Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 892 insertions, 0 deletions

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
new file mode 100644
index 000000000..60f0e0e04
--- /dev/null
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -0,0 +1,892 @@
+/*
+ * CPUFreq governor based on scheduler-provided CPU utilization data.
+ *
+ * Copyright (C) 2016, Intel Corporation
+ * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include "sched.h"
+
+#include <trace/events/power.h>
+
+struct sugov_tunables {
+	struct gov_attr_set	attr_set;
+	unsigned int		rate_limit_us;
+};
+
+struct sugov_policy {
+	struct cpufreq_policy	*policy;
+
+	struct sugov_tunables	*tunables;
+	struct list_head	tunables_hook;
+
+	raw_spinlock_t		update_lock;	/* For shared policies */
+	u64			last_freq_update_time;
+	s64			freq_update_delay_ns;
+	unsigned int		next_freq;
+	unsigned int		cached_raw_freq;
+
+	/* The next fields are only needed if fast switch cannot be used: */
+	struct			irq_work irq_work;
+	struct			kthread_work work;
+	struct			mutex work_lock;
+	struct			kthread_worker worker;
+	struct task_struct	*thread;
+	bool			work_in_progress;
+
+	bool			limits_changed;
+	bool			need_freq_update;
+};
+
+struct sugov_cpu {
+	struct update_util_data	update_util;
+	struct sugov_policy	*sg_policy;
+	unsigned int		cpu;
+
+	bool			iowait_boost_pending;
+	unsigned int		iowait_boost;
+	u64			last_update;
+
+	unsigned long		bw_dl;
+	unsigned long		min;
+	unsigned long		max;
+
+	/* The field below is for single-CPU policies only: */
+#ifdef CONFIG_NO_HZ_COMMON
+	unsigned long		saved_idle_calls;
+#endif
+};
+
+static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
+
+/************************ Governor internals ***********************/
+
+static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
+{
+	s64 delta_ns;
+
+	/*
+	 * Since cpufreq_update_util() is called with rq->lock held for
+	 * the @target_cpu, our per-CPU data is fully serialized.
+	 *
+	 * However, drivers cannot in general deal with cross-CPU
+	 * requests, so while get_next_freq() will work, our
+	 * sugov_update_commit() call may not for the fast switching platforms.
+	 *
+	 * Hence stop here for remote requests if they aren't supported
+	 * by the hardware, as calculating the frequency is pointless if
+	 * we cannot in fact act on it.
+	 *
+	 * This is needed on the slow switching platforms too to prevent CPUs
+	 * going offline from leaving stale IRQ work items behind.
+	 */
+	if (!cpufreq_this_cpu_can_update(sg_policy->policy))
+		return false;
+
+	if (unlikely(sg_policy->limits_changed)) {
+		sg_policy->limits_changed = false;
+		sg_policy->need_freq_update = true;
+		return true;
+	}
+
+	delta_ns = time - sg_policy->last_freq_update_time;
+
+	return delta_ns >= sg_policy->freq_update_delay_ns;
+}
+
+static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
+				   unsigned int next_freq)
+{
+	if (sg_policy->next_freq == next_freq)
+		return false;
+
+	sg_policy->next_freq = next_freq;
+	sg_policy->last_freq_update_time = time;
+
+	return true;
+}
+
+static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
+			      unsigned int next_freq)
+{
+	struct cpufreq_policy *policy = sg_policy->policy;
+	int cpu;
+
+	if (!sugov_update_next_freq(sg_policy, time, next_freq))
+		return;
+
+	next_freq = cpufreq_driver_fast_switch(policy, next_freq);
+	if (!next_freq)
+		return;
+
+	policy->cur = next_freq;
+
+	if (trace_cpu_frequency_enabled()) {
+		for_each_cpu(cpu, policy->cpus)
+			trace_cpu_frequency(next_freq, cpu);
+	}
+}
+
+static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
+				  unsigned int next_freq)
+{
+	if (!sugov_update_next_freq(sg_policy, time, next_freq))
+		return;
+
+	if (!sg_policy->work_in_progress) {
+		sg_policy->work_in_progress = true;
+		irq_work_queue(&sg_policy->irq_work);
+	}
+}
+
+/**
+ * get_next_freq - Compute a new frequency for a given cpufreq policy.
+ * @sg_policy: schedutil policy object to compute the new frequency for.
+ * @util: Current CPU utilization.
+ * @max: CPU capacity.
+ *
+ * If the utilization is frequency-invariant, choose the new frequency to be
+ * proportional to it, that is
+ *
+ * next_freq = C * max_freq * util / max
+ *
+ * Otherwise, approximate the would-be frequency-invariant utilization by
+ * util_raw * (curr_freq / max_freq) which leads to
+ *
+ * next_freq = C * curr_freq * util_raw / max
+ *
+ * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
+ *
+ * The lowest driver-supported frequency which is equal or greater than the raw
+ * next_freq (as calculated above) is returned, subject to policy min/max and
+ * cpufreq driver limitations.
+ */
+static unsigned int get_next_freq(struct sugov_policy *sg_policy,
+				  unsigned long util, unsigned long max)
+{
+	struct cpufreq_policy *policy = sg_policy->policy;
+	unsigned int freq = arch_scale_freq_invariant() ?
+				policy->cpuinfo.max_freq : policy->cur;
+
+	freq = (freq + (freq >> 2)) * util / max;
+
+	if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
+		return sg_policy->next_freq;
+
+	sg_policy->need_freq_update = false;
+	sg_policy->cached_raw_freq = freq;
+	return cpufreq_driver_resolve_freq(policy, freq);
+}
+
+/*
+ * This function computes an effective utilization for the given CPU, to be
+ * used for frequency selection given the linear relation: f = u * f_max.
+ *
+ * The scheduler tracks the following metrics:
+ *
+ *   cpu_util_{cfs,rt,dl,irq}()
+ *   cpu_bw_dl()
+ *
+ * Where the cfs,rt and dl util numbers are tracked with the same metric and
+ * synchronized windows and are thus directly comparable.
+ *
+ * The cfs,rt,dl utilization are the running times measured with rq->clock_task
+ * which excludes things like IRQ and steal-time. These latter are then accrued
+ * in the irq utilization.
+ *
+ * The DL bandwidth number otoh is not a measured metric but a value computed
+ * based on the task model parameters and gives the minimal utilization
+ * required to meet deadlines.
+ */
+static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)
+{
+	struct rq *rq = cpu_rq(sg_cpu->cpu);
+	unsigned long util, irq, max;
+
+	sg_cpu->max = max = arch_scale_cpu_capacity(NULL, sg_cpu->cpu);
+	sg_cpu->bw_dl = cpu_bw_dl(rq);
+
+	if (rt_rq_is_runnable(&rq->rt))
+		return max;
+
+	/*
+	 * Early check to see if IRQ/steal time saturates the CPU, can be
+	 * because of inaccuracies in how we track these -- see
+	 * update_irq_load_avg().
+	 */
+	irq = cpu_util_irq(rq);
+	if (unlikely(irq >= max))
+		return max;
+
+	/*
+	 * Because the time spend on RT/DL tasks is visible as 'lost' time to
+	 * CFS tasks and we use the same metric to track the effective
+	 * utilization (PELT windows are synchronized) we can directly add them
+	 * to obtain the CPU's actual utilization.
+	 */
+	util = cpu_util_cfs(rq);
+	util += cpu_util_rt(rq);
+
+	/*
+	 * We do not make cpu_util_dl() a permanent part of this sum because we
+	 * want to use cpu_bw_dl() later on, but we need to check if the
+	 * CFS+RT+DL sum is saturated (ie. no idle time) such that we select
+	 * f_max when there is no idle time.
+	 *
+	 * NOTE: numerical errors or stop class might cause us to not quite hit
+	 * saturation when we should -- something for later.
+	 */
+	if ((util + cpu_util_dl(rq)) >= max)
+		return max;
+
+	/*
+	 * There is still idle time; further improve the number by using the
+	 * irq metric. Because IRQ/steal time is hidden from the task clock we
+	 * need to scale the task numbers:
+	 *
+	 *              1 - irq
+	 *   U' = irq + ------- * U
+	 *                max
+	 */
+	util = scale_irq_capacity(util, irq, max);
+	util += irq;
+
+	/*
+	 * Bandwidth required by DEADLINE must always be granted while, for
+	 * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
+	 * to gracefully reduce the frequency when no tasks show up for longer
+	 * periods of time.
+	 *
+	 * Ideally we would like to set bw_dl as min/guaranteed freq and util +
+	 * bw_dl as requested freq. However, cpufreq is not yet ready for such
+	 * an interface. So, we only do the latter for now.
+	 */
+	return min(max, util + sg_cpu->bw_dl);
+}
+
+/**
+ * sugov_iowait_reset() - Reset the IO boost status of a CPU.
+ * @sg_cpu: the sugov data for the CPU to boost
+ * @time: the update time from the caller
+ * @set_iowait_boost: true if an IO boost has been requested
+ *
+ * The IO wait boost of a task is disabled after a tick since the last update
+ * of a CPU. If a new IO wait boost is requested after more then a tick, then
+ * we enable the boost starting from the minimum frequency, which improves
+ * energy efficiency by ignoring sporadic wakeups from IO.
+ */
+static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
+			       bool set_iowait_boost)
+{
+	s64 delta_ns = time - sg_cpu->last_update;
+
+	/* Reset boost only if a tick has elapsed since last request */
+	if (delta_ns <= TICK_NSEC)
+		return false;
+
+	sg_cpu->iowait_boost = set_iowait_boost ? sg_cpu->min : 0;
+	sg_cpu->iowait_boost_pending = set_iowait_boost;
+
+	return true;
+}
+
+/**
+ * sugov_iowait_boost() - Updates the IO boost status of a CPU.
+ * @sg_cpu: the sugov data for the CPU to boost
+ * @time: the update time from the caller
+ * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
+ *
+ * Each time a task wakes up after an IO operation, the CPU utilization can be
+ * boosted to a certain utilization which doubles at each "frequent and
+ * successive" wakeup from IO, ranging from the utilization of the minimum
+ * OPP to the utilization of the maximum OPP.
+ * To keep doubling, an IO boost has to be requested at least once per tick,
+ * otherwise we restart from the utilization of the minimum OPP.
+ */
+static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
+			       unsigned int flags)
+{
+	bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
+
+	/* Reset boost if the CPU appears to have been idle enough */
+	if (sg_cpu->iowait_boost &&
+	    sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
+		return;
+
+	/* Boost only tasks waking up after IO */
+	if (!set_iowait_boost)
+		return;
+
+	/* Ensure boost doubles only one time at each request */
+	if (sg_cpu->iowait_boost_pending)
+		return;
+	sg_cpu->iowait_boost_pending = true;
+
+	/* Double the boost at each request */
+	if (sg_cpu->iowait_boost) {
+		sg_cpu->iowait_boost =
+			min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
+		return;
+	}
+
+	/* First wakeup after IO: start with minimum boost */
+	sg_cpu->iowait_boost = sg_cpu->min;
+}
+
+/**
+ * sugov_iowait_apply() - Apply the IO boost to a CPU.
+ * @sg_cpu: the sugov data for the cpu to boost
+ * @time: the update time from the caller
+ * @util: the utilization to (eventually) boost
+ * @max: the maximum value the utilization can be boosted to
+ *
+ * A CPU running a task which woken up after an IO operation can have its
+ * utilization boosted to speed up the completion of those IO operations.
+ * The IO boost value is increased each time a task wakes up from IO, in
+ * sugov_iowait_apply(), and it's instead decreased by this function,
+ * each time an increase has not been requested (!iowait_boost_pending).
+ *
+ * A CPU which also appears to have been idle for at least one tick has also
+ * its IO boost utilization reset.
+ *
+ * This mechanism is designed to boost high frequently IO waiting tasks, while
+ * being more conservative on tasks which does sporadic IO operations.
+ */
+static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
+					unsigned long util, unsigned long max)
+{
+	unsigned long boost;
+
+	/* No boost currently required */
+	if (!sg_cpu->iowait_boost)
+		return util;
+
+	/* Reset boost if the CPU appears to have been idle enough */
+	if (sugov_iowait_reset(sg_cpu, time, false))
+		return util;
+
+	if (!sg_cpu->iowait_boost_pending) {
+		/*
+		 * No boost pending; reduce the boost value.
+		 */
+		sg_cpu->iowait_boost >>= 1;
+		if (sg_cpu->iowait_boost < sg_cpu->min) {
+			sg_cpu->iowait_boost = 0;
+			return util;
+		}
+	}
+
+	sg_cpu->iowait_boost_pending = false;
+
+	/*
+	 * @util is already in capacity scale; convert iowait_boost
+	 * into the same scale so we can compare.
+	 */
+	boost = (sg_cpu->iowait_boost * max) >> SCHED_CAPACITY_SHIFT;
+	return max(boost, util);
+}
+
+#ifdef CONFIG_NO_HZ_COMMON
+static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
+{
+	unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
+	bool ret = idle_calls == sg_cpu->saved_idle_calls;
+
+	sg_cpu->saved_idle_calls = idle_calls;
+	return ret;
+}
+#else
+static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
+#endif /* CONFIG_NO_HZ_COMMON */
+
+/*
+ * Make sugov_should_update_freq() ignore the rate limit when DL
+ * has increased the utilization.
+ */
+static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
+{
+	if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
+		sg_policy->limits_changed = true;
+}
+
+static void sugov_update_single(struct update_util_data *hook, u64 time,
+				unsigned int flags)
+{
+	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
+	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
+	unsigned long util, max;
+	unsigned int next_f;
+	bool busy;
+
+	sugov_iowait_boost(sg_cpu, time, flags);
+	sg_cpu->last_update = time;
+
+	ignore_dl_rate_limit(sg_cpu, sg_policy);
+
+	if (!sugov_should_update_freq(sg_policy, time))
+		return;
+
+	/* Limits may have changed, don't skip frequency update */
+	busy = !sg_policy->need_freq_update && sugov_cpu_is_busy(sg_cpu);
+
+	util = sugov_get_util(sg_cpu);
+	max = sg_cpu->max;
+	util = sugov_iowait_apply(sg_cpu, time, util, max);
+	next_f = get_next_freq(sg_policy, util, max);
+	/*
+	 * Do not reduce the frequency if the CPU has not been idle
+	 * recently, as the reduction is likely to be premature then.
+	 */
+	if (busy && next_f < sg_policy->next_freq) {
+		next_f = sg_policy->next_freq;
+
+		/* Reset cached freq as next_freq has changed */
+		sg_policy->cached_raw_freq = 0;
+	}
+
+	/*
+	 * This code runs under rq->lock for the target CPU, so it won't run
+	 * concurrently on two different CPUs for the same target and it is not
+	 * necessary to acquire the lock in the fast switch case.
+	 */
+	if (sg_policy->policy->fast_switch_enabled) {
+		sugov_fast_switch(sg_policy, time, next_f);
+	} else {
+		raw_spin_lock(&sg_policy->update_lock);
+		sugov_deferred_update(sg_policy, time, next_f);
+		raw_spin_unlock(&sg_policy->update_lock);
+	}
+}
+
+static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
+{
+	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
+	struct cpufreq_policy *policy = sg_policy->policy;
+	unsigned long util = 0, max = 1;
+	unsigned int j;
+
+	for_each_cpu(j, policy->cpus) {
+		struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
+		unsigned long j_util, j_max;
+
+		j_util = sugov_get_util(j_sg_cpu);
+		j_max = j_sg_cpu->max;
+		j_util = sugov_iowait_apply(j_sg_cpu, time, j_util, j_max);
+
+		if (j_util * max > j_max * util) {
+			util = j_util;
+			max = j_max;
+		}
+	}
+
+	return get_next_freq(sg_policy, util, max);
+}
+
+static void
+sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
+{
+	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
+	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
+	unsigned int next_f;
+
+	raw_spin_lock(&sg_policy->update_lock);
+
+	sugov_iowait_boost(sg_cpu, time, flags);
+	sg_cpu->last_update = time;
+
+	ignore_dl_rate_limit(sg_cpu, sg_policy);
+
+	if (sugov_should_update_freq(sg_policy, time)) {
+		next_f = sugov_next_freq_shared(sg_cpu, time);
+
+		if (sg_policy->policy->fast_switch_enabled)
+			sugov_fast_switch(sg_policy, time, next_f);
+		else
+			sugov_deferred_update(sg_policy, time, next_f);
+	}
+
+	raw_spin_unlock(&sg_policy->update_lock);
+}
+
+static void sugov_work(struct kthread_work *work)
+{
+	struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
+	unsigned int freq;
+	unsigned long flags;
+
+	/*
+	 * Hold sg_policy->update_lock shortly to handle the case where:
+	 * incase sg_policy->next_freq is read here, and then updated by
+	 * sugov_deferred_update() just before work_in_progress is set to false
+	 * here, we may miss queueing the new update.
+	 *
+	 * Note: If a work was queued after the update_lock is released,
+	 * sugov_work() will just be called again by kthread_work code; and the
+	 * request will be proceed before the sugov thread sleeps.
+	 */
+	raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
+	freq = sg_policy->next_freq;
+	sg_policy->work_in_progress = false;
+	raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
+
+	mutex_lock(&sg_policy->work_lock);
+	__cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
+	mutex_unlock(&sg_policy->work_lock);
+}
+
+static void sugov_irq_work(struct irq_work *irq_work)
+{
+	struct sugov_policy *sg_policy;
+
+	sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
+
+	kthread_queue_work(&sg_policy->worker, &sg_policy->work);
+}
+
+/************************** sysfs interface ************************/
+
+static struct sugov_tunables *global_tunables;
+static DEFINE_MUTEX(global_tunables_lock);
+
+static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
+{
+	return container_of(attr_set, struct sugov_tunables, attr_set);
+}
+
+static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
+{
+	struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
+
+	return sprintf(buf, "%u\n", tunables->rate_limit_us);
+}
+
+static ssize_t
+rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
+{
+	struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
+	struct sugov_policy *sg_policy;
+	unsigned int rate_limit_us;
+
+	if (kstrtouint(buf, 10, &rate_limit_us))
+		return -EINVAL;
+
+	tunables->rate_limit_us = rate_limit_us;
+
+	list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
+		sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
+
+	return count;
+}
+
+static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
+
+static struct attribute *sugov_attributes[] = {
+	&rate_limit_us.attr,
+	NULL
+};
+
+static void sugov_tunables_free(struct kobject *kobj)
+{
+	struct gov_attr_set *attr_set = container_of(kobj, struct gov_attr_set, kobj);
+
+	kfree(to_sugov_tunables(attr_set));
+}
+
+static struct kobj_type sugov_tunables_ktype = {
+	.default_attrs = sugov_attributes,
+	.sysfs_ops = &governor_sysfs_ops,
+	.release = &sugov_tunables_free,
+};
+
+/********************** cpufreq governor interface *********************/
+
+static struct cpufreq_governor schedutil_gov;
+
+static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
+{
+	struct sugov_policy *sg_policy;
+
+	sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
+	if (!sg_policy)
+		return NULL;
+
+	sg_policy->policy = policy;
+	raw_spin_lock_init(&sg_policy->update_lock);
+	return sg_policy;
+}
+
+static void sugov_policy_free(struct sugov_policy *sg_policy)
+{
+	kfree(sg_policy);
+}
+
+static int sugov_kthread_create(struct sugov_policy *sg_policy)
+{
+	struct task_struct *thread;
+	struct sched_attr attr = {
+		.size		= sizeof(struct sched_attr),
+		.sched_policy	= SCHED_DEADLINE,
+		.sched_flags	= SCHED_FLAG_SUGOV,
+		.sched_nice	= 0,
+		.sched_priority	= 0,
+		/*
+		 * Fake (unused) bandwidth; workaround to "fix"
+		 * priority inheritance.
+		 */
+		.sched_runtime	=  1000000,
+		.sched_deadline = 10000000,
+		.sched_period	= 10000000,
+	};
+	struct cpufreq_policy *policy = sg_policy->policy;
+	int ret;
+
+	/* kthread only required for slow path */
+	if (policy->fast_switch_enabled)
+		return 0;
+
+	kthread_init_work(&sg_policy->work, sugov_work);
+	kthread_init_worker(&sg_policy->worker);
+	thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
+				"sugov:%d",
+				cpumask_first(policy->related_cpus));
+	if (IS_ERR(thread)) {
+		pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
+		return PTR_ERR(thread);
+	}
+
+	ret = sched_setattr_nocheck(thread, &attr);
+	if (ret) {
+		kthread_stop(thread);
+		pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
+		return ret;
+	}
+
+	sg_policy->thread = thread;
+	kthread_bind_mask(thread, policy->related_cpus);
+	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
+	mutex_init(&sg_policy->work_lock);
+
+	wake_up_process(thread);
+
+	return 0;
+}
+
+static void sugov_kthread_stop(struct sugov_policy *sg_policy)
+{
+	/* kthread only required for slow path */
+	if (sg_policy->policy->fast_switch_enabled)
+		return;
+
+	kthread_flush_worker(&sg_policy->worker);
+	kthread_stop(sg_policy->thread);
+	mutex_destroy(&sg_policy->work_lock);
+}
+
+static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
+{
+	struct sugov_tunables *tunables;
+
+	tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
+	if (tunables) {
+		gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
+		if (!have_governor_per_policy())
+			global_tunables = tunables;
+	}
+	return tunables;
+}
+
+static void sugov_clear_global_tunables(void)
+{
+	if (!have_governor_per_policy())
+		global_tunables = NULL;
+}
+
+static int sugov_init(struct cpufreq_policy *policy)
+{
+	struct sugov_policy *sg_policy;
+	struct sugov_tunables *tunables;
+	int ret = 0;
+
+	/* State should be equivalent to EXIT */
+	if (policy->governor_data)
+		return -EBUSY;
+
+	cpufreq_enable_fast_switch(policy);
+
+	sg_policy = sugov_policy_alloc(policy);
+	if (!sg_policy) {
+		ret = -ENOMEM;
+		goto disable_fast_switch;
+	}
+
+	ret = sugov_kthread_create(sg_policy);
+	if (ret)
+		goto free_sg_policy;
+
+	mutex_lock(&global_tunables_lock);
+
+	if (global_tunables) {
+		if (WARN_ON(have_governor_per_policy())) {
+			ret = -EINVAL;
+			goto stop_kthread;
+		}
+		policy->governor_data = sg_policy;
+		sg_policy->tunables = global_tunables;
+
+		gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
+		goto out;
+	}
+
+	tunables = sugov_tunables_alloc(sg_policy);
+	if (!tunables) {
+		ret = -ENOMEM;
+		goto stop_kthread;
+	}
+
+	tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
+
+	policy->governor_data = sg_policy;
+	sg_policy->tunables = tunables;
+
+	ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
+				   get_governor_parent_kobj(policy), "%s",
+				   schedutil_gov.name);
+	if (ret)
+		goto fail;
+
+out:
+	mutex_unlock(&global_tunables_lock);
+	return 0;
+
+fail:
+	kobject_put(&tunables->attr_set.kobj);
+	policy->governor_data = NULL;
+	sugov_clear_global_tunables();
+
+stop_kthread:
+	sugov_kthread_stop(sg_policy);
+	mutex_unlock(&global_tunables_lock);
+
+free_sg_policy:
+	sugov_policy_free(sg_policy);
+
+disable_fast_switch:
+	cpufreq_disable_fast_switch(policy);
+
+	pr_err("initialization failed (error %d)\n", ret);
+	return ret;
+}
+
+static void sugov_exit(struct cpufreq_policy *policy)
+{
+	struct sugov_policy *sg_policy = policy->governor_data;
+	struct sugov_tunables *tunables = sg_policy->tunables;
+	unsigned int count;
+
+	mutex_lock(&global_tunables_lock);
+
+	count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
+	policy->governor_data = NULL;
+	if (!count)
+		sugov_clear_global_tunables();
+
+	mutex_unlock(&global_tunables_lock);
+
+	sugov_kthread_stop(sg_policy);
+	sugov_policy_free(sg_policy);
+	cpufreq_disable_fast_switch(policy);
+}
+
+static int sugov_start(struct cpufreq_policy *policy)
+{
+	struct sugov_policy *sg_policy = policy->governor_data;
+	unsigned int cpu;
+
+	sg_policy->freq_update_delay_ns	= sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
+	sg_policy->last_freq_update_time	= 0;
+	sg_policy->next_freq			= 0;
+	sg_policy->work_in_progress		= false;
+	sg_policy->limits_changed		= false;
+	sg_policy->need_freq_update		= false;
+	sg_policy->cached_raw_freq		= 0;
+
+	for_each_cpu(cpu, policy->cpus) {
+		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
+
+		memset(sg_cpu, 0, sizeof(*sg_cpu));
+		sg_cpu->cpu			= cpu;
+		sg_cpu->sg_policy		= sg_policy;
+		sg_cpu->min			=
+			(SCHED_CAPACITY_SCALE * policy->cpuinfo.min_freq) /
+			policy->cpuinfo.max_freq;
+	}
+
+	for_each_cpu(cpu, policy->cpus) {
+		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
+
+		cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
+					     policy_is_shared(policy) ?
+							sugov_update_shared :
+							sugov_update_single);
+	}
+	return 0;
+}
+
+static void sugov_stop(struct cpufreq_policy *policy)
+{
+	struct sugov_policy *sg_policy = policy->governor_data;
+	unsigned int cpu;
+
+	for_each_cpu(cpu, policy->cpus)
+		cpufreq_remove_update_util_hook(cpu);
+
+	synchronize_sched();
+
+	if (!policy->fast_switch_enabled) {
+		irq_work_sync(&sg_policy->irq_work);
+		kthread_cancel_work_sync(&sg_policy->work);
+	}
+}
+
+static void sugov_limits(struct cpufreq_policy *policy)
+{
+	struct sugov_policy *sg_policy = policy->governor_data;
+
+	if (!policy->fast_switch_enabled) {
+		mutex_lock(&sg_policy->work_lock);
+		cpufreq_policy_apply_limits(policy);
+		mutex_unlock(&sg_policy->work_lock);
+	}
+
+	sg_policy->limits_changed = true;
+}
+
+static struct cpufreq_governor schedutil_gov = {
+	.name			= "schedutil",
+	.owner			= THIS_MODULE,
+	.dynamic_switching	= true,
+	.init			= sugov_init,
+	.exit			= sugov_exit,
+	.start			= sugov_start,
+	.stop			= sugov_stop,
+	.limits			= sugov_limits,
+};
+
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
+struct cpufreq_governor *cpufreq_default_governor(void)
+{
+	return &schedutil_gov;
+}
+#endif
+
+static int __init sugov_register(void)
+{
+	return cpufreq_register_governor(&schedutil_gov);
+}
+fs_initcall(sugov_register);