor[i] = RESOLUTION * DECAY;
+
+	return 0;
+}
+
+static struct cpuidle_governor menu_governor = {
+	.name =		"menu",
+	.rating =	20,
+	.enable =	menu_enable_device,
+	.select =	menu_select,
+	.reflect =	menu_reflect,
+};
+
+/**
+ * init_menu - initializes the governor
+ */
+static int __init init_menu(void)
+{
+	return cpuidle_register_governor(&menu_governor);
+}
+
+postcore_initcall(init_menu);
diff --git a/drivers/cpuidle/governors/Makefile b/drivers/cpuidle/governors/Makefile
deleted file mode 100644
index 1b51272..0000000
--- a/drivers/cpuidle/governors/Makefile
+++ /dev/null
@@ -1,6 +0,0 @@
-#
-# Makefile for cpuidle governors.
-#
-
-obj-$(CONFIG_CPU_IDLE_GOV_LADDER) += ladder.o
-obj-$(CONFIG_CPU_IDLE_GOV_MENU) += menu.o
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
deleted file mode 100644
index fe8f089..0000000
--- a/drivers/cpuidle/governors/ladder.c
+++ /dev/null
@@ -1,197 +0,0 @@
-/*
- * ladder.c - the residency ladder algorithm
- *
- *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@...el.com>
- *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@...el.com>
- *  Copyright (C) 2004, 2005 Dominik Brodowski <linux@...do.de>
- *
- * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
- *               Shaohua Li <shaohua.li@...el.com>
- *               Adam Belay <abelay@...ell.com>
- *
- * This code is licenced under the GPL.
- */
-
-#include <linux/kernel.h>
-#include <linux/cpuidle.h>
-#include <linux/pm_qos.h>
-#include <linux/jiffies.h>
-#include <linux/tick.h>
-
-#include <asm/io.h>
-#include <asm/uaccess.h>
-
-#define PROMOTION_COUNT 4
-#define DEMOTION_COUNT 1
-
-struct ladder_device_state {
-	struct {
-		u32 promotion_count;
-		u32 demotion_count;
-		u32 promotion_time;
-		u32 demotion_time;
-	} threshold;
-	struct {
-		int promotion_count;
-		int demotion_count;
-	} stats;
-};
-
-struct ladder_device {
-	struct ladder_device_state states[CPUIDLE_STATE_MAX];
-	int last_state_idx;
-};
-
-static DEFINE_PER_CPU(struct ladder_device, ladder_devices);
-
-/**
- * ladder_do_selection - prepares private data for a state change
- * @ldev: the ladder device
- * @old_idx: the current state index
- * @new_idx: the new target state index
- */
-static inline void ladder_do_selection(struct ladder_device *ldev,
-				       int old_idx, int new_idx)
-{
-	ldev->states[old_idx].stats.promotion_count = 0;
-	ldev->states[old_idx].stats.demotion_count = 0;
-	ldev->last_state_idx = new_idx;
-}
-
-/**
- * ladder_select_state - selects the next state to enter
- * @drv: cpuidle driver
- * @dev: the CPU
- */
-static int ladder_select_state(struct cpuidle_driver *drv,
-				struct cpuidle_device *dev)
-{
-	struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
-	struct ladder_device_state *last_state;
-	int last_residency, last_idx = ldev->last_state_idx;
-	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
-
-	/* Special case when user has set very strict latency requirement */
-	if (unlikely(latency_req == 0)) {
-		ladder_do_selection(ldev, last_idx, 0);
-		return 0;
-	}
-
-	last_state = &ldev->states[last_idx];
-
-	last_residency = cpuidle_get_last_residency(dev) - drv->states[last_idx].exit_latency;
-
-	/* consider promotion */
-	if (last_idx < drv->state_count - 1 &&
-	    !drv->states[last_idx + 1].disabled &&
-	    !dev->states_usage[last_idx + 1].disable &&
-	    last_residency > last_state->threshold.promotion_time &&
-	    drv->states[last_idx + 1].exit_latency <= latency_req) {
-		last_state->stats.promotion_count++;
-		last_state->stats.demotion_count = 0;
-		if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) {
-			ladder_do_selection(ldev, last_idx, last_idx + 1);
-			return last_idx + 1;
-		}
-	}
-
-	/* consider demotion */
-	if (last_idx > CPUIDLE_DRIVER_STATE_START &&
-	    (drv->states[last_idx].disabled ||
-	    dev->states_usage[last_idx].disable ||
-	    drv->states[last_idx].exit_latency > latency_req)) {
-		int i;
-
-		for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) {
-			if (drv->states[i].exit_latency <= latency_req)
-				break;
-		}
-		ladder_do_selection(ldev, last_idx, i);
-		return i;
-	}
-
-	if (last_idx > CPUIDLE_DRIVER_STATE_START &&
-	    last_residency < last_state->threshold.demotion_time) {
-		last_state->stats.demotion_count++;
-		last_state->stats.promotion_count = 0;
-		if (last_state->stats.demotion_count >= last_state->threshold.demotion_count) {
-			ladder_do_selection(ldev, last_idx, last_idx - 1);
-			return last_idx - 1;
-		}
-	}
-
-	/* otherwise remain at the current state */
-	return last_idx;
-}
-
-/**
- * ladder_enable_device - setup for the governor
- * @drv: cpuidle driver
- * @dev: the CPU
- */
-static int ladder_enable_device(struct cpuidle_driver *drv,
-				struct cpuidle_device *dev)
-{
-	int i;
-	struct ladder_device *ldev = &per_cpu(ladder_devices, dev->cpu);
-	struct ladder_device_state *lstate;
-	struct cpuidle_state *state;
-
-	ldev->last_state_idx = CPUIDLE_DRIVER_STATE_START;
-
-	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
-		state = &drv->states[i];
-		lstate = &ldev->states[i];
-
-		lstate->stats.promotion_count = 0;
-		lstate->stats.demotion_count = 0;
-
-		lstate->threshold.promotion_count = PROMOTION_COUNT;
-		lstate->threshold.demotion_count = DEMOTION_COUNT;
-
-		if (i < drv->state_count - 1)
-			lstate->threshold.promotion_time = state->exit_latency;
-		if (i > CPUIDLE_DRIVER_STATE_START)
-			lstate->threshold.demotion_time = state->exit_latency;
-	}
-
-	return 0;
-}
-
-/**
- * ladder_reflect - update the correct last_state_idx
- * @dev: the CPU
- * @index: the index of actual state entered
- */
-static void ladder_reflect(struct cpuidle_device *dev, int index)
-{
-	struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
-	if (index > 0)
-		ldev->last_state_idx = index;
-}
-
-static struct cpuidle_governor ladder_governor = {
-	.name =		"ladder",
-	.rating =	10,
-	.enable =	ladder_enable_device,
-	.select =	ladder_select_state,
-	.reflect =	ladder_reflect,
-};
-
-/**
- * init_ladder - initializes the governor
- */
-static int __init init_ladder(void)
-{
-	/*
-	 * When NO_HZ is disabled, or when booting with nohz=off, the ladder
-	 * governor is better so give it a higher rating than the menu
-	 * governor.
-	 */
-	if (!tick_nohz_enabled)
-		ladder_governor.rating = 25;
-
-	return cpuidle_register_governor(&ladder_governor);
-}
-
-postcore_initcall(init_ladder);
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
deleted file mode 100644
index d9b5b93..0000000
--- a/drivers/cpuidle/governors/menu.c
+++ /dev/null
@@ -1,496 +0,0 @@
-/*
- * menu.c - the menu idle governor
- *
- * Copyright (C) 2006-2007 Adam Belay <abelay@...ell.com>
- * Copyright (C) 2009 Intel Corporation
- * Author:
- *        Arjan van de Ven <arjan@...ux.intel.com>
- *
- * This code is licenced under the GPL version 2 as described
- * in the COPYING file that acompanies the Linux Kernel.
- */
-
-#include <linux/kernel.h>
-#include <linux/cpuidle.h>
-#include <linux/pm_qos.h>
-#include <linux/time.h>
-#include <linux/ktime.h>
-#include <linux/hrtimer.h>
-#include <linux/tick.h>
-#include <linux/sched.h>
-#include <linux/math64.h>
-
-/*
- * Please note when changing the tuning values:
- * If (MAX_INTERESTING-1) * RESOLUTION > UINT_MAX, the result of
- * a scaling operation multiplication may overflow on 32 bit platforms.
- * In that case, #define RESOLUTION as ULL to get 64 bit result:
- * #define RESOLUTION 1024ULL
- *
- * The default values do not overflow.
- */
-#define BUCKETS 12
-#define INTERVAL_SHIFT 3
-#define INTERVALS (1UL << INTERVAL_SHIFT)
-#define RESOLUTION 1024
-#define DECAY 8
-#define MAX_INTERESTING 50000
-
-
-/*
- * Concepts and ideas behind the menu governor
- *
- * For the menu governor, there are 3 decision factors for picking a C
- * state:
- * 1) Energy break even point
- * 2) Performance impact
- * 3) Latency tolerance (from pmqos infrastructure)
- * These these three factors are treated independently.
- *
- * Energy break even point
- * -----------------------
- * C state entry and exit have an energy cost, and a certain amount of time in
- * the  C state is required to actually break even on this cost. CPUIDLE
- * provides us this duration in the "target_residency" field. So all that we
- * need is a good prediction of how long we'll be idle. Like the traditional
- * menu governor, we start with the actual known "next timer event" time.
- *
- * Since there are other source of wakeups (interrupts for example) than
- * the next timer event, this estimation is rather optimistic. To get a
- * more realistic estimate, a correction factor is applied to the estimate,
- * that is based on historic behavior. For example, if in the past the actual
- * duration always was 50% of the next timer tick, the correction factor will
- * be 0.5.
- *
- * menu uses a running average for this correction factor, however it uses a
- * set of factors, not just a single factor. This stems from the realization
- * that the ratio is dependent on the order of magnitude of the expected
- * duration; if we expect 500 milliseconds of idle time the likelihood of
- * getting an interrupt very early is much higher than if we expect 50 micro
- * seconds of idle time. A second independent factor that has big impact on
- * the actual factor is if there is (disk) IO outstanding or not.
- * (as a special twist, we consider every sleep longer than 50 milliseconds
- * as perfect; there are no power gains for sleeping longer than this)
- *
- * For these two reasons we keep an array of 12 independent factors, that gets
- * indexed based on the magnitude of the expected duration as well as the
- * "is IO outstanding" property.
- *
- * Repeatable-interval-detector
- * ----------------------------
- * There are some cases where "next timer" is a completely unusable predictor:
- * Those cases where the interval is fixed, for example due to hardware
- * interrupt mitigation, but also due to fixed transfer rate devices such as
- * mice.
- * For this, we use a different predictor: We track the duration of the last 8
- * intervals and if the stand deviation of these 8 intervals is below a
- * threshold value, we use the average of these intervals as prediction.
- *
- * Limiting Performance Impact
- * ---------------------------
- * C states, especially those with large exit latencies, can have a real
- * noticeable impact on workloads, which is not acceptable for most sysadmins,
- * and in addition, less performance has a power price of its own.
- *
- * As a general rule of thumb, menu assumes that the following heuristic
- * holds:
- *     The busier the system, the less impact of C states is acceptable
- *
- * This rule-of-thumb is implemented using a performance-multiplier:
- * If the exit latency times the performance multiplier is longer than
- * the predicted duration, the C state is not considered a candidate
- * for selection due to a too high performance impact. So the higher
- * this multiplier is, the longer we need to be idle to pick a deep C
- * state, and thus the less likely a busy CPU will hit such a deep
- * C state.
- *
- * Two factors are used in determing this multiplier:
- * a value of 10 is added for each point of "per cpu load average" we have.
- * a value of 5 points is added for each process that is waiting for
- * IO on this CPU.
- * (these values are experimentally determined)
- *
- * The load average factor gives a longer term (few seconds) input to the
- * decision, while the iowait value gives a cpu local instantanious input.
- * The iowait factor may look low, but realize that this is also already
- * represented in the system load average.
- *
- */
-
-struct menu_device {
-	int		last_state_idx;
-	int             needs_update;
-
-	unsigned int	next_timer_us;
-	unsigned int	predicted_us;
-	unsigned int	bucket;
-	unsigned int	correction_factor[BUCKETS];
-	unsigned int	intervals[INTERVALS];
-	int		interval_ptr;
-};
-
-
-#define LOAD_INT(x) ((x) >> FSHIFT)
-#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
-
-static inline int get_loadavg(unsigned long load)
-{
-	return LOAD_INT(load) * 10 + LOAD_FRAC(load) / 10;
-}
-
-static inline int which_bucket(unsigned int duration, unsigned long nr_iowaiters)
-{
-	int bucket = 0;
-
-	/*
-	 * We keep two groups of stats; one with no
-	 * IO pending, one without.
-	 * This allows us to calculate
-	 * E(duration)|iowait
-	 */
-	if (nr_iowaiters)
-		bucket = BUCKETS/2;
-
-	if (duration < 10)
-		return bucket;
-	if (duration < 100)
-		return bucket + 1;
-	if (duration < 1000)
-		return bucket + 2;
-	if (duration < 10000)
-		return bucket + 3;
-	if (duration < 100000)
-		return bucket + 4;
-	return bucket + 5;
-}
-
-/*
- * Return a multiplier for the exit latency that is intended
- * to take performance requirements into account.
- * The more performance critical we estimate the system
- * to be, the higher this multiplier, and thus the higher
- * the barrier to go to an expensive C state.
- */
-static inline int performance_multiplier(unsigned long nr_iowaiters, unsigned long load)
-{
-	int mult = 1;
-
-	/* for higher loadavg, we are more reluctant */
-
-	mult += 2 * get_loadavg(load);
-
-	/* for IO wait tasks (per cpu!) we add 5x each */
-	mult += 10 * nr_iowaiters;
-
-	return mult;
-}
-
-static DEFINE_PER_CPU(struct menu_device, menu_devices);
-
-static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev);
-
-/*
- * Try detecting repeating patterns by keeping track of the last 8
- * intervals, and checking if the standard deviation of that set
- * of points is below a threshold. If it is... then use the
- * average of these 8 points as the estimated value.
- */
-static unsigned int get_typical_interval(struct menu_device *data)
-{
-	int i, divisor;
-	unsigned int max, thresh, avg;
-	uint64_t sum, variance;
-
-	thresh = UINT_MAX; /* Discard outliers above this value */
-
-again:
-
-	/* First calculate the average of past intervals */
-	max = 0;
-	sum = 0;
-	divisor = 0;
-	for (i = 0; i < INTERVALS; i++) {
-		unsigned int value = data->intervals[i];
-		if (value <= thresh) {
-			sum += value;
-			divisor++;
-			if (value > max)
-				max = value;
-		}
-	}
-	if (divisor == INTERVALS)
-		avg = sum >> INTERVAL_SHIFT;
-	else
-		avg = div_u64(sum, divisor);
-
-	/* Then try to determine variance */
-	variance = 0;
-	for (i = 0; i < INTERVALS; i++) {
-		unsigned int value = data->intervals[i];
-		if (value <= thresh) {
-			int64_t diff = (int64_t)value - avg;
-			variance += diff * diff;
-		}
-	}
-	if (divisor == INTERVALS)
-		variance >>= INTERVAL_SHIFT;
-	else
-		do_div(variance, divisor);
-
-	/*
-	 * The typical interval is obtained when standard deviation is
-	 * small (stddev <= 20 us, variance <= 400 us^2) or standard
-	 * deviation is small compared to the average interval (avg >
-	 * 6*stddev, avg^2 > 36*variance). The average is smaller than
-	 * UINT_MAX aka U32_MAX, so computing its square does not
-	 * overflow a u64. We simply reject this candidate average if
-	 * the standard deviation is greater than 715 s (which is
-	 * rather unlikely).
-	 *
-	 * Use this result only if there is no timer to wake us up sooner.
-	 */
-	if (likely(variance <= U64_MAX/36)) {
-		if ((((u64)avg*avg > variance*36) && (divisor * 4 >= INTERVALS * 3))
-							|| variance <= 400) {
-			return avg;
-		}
-	}
-
-	/*
-	 * If we have outliers to the upside in our distribution, discard
-	 * those by setting the threshold to exclude these outliers, then
-	 * calculate the average and standard deviation again. Once we get
-	 * down to the bottom 3/4 of our samples, stop excluding samples.
-	 *
-	 * This can deal with workloads that have long pauses interspersed
-	 * with sporadic activity with a bunch of short pauses.
-	 */
-	if ((divisor * 4) <= INTERVALS * 3)
-		return UINT_MAX;
-
-	thresh = max - 1;
-	goto again;
-}
-
-/**
- * menu_select - selects the next idle state to enter
- * @drv: cpuidle driver containing state data
- * @dev: the CPU
- */
-static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
-{
-	struct menu_device *data = this_cpu_ptr(&menu_devices);
-	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
-	int i;
-	unsigned int interactivity_req;
-	unsigned int expected_interval;
-	unsigned long nr_iowaiters, cpu_load;
-
-	if (data->needs_update) {
-		menu_update(drv, dev);
-		data->needs_update = 0;
-	}
-
-	/* Special case when user has set very strict latency requirement */
-	if (unlikely(latency_req == 0))
-		return 0;
-
-	/* determine the expected residency time, round up */
-	data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length());
-
-	get_iowait_load(&nr_iowaiters, &cpu_load);
-	data->bucket = which_bucket(data->next_timer_us, nr_iowaiters);
-
-	/*
-	 * Force the result of multiplication to be 64 bits even if both
-	 * operands are 32 bits.
-	 * Make sure to round up for half microseconds.
-	 */
-	data->predicted_us = DIV_ROUND_CLOSEST_ULL((uint64_t)data->next_timer_us *
-					 data->correction_factor[data->bucket],
-					 RESOLUTION * DECAY);
-
-	expected_interval = get_typical_interval(data);
-	expected_interval = min(expected_interval, data->next_timer_us);
-
-	if (CPUIDLE_DRIVER_STATE_START > 0) {
-		struct cpuidle_state *s = &drv->states[CPUIDLE_DRIVER_STATE_START];
-		unsigned int polling_threshold;
-
-		/*
-		 * We want to default to C1 (hlt), not to busy polling
-		 * unless the timer is happening really really soon, or
-		 * C1's exit latency exceeds the user configured limit.
-		 */
-		polling_threshold = max_t(unsigned int, 20, s->target_residency);
-		if (data->next_timer_us > polling_threshold &&
-		    latency_req > s->exit_latency && !s->disabled &&
-		    !dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable)
-			data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
-		else
-			data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1;
-	} else {
-		data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
-	}
-
-	/*
-	 * Use the lowest expected idle interval to pick the idle state.
-	 */
-	data->predicted_us = min(data->predicted_us, expected_interval);
-
-	/*
-	 * Use the performance multiplier and the user-configurable
-	 * latency_req to determine the maximum exit latency.
-	 */
-	interactivity_req = data->predicted_us / performance_multiplier(nr_iowaiters, cpu_load);
-	if (latency_req > interactivity_req)
-		latency_req = interactivity_req;
-
-	/*
-	 * Find the idle state with the lowest power while satisfying
-	 * our constraints.
-	 */
-	for (i = data->last_state_idx + 1; i < drv->state_count; i++) {
-		struct cpuidle_state *s = &drv->states[i];
-		struct cpuidle_state_usage *su = &dev->states_usage[i];
-
-		if (s->disabled || su->disable)
-			continue;
-		if (s->target_residency > data->predicted_us)
-			continue;
-		if (s->exit_latency > latency_req)
-			continue;
-
-		data->last_state_idx = i;
-	}
-
-	return data->last_state_idx;
-}
-
-/**
- * menu_reflect - records that data structures need update
- * @dev: the CPU
- * @index: the index of actual entered state
- *
- * NOTE: it's important to be fast here because this operation will add to
- *       the overall exit latency.
- */
-static void menu_reflect(struct cpuidle_device *dev, int index)
-{
-	struct menu_device *data = this_cpu_ptr(&menu_devices);
-
-	data->last_state_idx = index;
-	data->needs_update = 1;
-}
-
-/**
- * menu_update - attempts to guess what happened after entry
- * @drv: cpuidle driver containing state data
- * @dev: the CPU
- */
-static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
-{
-	struct menu_device *data = this_cpu_ptr(&menu_devices);
-	int last_idx = data->last_state_idx;
-	struct cpuidle_state *target = &drv->states[last_idx];
-	unsigned int measured_us;
-	unsigned int new_factor;
-
-	/*
-	 * Try to figure out how much time passed between entry to low
-	 * power state and occurrence of the wakeup event.
-	 *
-	 * If the entered idle state didn't support residency measurements,
-	 * we use them anyway if they are short, and if long,
-	 * truncate to the whole expected time.
-	 *
-	 * Any measured amount of time will include the exit latency.
-	 * Since we are interested in when the wakeup begun, not when it
-	 * was completed, we must subtract the exit latency. However, if
-	 * the measured amount of time is less than the exit latency,
-	 * 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;
-
-	/* Make sure our coefficients do not exceed unity */
-	if (measured_us > data->next_timer_us)
-		measured_us = data->next_timer_us;
-
-	/* Update our correction ratio */
-	new_factor = data->correction_factor[data->bucket];
-	new_factor -= new_factor / DECAY;
-
-	if (data->next_timer_us > 0 && measured_us < MAX_INTERESTING)
-		new_factor += RESOLUTION * measured_us / data->next_timer_us;
-	else
-		/*
-		 * we were idle so long that we count it as a perfect
-		 * prediction
-		 */
-		new_factor += RESOLUTION;
-
-	/*
-	 * We don't want 0 as factor; we always want at least
-	 * a tiny bit of estimated time. Fortunately, due to rounding,
-	 * new_factor will stay nonzero regardless of measured_us values
-	 * and the compiler can eliminate this test as long as DECAY > 1.
-	 */
-	if (DECAY == 1 && unlikely(new_factor == 0))
-		new_factor = 1;
-
-	data->correction_factor[data->bucket] = new_factor;
-
-	/* update the repeating-pattern data */
-	data->intervals[data->interval_ptr++] = measured_us;
-	if (data->interval_ptr >= INTERVALS)
-		data->interval_ptr = 0;
-}
-
-/**
- * menu_enable_device - scans a CPU's states and does setup
- * @drv: cpuidle driver
- * @dev: the CPU
- */
-static int menu_enable_device(struct cpuidle_driver *drv,
-				struct cpuidle_device *dev)
-{
-	struct menu_device *data = &per_cpu(menu_devices, dev->cpu);
-	int i;
-
-	memset(data, 0, sizeof(struct menu_device));
-
-	/*
-	 * if the correction factor is 0 (eg first time init or cpu hotplug
-	 * etc), we actually want to start out with a unity factor.
-	 */
-	for(i = 0; i < BUCKETS; i++)
-		data->correction_factor[i] = RESOLUTION * DECAY;
-
-	return 0;
-}
-
-static struct cpuidle_governor menu_governor = {
-	.name =		"menu",
-	.rating =	20,
-	.enable =	menu_enable_device,
-	.select =	menu_select,
-	.reflect =	menu_reflect,
-};
-
-/**
- * init_menu - initializes the governor
- */
-static int __init init_menu(void)
-{
-	return cpuidle_register_governor(&menu_governor);
-}
-
-postcore_initcall(init_menu);
-- 
1.9.1

Powered by blists - more mailing lists