cpuquiet: balanced governor

This is a port of the existing governor logic in cpu-tegra3.c.

Change-Id: Id79e6fc697dd0de85242fb2471bbed3d10101693
Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Reviewed-on: http://git-master/r/105271
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Tested-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>

1 files changed, 473 insertions, 0 deletions

diff --git a/drivers/cpuquiet/governors/balanced.c b/drivers/cpuquiet/governors/balanced.c
new file mode 100644
index 000000000000..813a32e671d7
--- /dev/null
+++ b/drivers/cpuquiet/governors/balanced.c
@@ -0,0 +1,473 @@
+/*
+ * Copyright (c) 2012 NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpuquiet.h>
+#include <linux/cpumask.h>
+#include <linux/module.h>
+#include <linux/cpufreq.h>
+#include <linux/pm_qos_params.h>
+#include <linux/jiffies.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/sched.h>
+#include <linux/tick.h>
+#include <asm/cputime.h>
+
+#define CPUNAMELEN 8
+
+typedef enum {
+	CPU_SPEED_BALANCED,
+	CPU_SPEED_BIASED,
+	CPU_SPEED_SKEWED,
+} CPU_SPEED_BALANCE;
+
+typedef enum {
+	IDLE,
+	DOWN,
+	UP,
+} BALANCED_STATE;
+
+struct idle_info {
+	u64 idle_last;
+	u64 last_timestamp;
+	u64 idle_current;
+	u64 timestamp;
+};
+
+static DEFINE_PER_CPU(struct idle_info, idleinfo);
+static DEFINE_PER_CPU(unsigned int, cpu_load);
+
+static struct timer_list load_timer;
+static bool load_timer_active;
+struct balanced_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct balanced_attribute *attr, char *buf);
+	ssize_t (*store)(struct balanced_attribute *attr, const char *buf,
+				size_t count);
+	unsigned long *param;
+};
+
+#define BALANCED_ATTRIBUTE(_name, _mode) \
+	static struct balanced_attribute _name ## _attr = {		\
+		.attr = {.name = __stringify(_name), .mode = _mode },	\
+		.show	= show_attribute,				\
+		.store	= store_attribute,				\
+		.param	= &_name,					\
+}
+
+/* configurable parameters */
+static unsigned long balance_level = 75;
+static unsigned long idle_bottom_freq;
+static unsigned long idle_top_freq;
+static unsigned long up_delay;
+static unsigned long down_delay;
+
+static struct workqueue_struct *balanced_wq;
+static struct delayed_work balanced_work;
+static BALANCED_STATE balanced_state;
+static struct kobject *balanced_kobject;
+
+static void calculate_load_timer(unsigned long data)
+{
+	int i;
+	u64 idle_time, elapsed_time;
+
+	if (!load_timer_active)
+		return;
+
+	for_each_online_cpu(i) {
+		struct idle_info *iinfo = &per_cpu(idleinfo, i);
+		unsigned int *load = &per_cpu(cpu_load, i);
+
+		iinfo->idle_last = iinfo->idle_current;
+		iinfo->last_timestamp = iinfo->timestamp;
+		iinfo->idle_current =
+			get_cpu_idle_time_us(i, &iinfo->timestamp);
+		elapsed_time = iinfo->timestamp - iinfo->last_timestamp;
+
+		idle_time = iinfo->idle_current - iinfo->idle_last;
+		idle_time *= 100;
+		do_div(idle_time, elapsed_time);
+		*load = 100 - idle_time;
+	}
+	mod_timer(&load_timer, jiffies + msecs_to_jiffies(100));
+}
+
+static void start_load_timer(void)
+{
+	int i;
+
+	if (load_timer_active)
+		return;
+
+	load_timer_active = true;
+
+	for_each_online_cpu(i) {
+		struct idle_info *iinfo = &per_cpu(idleinfo, i);
+
+		iinfo->idle_current =
+			get_cpu_idle_time_us(i, &iinfo->timestamp);
+	}
+	mod_timer(&load_timer, jiffies + msecs_to_jiffies(100));
+}
+
+static void stop_load_timer(void)
+{
+	if (!load_timer_active)
+		return;
+
+	load_timer_active = false;
+	del_timer(&load_timer);
+}
+
+static unsigned int get_slowest_cpu_n(void)
+{
+	unsigned int cpu = nr_cpu_ids;
+	unsigned long minload = ULONG_MAX;
+	int i;
+
+	for_each_online_cpu(i) {
+		unsigned int *load = &per_cpu(cpu_load, i);
+
+		if ((i > 0) && (minload > *load)) {
+			cpu = i;
+			minload = *load;
+		}
+	}
+
+	return cpu;
+}
+
+static unsigned int cpu_highest_speed(void)
+{
+	unsigned int maxload = 0;
+	int i;
+
+	for_each_online_cpu(i) {
+		unsigned int *load = &per_cpu(cpu_load, i);
+
+		maxload = max(maxload, *load);
+	}
+
+	return maxload;
+}
+
+static unsigned int count_slow_cpus(unsigned int limit)
+{
+	unsigned int cnt = 0;
+	int i;
+
+	for_each_online_cpu(i) {
+		unsigned int *load = &per_cpu(cpu_load, i);
+
+		if (*load <= limit)
+			cnt++;
+	}
+
+	return cnt;
+}
+
+static CPU_SPEED_BALANCE balanced_speed_balance(void)
+{
+	unsigned long highest_speed = cpu_highest_speed();
+	unsigned long balanced_speed = highest_speed * balance_level / 100;
+	unsigned long skewed_speed = balanced_speed / 2;
+	unsigned int nr_cpus = num_online_cpus();
+	unsigned int max_cpus = pm_qos_request(PM_QOS_MAX_ONLINE_CPUS) ? : 4;
+
+	/* balanced: freq targets for all CPUs are above 50% of highest speed
+	   biased: freq target for at least one CPU is below 50% threshold
+	   skewed: freq targets for at least 2 CPUs are below 25% threshold */
+	if (count_slow_cpus(skewed_speed) >= 2 || nr_cpus > max_cpus)
+		return CPU_SPEED_SKEWED;
+
+	if (count_slow_cpus(balanced_speed) >= 1 || nr_cpus == max_cpus)
+		return CPU_SPEED_BIASED;
+
+	return CPU_SPEED_BALANCED;
+}
+
+static void balanced_work_func(struct work_struct *work)
+{
+	bool up = false;
+	unsigned int cpu = nr_cpu_ids;
+	CPU_SPEED_BALANCE balance;
+
+	switch (balanced_state) {
+	case IDLE:
+		break;
+	case DOWN:
+		cpu = get_slowest_cpu_n();
+		if (cpu < nr_cpu_ids) {
+			up = false;
+			queue_delayed_work(balanced_wq,
+						 &balanced_work, down_delay);
+		} else
+			stop_load_timer();
+		break;
+	case UP:
+		balance = balanced_speed_balance();
+		switch (balance) {
+
+		/* cpu speed is up and balanced - one more on-line */
+		case CPU_SPEED_BALANCED:
+			cpu = cpumask_next_zero(0, cpu_online_mask);
+			if (cpu < nr_cpu_ids)
+				up = true;
+			break;
+		/* cpu speed is up, but skewed - remove one core */
+		case CPU_SPEED_SKEWED:
+			cpu = get_slowest_cpu_n();
+			if (cpu < nr_cpu_ids)
+				up = false;
+			break;
+		/* cpu speed is up, but under-utilized - do nothing */
+		case CPU_SPEED_BIASED:
+		default:
+			break;
+		}
+		queue_delayed_work(
+			balanced_wq, &balanced_work, up_delay);
+		break;
+	default:
+		pr_err("%s: invalid cpuquiet balanced governor state %d\n",
+		       __func__, balanced_state);
+	}
+
+	if (cpu < nr_cpu_ids) {
+		if (up)
+			cpuquiet_wake_cpu(cpu);
+		else
+			cpuquiet_quiesence_cpu(cpu);
+	}
+}
+
+static int balanced_cpufreq_transition(struct notifier_block *nb,
+	unsigned long state, void *data)
+{
+	struct cpufreq_freqs *freqs = data;
+	unsigned long cpu_freq;
+
+	if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE) {
+		cpu_freq = freqs->new;
+
+		switch (balanced_state) {
+		case IDLE:
+			if (cpu_freq > idle_top_freq) {
+				balanced_state = UP;
+				queue_delayed_work(
+					balanced_wq, &balanced_work, up_delay);
+				start_load_timer();
+			} else if (cpu_freq <= idle_bottom_freq) {
+				balanced_state = DOWN;
+				queue_delayed_work(
+					balanced_wq, &balanced_work,
+					down_delay);
+				start_load_timer();
+			}
+			break;
+		case DOWN:
+			if (cpu_freq > idle_top_freq) {
+				balanced_state = UP;
+				queue_delayed_work(
+					balanced_wq, &balanced_work, up_delay);
+				start_load_timer();
+			}
+			break;
+		case UP:
+			if (cpu_freq <= idle_bottom_freq) {
+				balanced_state = DOWN;
+				queue_delayed_work(balanced_wq,
+					&balanced_work, down_delay);
+				start_load_timer();
+			}
+			break;
+		default:
+			pr_err("%s: invalid tegra hotplug state %d\n",
+				__func__, balanced_state);
+		}
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block balanced_cpufreq_nb = {
+	.notifier_call = balanced_cpufreq_transition,
+};
+
+static ssize_t show_attribute(struct balanced_attribute *battr, char *buf)
+{
+	return sprintf(buf, "%lu\n", *(battr->param));
+}
+
+static ssize_t store_attribute(struct balanced_attribute *battr,
+					const char *buf, size_t count)
+{
+	int err;
+	unsigned long val;
+
+	err = strict_strtoul(buf, 0, &val);
+	if (err < 0)
+		return err;
+
+	*(battr->param) = val;
+
+	return count;
+}
+
+static ssize_t balanced_sysfs_store(struct kobject *kobj,
+			struct attribute *attr, const char *buf, size_t count)
+{
+	struct balanced_attribute *battr =
+		 container_of(attr, struct balanced_attribute, attr);
+
+	if (battr->store)
+		return battr->store(battr, buf, count);
+
+	return -EINVAL;
+}
+
+static ssize_t balanced_sysfs_show(struct kobject *kobj,
+			struct attribute *attr, char *buf)
+{
+	struct balanced_attribute *battr =
+		 container_of(attr, struct balanced_attribute, attr);
+
+	return battr->show(battr, buf);
+}
+
+BALANCED_ATTRIBUTE(balance_level, 0644);
+BALANCED_ATTRIBUTE(idle_bottom_freq, 0644);
+BALANCED_ATTRIBUTE(idle_top_freq, 0644);
+BALANCED_ATTRIBUTE(up_delay, 0644);
+BALANCED_ATTRIBUTE(down_delay, 0644);
+
+static struct attribute *balanced_attributes[] = {
+	&balance_level_attr.attr,
+	&idle_bottom_freq_attr.attr,
+	&idle_top_freq_attr.attr,
+	&up_delay_attr.attr,
+	&down_delay_attr.attr,
+	NULL,
+};
+
+static const struct sysfs_ops balanced_sysfs_ops = {
+	.show = balanced_sysfs_show,
+	.store = balanced_sysfs_store,
+};
+
+static struct kobj_type ktype_balanced = {
+	.sysfs_ops = &balanced_sysfs_ops,
+	.default_attrs = balanced_attributes,
+};
+
+static int balanced_sysfs(void)
+{
+	int err;
+
+	balanced_kobject = kzalloc(sizeof(*balanced_kobject),
+				GFP_KERNEL);
+
+	if (!balanced_kobject)
+		return -ENOMEM;
+
+	err = cpuquiet_kobject_init(balanced_kobject, &ktype_balanced,
+				"balanced");
+
+	if (err)
+		kfree(balanced_kobject);
+
+	return err;
+}
+
+static void balanced_stop(void)
+{
+
+	/*
+	   first unregister the notifiers. This ensures the governor state
+	   can't be modified by a cpufreq transition
+	*/
+	cpufreq_unregister_notifier(&balanced_cpufreq_nb,
+		CPUFREQ_TRANSITION_NOTIFIER);
+
+	/* now we can force the governor to be idle */
+	balanced_state = IDLE;
+	cancel_delayed_work_sync(&balanced_work);
+	destroy_workqueue(balanced_wq);
+	del_timer(&load_timer);
+
+	kobject_put(balanced_kobject);
+}
+
+static int balanced_start(void)
+{
+	int err, count;
+	struct cpufreq_frequency_table *table;
+
+	err = balanced_sysfs();
+	if (err)
+		return err;
+
+	balanced_wq = alloc_workqueue("cpuquiet-balanced",
+			WQ_UNBOUND | WQ_RESCUER | WQ_FREEZABLE, 1);
+	if (!balanced_wq)
+		return -ENOMEM;
+
+	INIT_DELAYED_WORK(&balanced_work, balanced_work_func);
+
+	up_delay = msecs_to_jiffies(1000);
+	down_delay = msecs_to_jiffies(2000);
+
+	table = cpufreq_frequency_get_table(0);
+	for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
+		;
+
+	idle_top_freq = table[(count / 2) - 1].frequency;
+	idle_bottom_freq = table[(count / 2) - 2].frequency;
+
+	cpufreq_register_notifier(&balanced_cpufreq_nb,
+		CPUFREQ_TRANSITION_NOTIFIER);
+
+	init_timer(&load_timer);
+	load_timer.function = calculate_load_timer;
+
+	return 0;
+}
+
+struct cpuquiet_governor balanced_governor = {
+	.name		= "balanced",
+	.start		= balanced_start,
+	.stop		= balanced_stop,
+	.owner		= THIS_MODULE,
+};
+
+static int __init init_balanced(void)
+{
+	return cpuquiet_register_governor(&balanced_governor);
+}
+
+static void __exit exit_balanced(void)
+{
+	cpuquiet_unregister_governor(&balanced_governor);
+}
+
+MODULE_LICENSE("GPL");
+module_init(init_balanced);
+module_exit(exit_balanced);
+