tongson/gist:1172524

## gistfile1.diff
diff linux/Documentation/cpu-freq/governors.txt linux/Documentation/cpu-freq/governors.txt
--- linux/Documentation/cpu-freq/governors.txt
+++ linux/Documentation/cpu-freq/governors.txt
@@ -28,6 +28,7 @@ Contents:
 2.3  Userspace
 2.4  Ondemand
 2.5  Conservative
+2.6  Interactive

 3.   The Governor Interface in the CPUfreq Core

@@ -193,6 +194,43 @@ governor but for the opposite direction.
 default value of '20' it means that if the CPU usage needs to be below
 20% between samples to have the frequency decreased.

+
+2.6 Interactive
+---------------
+
+The CPUfreq governor "interactive" is designed for latency-sensitive,
+interactive workloads. This governor sets the CPU speed depending on
+usage, similar to "ondemand" and "conservative" governors.  However,
+the governor is more aggressive about scaling the CPU speed up in
+response to CPU-intensive activity.
+
+Sampling the CPU load every X ms can lead to under-powering the CPU
+for X ms, leading to dropped frames, stuttering UI, etc.  Instead of
+sampling the cpu at a specified rate, the interactive governor will
+check whether to scale the cpu frequency up soon after coming out of
+idle.  When the cpu comes out of idle, a timer is configured to fire
+within 1-2 ticks.  If the cpu is very busy between exiting idle and
+when the timer fires then we assume the cpu is underpowered and ramp
+to MAX speed.
+
+If the cpu was not sufficiently busy to immediately ramp to MAX speed,
+then governor evaluates the cpu load since the last speed adjustment,
+choosing the highest value between that longer-term load or the
+short-term load since idle exit to determine the cpu speed to ramp to.
+
+The tuneable values for this governor are:
+
+min_sample_time: The minimum amount of time to spend at the current
+frequency before ramping down. This is to ensure that the governor has
+seen enough historic cpu load data to determine the appropriate
+workload.  Default is 80000 uS.
+
+go_maxspeed_load: The CPU load at which to ramp to max speed.  Default
+is 85.
+
+timer_rate: Sample rate for reevaluating cpu load when the system is
+not idle.  Default is 30000 uS.
+
 3. The Governor Interface in the CPUfreq Core
 =============================================

diff linux/drivers/cpufreq/Kconfig linux/drivers/cpufreq/Kconfig
--- linux/drivers/cpufreq/Kconfig
+++ linux/drivers/cpufreq/Kconfig
@@ -99,6 +99,16 @@ config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 	  Be aware that not all cpufreq drivers support the conservative
 	  governor. If unsure have a look at the help section of the
 	  driver. Fallback governor will be the performance governor.
+
+config CPU_FREQ_DEFAULT_GOV_INTERACTIVE
+	bool "interactive"
+	select CPU_FREQ_GOV_INTERACTIVE
+	help
+	  Use the CPUFreq governor 'interactive' as default. This allows
+	  you to get a full dynamic cpu frequency capable system by simply
+	  loading your cpufreq low-level hardware driver, using the
+	  'interactive' governor for latency-sensitive workloads.
+
 endchoice

 config CPU_FREQ_GOV_PERFORMANCE
@@ -154,6 +164,23 @@ config CPU_FREQ_GOV_ONDEMAND

 	  For details, take a look at linux/Documentation/cpu-freq.

+	  If in doubt, say N.
+
+config CPU_FREQ_GOV_INTERACTIVE
+	tristate "'interactive' cpufreq policy governor"
+	help
+	  'interactive' - This driver adds a dynamic cpufreq policy governor
+	  designed for latency-sensitive workloads.
+
+	  This governor attempts to reduce the latency of clock
+	  increases so that the system is more responsive to
+	  interactive workloads.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called cpufreq_interactive.
+
+	  For details, take a look at linux/Documentation/cpu-freq.
+
 	  If in doubt, say N.

 config CPU_FREQ_GOV_CONSERVATIVE
diff linux/drivers/cpufreq/Makefile linux/drivers/cpufreq/Makefile
--- linux/drivers/cpufreq/Makefile
+++ linux/drivers/cpufreq/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_CPU_FREQ_GOV_POWERSAVE)	+=
 obj-$(CONFIG_CPU_FREQ_GOV_USERSPACE)	+= cpufreq_userspace.o
 obj-$(CONFIG_CPU_FREQ_GOV_ONDEMAND)	+= cpufreq_ondemand.o
 obj-$(CONFIG_CPU_FREQ_GOV_CONSERVATIVE)	+= cpufreq_conservative.o
+obj-$(CONFIG_CPU_FREQ_GOV_INTERACTIVE)	+= cpufreq_interactive.o

 # CPUfreq cross-arch helpers
 obj-$(CONFIG_CPU_FREQ_TABLE)		+= freq_table.o
diff linux/drivers/cpufreq/cpufreq_interactive.c linux/drivers/cpufreq/cpufreq_interactive.c
--- linux/drivers/cpufreq/cpufreq_interactive.c
+++ linux/drivers/cpufreq/cpufreq_interactive.c
@@ -0,0 +1,640 @@
+/*
+ * drivers/cpufreq/cpufreq_interactive.c
+ *
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Author: Mike Chan (mike@android.com)
+ *
+ */
+
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/cpufreq.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/tick.h>
+#include <linux/timer.h>
+#include <linux/workqueue.h>
+#include <linux/kthread.h>
+
+#include <asm/cputime.h>
+
+static atomic_t active_count = ATOMIC_INIT(0);
+
+struct cpufreq_interactive_cpuinfo {
+	struct timer_list cpu_timer;
+	int timer_idlecancel;
+	u64 time_in_idle;
+	u64 idle_exit_time;
+	u64 timer_run_time;
+	int idling;
+	u64 freq_change_time;
+	u64 freq_change_time_in_idle;
+	struct cpufreq_policy *policy;
+	struct cpufreq_frequency_table *freq_table;
+	unsigned int target_freq;
+	int governor_enabled;
+};
+
+static DEFINE_PER_CPU(struct cpufreq_interactive_cpuinfo, cpuinfo);
+
+/* Workqueues handle frequency scaling */
+static struct task_struct *up_task;
+static struct workqueue_struct *down_wq;
+static struct work_struct freq_scale_down_work;
+static cpumask_t up_cpumask;
+static spinlock_t up_cpumask_lock;
+static cpumask_t down_cpumask;
+static spinlock_t down_cpumask_lock;
+
+/* Go to max speed when CPU load at or above this value. */
+#define DEFAULT_GO_MAXSPEED_LOAD 85
+static unsigned long go_maxspeed_load;
+
+/*
+ * The minimum amount of time to spend at a frequency before we can ramp down.
+ */
+#define DEFAULT_MIN_SAMPLE_TIME 80000;
+static unsigned long min_sample_time;
+
+/*
+ * The sample rate of the timer used to increase frequency
+ */
+#define DEFAULT_TIMER_RATE 30000;
+static unsigned long timer_rate;
+
+static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
+		unsigned int event);
+
+#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_INTERACTIVE
+static
+#endif
+struct cpufreq_governor cpufreq_gov_interactive = {
+	.name = "interactive",
+	.governor = cpufreq_governor_interactive,
+	.max_transition_latency = 10000000,
+	.owner = THIS_MODULE,
+};
+
+static void cpufreq_interactive_timer(unsigned long data)
+{
+	unsigned int delta_idle;
+	unsigned int delta_time;
+	int cpu_load;
+	int load_since_change;
+	u64 time_in_idle;
+	u64 idle_exit_time;
+	struct cpufreq_interactive_cpuinfo *pcpu =
+		&per_cpu(cpuinfo, data);
+	u64 now_idle;
+	unsigned int new_freq;
+	unsigned int index;
+	unsigned long flags;
+
+	smp_rmb();
+
+	if (!pcpu->governor_enabled)
+		goto exit;
+
+	/*
+	 * Once pcpu->timer_run_time is updated to >= pcpu->idle_exit_time,
+	 * this lets idle exit know the current idle time sample has
+	 * been processed, and idle exit can generate a new sample and
+	 * re-arm the timer.  This prevents a concurrent idle
+	 * exit on that CPU from writing a new set of info at the same time
+	 * the timer function runs (the timer function can't use that info
+	 * until more time passes).
+	 */
+	time_in_idle = pcpu->time_in_idle;
+	idle_exit_time = pcpu->idle_exit_time;
+	now_idle = get_cpu_idle_time_us(data, &pcpu->timer_run_time);
+	smp_wmb();
+
+	/* If we raced with cancelling a timer, skip. */
+	if (!idle_exit_time)
+		goto exit;
+
+	delta_idle = (unsigned int) cputime64_sub(now_idle, time_in_idle);
+	delta_time = (unsigned int) cputime64_sub(pcpu->timer_run_time,
+						  idle_exit_time);
+
+	/*
+	 * If timer ran less than 1ms after short-term sample started, retry.
+	 */
+	if (delta_time < 1000)
+		goto rearm;
+
+	if (delta_idle > delta_time)
+		cpu_load = 0;
+	else
+		cpu_load = 100 * (delta_time - delta_idle) / delta_time;
+
+	delta_idle = (unsigned int) cputime64_sub(now_idle,
+						pcpu->freq_change_time_in_idle);
+	delta_time = (unsigned int) cputime64_sub(pcpu->timer_run_time,
+						  pcpu->freq_change_time);
+
+	if (delta_idle > delta_time)
+		load_since_change = 0;
+	else
+		load_since_change =
+			100 * (delta_time - delta_idle) / delta_time;
+
+	/*
+	 * Choose greater of short-term load (since last idle timer
+	 * started or timer function re-armed itself) or long-term load
+	 * (since last frequency change).
+	 */
+	if (load_since_change > cpu_load)
+		cpu_load = load_since_change;
+
+	if (cpu_load >= go_maxspeed_load)
+		new_freq = pcpu->policy->max;
+	else
+		new_freq = pcpu->policy->max * cpu_load / 100;
+
+	if (cpufreq_frequency_table_target(pcpu->policy, pcpu->freq_table,
+					   new_freq, CPUFREQ_RELATION_H,
+					   &index)) {
+		pr_warn_once("timer %d: cpufreq_frequency_table_target error\n",
+			     (int) data);
+		goto rearm;
+	}
+
+	new_freq = pcpu->freq_table[index].frequency;
+
+	if (pcpu->target_freq == new_freq)
+		goto rearm_if_notmax;
+
+	/*
+	 * Do not scale down unless we have been at this frequency for the
+	 * minimum sample time.
+	 */
+	if (new_freq < pcpu->target_freq) {
+		if (cputime64_sub(pcpu->timer_run_time, pcpu->freq_change_time)
+		    < min_sample_time)
+			goto rearm;
+	}
+
+	if (new_freq < pcpu->target_freq) {
+		pcpu->target_freq = new_freq;
+		spin_lock_irqsave(&down_cpumask_lock, flags);
+		cpumask_set_cpu(data, &down_cpumask);
+		spin_unlock_irqrestore(&down_cpumask_lock, flags);
+		queue_work(down_wq, &freq_scale_down_work);
+	} else {
+		pcpu->target_freq = new_freq;
+		spin_lock_irqsave(&up_cpumask_lock, flags);
+		cpumask_set_cpu(data, &up_cpumask);
+		spin_unlock_irqrestore(&up_cpumask_lock, flags);
+		wake_up_process(up_task);
+	}
+
+rearm_if_notmax:
+	/*
+	 * Already set max speed and don't see a need to change that,
+	 * wait until next idle to re-evaluate, don't need timer.
+	 */
+	if (pcpu->target_freq == pcpu->policy->max)
+		goto exit;
+
+rearm:
+	if (!timer_pending(&pcpu->cpu_timer)) {
+		/*
+		 * If already at min: if that CPU is idle, don't set timer.
+		 * Else cancel the timer if that CPU goes idle.  We don't
+		 * need to re-evaluate speed until the next idle exit.
+		 */
+		if (pcpu->target_freq == pcpu->policy->min) {
+			smp_rmb();
+
+			if (pcpu->idling)
+				goto exit;
+
+			pcpu->timer_idlecancel = 1;
+		}
+
+		pcpu->time_in_idle = get_cpu_idle_time_us(
+			data, &pcpu->idle_exit_time);
+		mod_timer(&pcpu->cpu_timer,
+			  jiffies + usecs_to_jiffies(timer_rate));
+	}
+
+exit:
+	return;
+}
+
+static void cpufreq_interactive_idle_start(void)
+{
+	struct cpufreq_interactive_cpuinfo *pcpu =
+		&per_cpu(cpuinfo, smp_processor_id());
+	int pending;
+
+	if (!pcpu->governor_enabled)
+		return;
+
+	pcpu->idling = 1;
+	smp_wmb();
+	pending = timer_pending(&pcpu->cpu_timer);
+
+	if (pcpu->target_freq != pcpu->policy->min) {
+#ifdef CONFIG_SMP
+		/*
+		 * Entering idle while not at lowest speed.  On some
+		 * platforms this can hold the other CPU(s) at that speed
+		 * even though the CPU is idle. Set a timer to re-evaluate
+		 * speed so this idle CPU doesn't hold the other CPUs above
+		 * min indefinitely.  This should probably be a quirk of
+		 * the CPUFreq driver.
+		 */
+		if (!pending) {
+			pcpu->time_in_idle = get_cpu_idle_time_us(
+				smp_processor_id(), &pcpu->idle_exit_time);
+			pcpu->timer_idlecancel = 0;
+			mod_timer(&pcpu->cpu_timer,
+				  jiffies + usecs_to_jiffies(timer_rate));
+		}
+#endif
+	} else {
+		/*
+		 * If at min speed and entering idle after load has
+		 * already been evaluated, and a timer has been set just in
+		 * case the CPU suddenly goes busy, cancel that timer.  The
+		 * CPU didn't go busy; we'll recheck things upon idle exit.
+		 */
+		if (pending && pcpu->timer_idlecancel) {
+			del_timer(&pcpu->cpu_timer);
+			/*
+			 * Ensure last timer run time is after current idle
+			 * sample start time, so next idle exit will always
+			 * start a new idle sampling period.
+			 */
+			pcpu->idle_exit_time = 0;
+			pcpu->timer_idlecancel = 0;
+		}
+	}
+
+}
+
+static void cpufreq_interactive_idle_end(void)
+{
+	struct cpufreq_interactive_cpuinfo *pcpu =
+		&per_cpu(cpuinfo, smp_processor_id());
+
+	pcpu->idling = 0;
+	smp_wmb();
+
+	/*
+	 * Arm the timer for 1-2 ticks later if not already, and if the timer
+	 * function has already processed the previous load sampling
+	 * interval.  (If the timer is not pending but has not processed
+	 * the previous interval, it is probably racing with us on another
+	 * CPU.  Let it compute load based on the previous sample and then
+	 * re-arm the timer for another interval when it's done, rather
+	 * than updating the interval start time to be "now", which doesn't
+	 * give the timer function enough time to make a decision on this
+	 * run.)
+	 */
+	if (timer_pending(&pcpu->cpu_timer) == 0 &&
+	    pcpu->timer_run_time >= pcpu->idle_exit_time &&
+	    pcpu->governor_enabled) {
+		pcpu->time_in_idle =
+			get_cpu_idle_time_us(smp_processor_id(),
+					     &pcpu->idle_exit_time);
+		pcpu->timer_idlecancel = 0;
+		mod_timer(&pcpu->cpu_timer,
+			  jiffies + usecs_to_jiffies(timer_rate));
+	}
+
+}
+
+static int cpufreq_interactive_up_task(void *data)
+{
+	unsigned int cpu;
+	cpumask_t tmp_mask;
+	unsigned long flags;
+	struct cpufreq_interactive_cpuinfo *pcpu;
+
+	while (1) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		spin_lock_irqsave(&up_cpumask_lock, flags);
+
+		if (cpumask_empty(&up_cpumask)) {
+			spin_unlock_irqrestore(&up_cpumask_lock, flags);
+			schedule();
+
+			if (kthread_should_stop())
+				break;
+
+			spin_lock_irqsave(&up_cpumask_lock, flags);
+		}
+
+		set_current_state(TASK_RUNNING);
+
+		tmp_mask = up_cpumask;
+		cpumask_clear(&up_cpumask);
+		spin_unlock_irqrestore(&up_cpumask_lock, flags);
+
+		for_each_cpu(cpu, &tmp_mask) {
+			pcpu = &per_cpu(cpuinfo, cpu);
+
+			smp_rmb();
+
+			if (!pcpu->governor_enabled)
+				continue;
+
+			__cpufreq_driver_target(pcpu->policy,
+						pcpu->target_freq,
+						CPUFREQ_RELATION_H);
+			pcpu->freq_change_time_in_idle =
+				get_cpu_idle_time_us(cpu,
+						     &pcpu->freq_change_time);
+		}
+	}
+
+	return 0;
+}
+
+static void cpufreq_interactive_freq_down(struct work_struct *work)
+{
+	unsigned int cpu;
+	cpumask_t tmp_mask;
+	unsigned long flags;
+	struct cpufreq_interactive_cpuinfo *pcpu;
+
+	spin_lock_irqsave(&down_cpumask_lock, flags);
+	tmp_mask = down_cpumask;
+	cpumask_clear(&down_cpumask);
+	spin_unlock_irqrestore(&down_cpumask_lock, flags);
+
+	for_each_cpu(cpu, &tmp_mask) {
+		pcpu = &per_cpu(cpuinfo, cpu);
+
+		smp_rmb();
+
+		if (!pcpu->governor_enabled)
+			continue;
+
+		__cpufreq_driver_target(pcpu->policy,
+					pcpu->target_freq,
+					CPUFREQ_RELATION_H);
+		pcpu->freq_change_time_in_idle =
+			get_cpu_idle_time_us(cpu,
+					     &pcpu->freq_change_time);
+	}
+}
+
+static ssize_t show_go_maxspeed_load(struct kobject *kobj,
+				     struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", go_maxspeed_load);
+}
+
+static ssize_t store_go_maxspeed_load(struct kobject *kobj,
+			struct attribute *attr, const char *buf, size_t count)
+{
+	int ret;
+	unsigned long val;
+
+	ret = strict_strtoul(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+	go_maxspeed_load = val;
+	return count;
+}
+
+static struct global_attr go_maxspeed_load_attr = __ATTR(go_maxspeed_load, 0644,
+		show_go_maxspeed_load, store_go_maxspeed_load);
+
+static ssize_t show_min_sample_time(struct kobject *kobj,
+				struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", min_sample_time);
+}
+
+static ssize_t store_min_sample_time(struct kobject *kobj,
+			struct attribute *attr, const char *buf, size_t count)
+{
+	int ret;
+	unsigned long val;
+
+	ret = strict_strtoul(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+	min_sample_time = val;
+	return count;
+}
+
+static struct global_attr min_sample_time_attr = __ATTR(min_sample_time, 0644,
+		show_min_sample_time, store_min_sample_time);
+
+static ssize_t show_timer_rate(struct kobject *kobj,
+			struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", timer_rate);
+}
+
+static ssize_t store_timer_rate(struct kobject *kobj,
+			struct attribute *attr, const char *buf, size_t count)
+{
+	int ret;
+	unsigned long val;
+
+	ret = strict_strtoul(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+	timer_rate = val;
+	return count;
+}
+
+static struct global_attr timer_rate_attr = __ATTR(timer_rate, 0644,
+		show_timer_rate, store_timer_rate);
+
+static struct attribute *interactive_attributes[] = {
+	&go_maxspeed_load_attr.attr,
+	&min_sample_time_attr.attr,
+	&timer_rate_attr.attr,
+	NULL,
+};
+
+static struct attribute_group interactive_attr_group = {
+	.attrs = interactive_attributes,
+	.name = "interactive",
+};
+
+static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
+		unsigned int event)
+{
+	int rc;
+	unsigned int j;
+	struct cpufreq_interactive_cpuinfo *pcpu;
+	struct cpufreq_frequency_table *freq_table;
+
+	switch (event) {
+	case CPUFREQ_GOV_START:
+		if (!cpu_online(policy->cpu))
+			return -EINVAL;
+
+		freq_table =
+			cpufreq_frequency_get_table(policy->cpu);
+
+		for_each_cpu(j, policy->cpus) {
+			pcpu = &per_cpu(cpuinfo, j);
+			pcpu->policy = policy;
+			pcpu->target_freq = policy->cur;
+			pcpu->freq_table = freq_table;
+			pcpu->freq_change_time_in_idle =
+				get_cpu_idle_time_us(j,
+					     &pcpu->freq_change_time);
+			pcpu->governor_enabled = 1;
+			smp_wmb();
+		}
+
+		/*
+		 * Do not register the idle hook and create sysfs
+		 * entries if we have already done so.
+		 */
+		if (atomic_inc_return(&active_count) > 1)
+			return 0;
+
+		rc = sysfs_create_group(cpufreq_global_kobject,
+				&interactive_attr_group);
+		if (rc)
+			return rc;
+
+		break;
+
+	case CPUFREQ_GOV_STOP:
+		for_each_cpu(j, policy->cpus) {
+			pcpu = &per_cpu(cpuinfo, j);
+			pcpu->governor_enabled = 0;
+			smp_wmb();
+			del_timer_sync(&pcpu->cpu_timer);
+
+			/*
+			 * Reset idle exit time since we may cancel the timer
+			 * before it can run after the last idle exit time,
+			 * to avoid tripping the check in idle exit for a timer
+			 * that is trying to run.
+			 */
+			pcpu->idle_exit_time = 0;
+		}
+
+		flush_work(&freq_scale_down_work);
+		if (atomic_dec_return(&active_count) > 0)
+			return 0;
+
+		sysfs_remove_group(cpufreq_global_kobject,
+				&interactive_attr_group);
+
+		break;
+
+	case CPUFREQ_GOV_LIMITS:
+		if (policy->max < policy->cur)
+			__cpufreq_driver_target(policy,
+					policy->max, CPUFREQ_RELATION_H);
+		else if (policy->min > policy->cur)
+			__cpufreq_driver_target(policy,
+					policy->min, CPUFREQ_RELATION_L);
+		break;
+	}
+	return 0;
+}
+
+static int cpufreq_interactive_idle_notifier(struct notifier_block *nb,
+					     unsigned long val,
+					     void *data)
+{
+	switch (val) {
+	case IDLE_START:
+		cpufreq_interactive_idle_start();
+		break;
+	case IDLE_END:
+		cpufreq_interactive_idle_end();
+		break;
+	}
+
+	return 0;
+}
+
+static struct notifier_block cpufreq_interactive_idle_nb = {
+	.notifier_call = cpufreq_interactive_idle_notifier,
+};
+
+static int __init cpufreq_interactive_init(void)
+{
+	unsigned int i;
+	struct cpufreq_interactive_cpuinfo *pcpu;
+	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+
+	go_maxspeed_load = DEFAULT_GO_MAXSPEED_LOAD;
+	min_sample_time = DEFAULT_MIN_SAMPLE_TIME;
+	timer_rate = DEFAULT_TIMER_RATE;
+
+	/* Initalize per-cpu timers */
+	for_each_possible_cpu(i) {
+		pcpu = &per_cpu(cpuinfo, i);
+		init_timer(&pcpu->cpu_timer);
+		pcpu->cpu_timer.function = cpufreq_interactive_timer;
+		pcpu->cpu_timer.data = i;
+	}
+
+	up_task = kthread_create(cpufreq_interactive_up_task, NULL,
+				 "kinteractiveup");
+	if (IS_ERR(up_task))
+		return PTR_ERR(up_task);
+
+	sched_setscheduler_nocheck(up_task, SCHED_FIFO, &param);
+	get_task_struct(up_task);
+
+	/* No rescuer thread, bind to CPU queuing the work for possibly
+	   warm cache (probably doesn't matter much). */
+	down_wq = alloc_workqueue("knteractive_down", 0, 1);
+
+	if (!down_wq)
+		goto err_freeuptask;
+
+	INIT_WORK(&freq_scale_down_work,
+		  cpufreq_interactive_freq_down);
+
+	spin_lock_init(&up_cpumask_lock);
+	spin_lock_init(&down_cpumask_lock);
+
+	idle_notifier_register(&cpufreq_interactive_idle_nb);
+
+	return cpufreq_register_governor(&cpufreq_gov_interactive);
+
+err_freeuptask:
+	put_task_struct(up_task);
+	return -ENOMEM;
+}
+
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_INTERACTIVE
+fs_initcall(cpufreq_interactive_init);
+#else
+module_init(cpufreq_interactive_init);
+#endif
+
+static void __exit cpufreq_interactive_exit(void)
+{
+	cpufreq_unregister_governor(&cpufreq_gov_interactive);
+	kthread_stop(up_task);
+	put_task_struct(up_task);
+	destroy_workqueue(down_wq);
+}
+
+module_exit(cpufreq_interactive_exit);
+
+MODULE_AUTHOR("Mike Chan <mike@android.com>");
+MODULE_DESCRIPTION("'cpufreq_interactive' - A cpufreq governor for "
+	"Latency sensitive workloads");
+MODULE_LICENSE("GPL");
diff linux/include/linux/cpufreq.h linux/include/linux/cpufreq.h
--- linux/include/linux/cpufreq.h
+++ linux/include/linux/cpufreq.h
@@ -358,6 +358,9 @@ extern struct cpufreq_governor cpufreq_g
 #elif defined(CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE)
 extern struct cpufreq_governor cpufreq_gov_conservative;
 #define CPUFREQ_DEFAULT_GOVERNOR	(&cpufreq_gov_conservative)
+#elif defined(CONFIG_CPU_FREQ_DEFAULT_GOV_INTERACTIVE)
+extern struct cpufreq_governor cpufreq_gov_interactive;
+#define CPUFREQ_DEFAULT_GOVERNOR	(&cpufreq_gov_interactive)
 #endif


diff linux/arch/x86/include/asm/idle.h linux/arch/x86/include/asm/idle.h
--- linux/arch/x86/include/asm/idle.h
+++ linux/arch/x86/include/asm/idle.h
@@ -1,13 +1,6 @@
 #ifndef _ASM_X86_IDLE_H
 #define _ASM_X86_IDLE_H

-#define IDLE_START 1
-#define IDLE_END 2
-
-struct notifier_block;
-void idle_notifier_register(struct notifier_block *n);
-void idle_notifier_unregister(struct notifier_block *n);
-
 #ifdef CONFIG_X86_64
 void enter_idle(void);
 void exit_idle(void);
diff linux/arch/x86/kernel/process_64.c linux/arch/x86/kernel/process_64.c
--- linux/arch/x86/kernel/process_64.c
+++ linux/arch/x86/kernel/process_64.c
@@ -56,31 +56,17 @@ asmlinkage extern void ret_from_fork(voi
 DEFINE_PER_CPU(unsigned long, old_rsp);
 static DEFINE_PER_CPU(unsigned char, is_idle);

-static ATOMIC_NOTIFIER_HEAD(idle_notifier);
-
-void idle_notifier_register(struct notifier_block *n)
-{
-	atomic_notifier_chain_register(&idle_notifier, n);
-}
-EXPORT_SYMBOL_GPL(idle_notifier_register);
-
-void idle_notifier_unregister(struct notifier_block *n)
-{
-	atomic_notifier_chain_unregister(&idle_notifier, n);
-}
-EXPORT_SYMBOL_GPL(idle_notifier_unregister);
-
 void enter_idle(void)
 {
 	percpu_write(is_idle, 1);
-	atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
+	idle_notifier_call_chain(IDLE_START);
 }

 static void __exit_idle(void)
 {
 	if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
 		return;
-	atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
+	idle_notifier_call_chain(IDLE_END);
 }

 /* Called from interrupts to signify idle end */
diff linux/include/linux/cpu.h linux/include/linux/cpu.h
--- linux/include/linux/cpu.h
+++ linux/include/linux/cpu.h
@@ -174,4 +174,11 @@ static inline int disable_nonboot_cpus(v
 static inline void enable_nonboot_cpus(void) {}
 #endif /* !CONFIG_PM_SLEEP_SMP */

+#define IDLE_START 1
+#define IDLE_END 2
+
+void idle_notifier_register(struct notifier_block *n);
+void idle_notifier_unregister(struct notifier_block *n);
+void idle_notifier_call_chain(unsigned long val);
+
 #endif /* _LINUX_CPU_H_ */
diff linux/kernel/cpu.c linux/kernel/cpu.c
--- linux/kernel/cpu.c
+++ linux/kernel/cpu.c
@@ -594,3 +594,23 @@ void init_cpu_online(const struct cpumas
 {
 	cpumask_copy(to_cpumask(cpu_online_bits), src);
 }
+
+static ATOMIC_NOTIFIER_HEAD(idle_notifier);
+
+void idle_notifier_register(struct notifier_block *n)
+{
+	atomic_notifier_chain_register(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_register);
+
+void idle_notifier_unregister(struct notifier_block *n)
+{
+	atomic_notifier_chain_unregister(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_unregister);
+
+void idle_notifier_call_chain(unsigned long val)
+{
+	atomic_notifier_call_chain(&idle_notifier, val, NULL);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_call_chain);