--- /dev/null
+/*
+ * drivers/cpufreq/cpufreq_conservative.c
+ *
+ * Copyright (C) 2001 Russell King
+ * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
+ * Jun Nakajima <jun.nakajima@intel.com>
+ * (C) 2004 Alexander Clouter <alex-kernel@digriz.org.uk>
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/ctype.h>
+#include <linux/cpufreq.h>
+#include <linux/sysctl.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/sysfs.h>
+#include <linux/sched.h>
+#include <linux/kmod.h>
+#include <linux/workqueue.h>
+#include <linux/jiffies.h>
+#include <linux/kernel_stat.h>
+#include <linux/percpu.h>
+
+/*
+ * dbs is used in this file as a shortform for demandbased switching
+ * It helps to keep variable names smaller, simpler
+ */
+
+#define DEF_FREQUENCY_UP_THRESHOLD (80)
+#define MIN_FREQUENCY_UP_THRESHOLD (0)
+#define MAX_FREQUENCY_UP_THRESHOLD (100)
+
+#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
+#define MIN_FREQUENCY_DOWN_THRESHOLD (0)
+#define MAX_FREQUENCY_DOWN_THRESHOLD (100)
+
+/*
+ * The polling frequency of this governor depends on the capability of
+ * the processor. Default polling frequency is 1000 times the transition
+ * latency of the processor. The governor will work on any processor with
+ * transition latency <= 10mS, using appropriate sampling
+ * rate.
+ * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
+ * this governor will not work.
+ * All times here are in uS.
+ */
+static unsigned int def_sampling_rate;
+#define MIN_SAMPLING_RATE (def_sampling_rate / 2)
+#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
+#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (100000)
+#define DEF_SAMPLING_DOWN_FACTOR (5)
+#define TRANSITION_LATENCY_LIMIT (10 * 1000)
+
+static void do_dbs_timer(void *data);
+
+struct cpu_dbs_info_s {
+ struct cpufreq_policy *cur_policy;
+ unsigned int prev_cpu_idle_up;
+ unsigned int prev_cpu_idle_down;
+ unsigned int enable;
+};
+static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
+
+static unsigned int dbs_enable; /* number of CPUs using this policy */
+
+static DECLARE_MUTEX (dbs_sem);
+static DECLARE_WORK (dbs_work, do_dbs_timer, NULL);
+
+struct dbs_tuners {
+ unsigned int sampling_rate;
+ unsigned int sampling_down_factor;
+ unsigned int up_threshold;
+ unsigned int down_threshold;
+ unsigned int ignore_nice;
+ unsigned int freq_step;
+};
+
+static struct dbs_tuners dbs_tuners_ins = {
+ .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
+ .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
+ .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
+};
+
+/************************** sysfs interface ************************/
+static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
+{
+ return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
+}
+
+static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
+{
+ return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
+}
+
+#define define_one_ro(_name) \
+static struct freq_attr _name = \
+__ATTR(_name, 0444, show_##_name, NULL)
+
+define_one_ro(sampling_rate_max);
+define_one_ro(sampling_rate_min);
+
+/* cpufreq_conservative Governor Tunables */
+#define show_one(file_name, object) \
+static ssize_t show_##file_name \
+(struct cpufreq_policy *unused, char *buf) \
+{ \
+ return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
+}
+show_one(sampling_rate, sampling_rate);
+show_one(sampling_down_factor, sampling_down_factor);
+show_one(up_threshold, up_threshold);
+show_one(down_threshold, down_threshold);
+show_one(ignore_nice, ignore_nice);
+show_one(freq_step, freq_step);
+
+static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+ if (ret != 1 )
+ return -EINVAL;
+
+ down(&dbs_sem);
+ dbs_tuners_ins.sampling_down_factor = input;
+ up(&dbs_sem);
+
+ return count;
+}
+
+static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+
+ down(&dbs_sem);
+ if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
+ up(&dbs_sem);
+ return -EINVAL;
+ }
+
+ dbs_tuners_ins.sampling_rate = input;
+ up(&dbs_sem);
+
+ return count;
+}
+
+static ssize_t store_up_threshold(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+
+ down(&dbs_sem);
+ if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
+ input < MIN_FREQUENCY_UP_THRESHOLD ||
+ input <= dbs_tuners_ins.down_threshold) {
+ up(&dbs_sem);
+ return -EINVAL;
+ }
+
+ dbs_tuners_ins.up_threshold = input;
+ up(&dbs_sem);
+
+ return count;
+}
+
+static ssize_t store_down_threshold(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+
+ down(&dbs_sem);
+ if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD ||
+ input < MIN_FREQUENCY_DOWN_THRESHOLD ||
+ input >= dbs_tuners_ins.up_threshold) {
+ up(&dbs_sem);
+ return -EINVAL;
+ }
+
+ dbs_tuners_ins.down_threshold = input;
+ up(&dbs_sem);
+
+ return count;
+}
+
+static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+
+ unsigned int j;
+
+ ret = sscanf (buf, "%u", &input);
+ if ( ret != 1 )
+ return -EINVAL;
+
+ if ( input > 1 )
+ input = 1;
+
+ down(&dbs_sem);
+ if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
+ up(&dbs_sem);
+ return count;
+ }
+ dbs_tuners_ins.ignore_nice = input;
+
+ /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
+ for_each_cpu_mask(j, policy->cpus) {
+ struct cpu_dbs_info_s *j_dbs_info;
+ j_dbs_info = &per_cpu(cpu_dbs_info, j);
+ j_dbs_info->cur_policy = policy;
+
+ j_dbs_info->prev_cpu_idle_up =
+ kstat_cpu(j).cpustat.idle +
+ kstat_cpu(j).cpustat.iowait +
+ ( !dbs_tuners_ins.ignore_nice
+ ? kstat_cpu(j).cpustat.nice : 0 );
+ j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
+ }
+ up(&dbs_sem);
+
+ return count;
+}
+
+static ssize_t store_freq_step(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+
+ ret = sscanf (buf, "%u", &input);
+
+ if ( ret != 1 )
+ return -EINVAL;
+
+ if ( input > 100 )
+ input = 100;
+
+ /* no need to test here if freq_step is zero as the user might actually
+ * want this, they would be crazy though :) */
+ down(&dbs_sem);
+ dbs_tuners_ins.freq_step = input;
+ up(&dbs_sem);
+
+ return count;
+}
+
+#define define_one_rw(_name) \
+static struct freq_attr _name = \
+__ATTR(_name, 0644, show_##_name, store_##_name)
+
+define_one_rw(sampling_rate);
+define_one_rw(sampling_down_factor);
+define_one_rw(up_threshold);
+define_one_rw(down_threshold);
+define_one_rw(ignore_nice);
+define_one_rw(freq_step);
+
+static struct attribute * dbs_attributes[] = {
+ &sampling_rate_max.attr,
+ &sampling_rate_min.attr,
+ &sampling_rate.attr,
+ &sampling_down_factor.attr,
+ &up_threshold.attr,
+ &down_threshold.attr,
+ &ignore_nice.attr,
+ &freq_step.attr,
+ NULL
+};
+
+static struct attribute_group dbs_attr_group = {
+ .attrs = dbs_attributes,
+ .name = "conservative",
+};
+
+/************************** sysfs end ************************/
+
+static void dbs_check_cpu(int cpu)
+{
+ unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
+ unsigned int total_idle_ticks;
+ unsigned int freq_step;
+ unsigned int freq_down_sampling_rate;
+ static int down_skip[NR_CPUS];
+ static int requested_freq[NR_CPUS];
+ static unsigned short init_flag = 0;
+ struct cpu_dbs_info_s *this_dbs_info;
+ struct cpu_dbs_info_s *dbs_info;
+
+ struct cpufreq_policy *policy;
+ unsigned int j;
+
+ this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+ if (!this_dbs_info->enable)
+ return;
+
+ policy = this_dbs_info->cur_policy;
+
+ if ( init_flag == 0 ) {
+ for ( /* NULL */; init_flag < NR_CPUS; init_flag++ ) {
+ dbs_info = &per_cpu(cpu_dbs_info, init_flag);
+ requested_freq[cpu] = dbs_info->cur_policy->cur;
+ }
+ init_flag = 1;
+ }
+
+ /*
+ * The default safe range is 20% to 80%
+ * Every sampling_rate, we check
+ * - If current idle time is less than 20%, then we try to
+ * increase frequency
+ * Every sampling_rate*sampling_down_factor, we check
+ * - If current idle time is more than 80%, then we try to
+ * decrease frequency
+ *
+ * Any frequency increase takes it to the maximum frequency.
+ * Frequency reduction happens at minimum steps of
+ * 5% (default) of max_frequency
+ */
+
+ /* Check for frequency increase */
+ total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
+ kstat_cpu(cpu).cpustat.iowait;
+ /* consider 'nice' tasks as 'idle' time too if required */
+ if (dbs_tuners_ins.ignore_nice == 0)
+ total_idle_ticks += kstat_cpu(cpu).cpustat.nice;
+ idle_ticks = total_idle_ticks -
+ this_dbs_info->prev_cpu_idle_up;
+ this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
+
+
+ for_each_cpu_mask(j, policy->cpus) {
+ unsigned int tmp_idle_ticks;
+ struct cpu_dbs_info_s *j_dbs_info;
+
+ if (j == cpu)
+ continue;
+
+ j_dbs_info = &per_cpu(cpu_dbs_info, j);
+ /* Check for frequency increase */
+ total_idle_ticks = kstat_cpu(j).cpustat.idle +
+ kstat_cpu(j).cpustat.iowait;
+ /* consider 'nice' too? */
+ if (dbs_tuners_ins.ignore_nice == 0)
+ total_idle_ticks += kstat_cpu(j).cpustat.nice;
+ tmp_idle_ticks = total_idle_ticks -
+ j_dbs_info->prev_cpu_idle_up;
+ j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
+
+ if (tmp_idle_ticks < idle_ticks)
+ idle_ticks = tmp_idle_ticks;
+ }
+
+ /* Scale idle ticks by 100 and compare with up and down ticks */
+ idle_ticks *= 100;
+ up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
+ usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+
+ if (idle_ticks < up_idle_ticks) {
+ /* if we are already at full speed then break out early */
+ if (requested_freq[cpu] == policy->max)
+ return;
+
+ freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
+
+ /* max freq cannot be less than 100. But who knows.... */
+ if (unlikely(freq_step == 0))
+ freq_step = 5;
+
+ requested_freq[cpu] += freq_step;
+ if (requested_freq[cpu] > policy->max)
+ requested_freq[cpu] = policy->max;
+
+ __cpufreq_driver_target(policy, requested_freq[cpu],
+ CPUFREQ_RELATION_H);
+ down_skip[cpu] = 0;
+ this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
+ return;
+ }
+
+ /* Check for frequency decrease */
+ down_skip[cpu]++;
+ if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
+ return;
+
+ total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
+ kstat_cpu(cpu).cpustat.iowait;
+ /* consider 'nice' too? */
+ if (dbs_tuners_ins.ignore_nice == 0)
+ total_idle_ticks += kstat_cpu(cpu).cpustat.nice;
+ idle_ticks = total_idle_ticks -
+ this_dbs_info->prev_cpu_idle_down;
+ this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
+
+ for_each_cpu_mask(j, policy->cpus) {
+ unsigned int tmp_idle_ticks;
+ struct cpu_dbs_info_s *j_dbs_info;
+
+ if (j == cpu)
+ continue;
+
+ j_dbs_info = &per_cpu(cpu_dbs_info, j);
+ /* Check for frequency increase */
+ total_idle_ticks = kstat_cpu(j).cpustat.idle +
+ kstat_cpu(j).cpustat.iowait;
+ /* consider 'nice' too? */
+ if (dbs_tuners_ins.ignore_nice == 0)
+ total_idle_ticks += kstat_cpu(j).cpustat.nice;
+ tmp_idle_ticks = total_idle_ticks -
+ j_dbs_info->prev_cpu_idle_down;
+ j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
+
+ if (tmp_idle_ticks < idle_ticks)
+ idle_ticks = tmp_idle_ticks;
+ }
+
+ /* Scale idle ticks by 100 and compare with up and down ticks */
+ idle_ticks *= 100;
+ down_skip[cpu] = 0;
+
+ freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
+ dbs_tuners_ins.sampling_down_factor;
+ down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
+ usecs_to_jiffies(freq_down_sampling_rate);
+
+ if (idle_ticks > down_idle_ticks ) {
+ /* if we are already at the lowest speed then break out early
+ * or if we 'cannot' reduce the speed as the user might want
+ * freq_step to be zero */
+ if (requested_freq[cpu] == policy->min
+ || dbs_tuners_ins.freq_step == 0)
+ return;
+
+ freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
+
+ /* max freq cannot be less than 100. But who knows.... */
+ if (unlikely(freq_step == 0))
+ freq_step = 5;
+
+ requested_freq[cpu] -= freq_step;
+ if (requested_freq[cpu] < policy->min)
+ requested_freq[cpu] = policy->min;
+
+ __cpufreq_driver_target(policy,
+ requested_freq[cpu],
+ CPUFREQ_RELATION_H);
+ return;
+ }
+}
+
+static void do_dbs_timer(void *data)
+{
+ int i;
+ down(&dbs_sem);
+ for_each_online_cpu(i)
+ dbs_check_cpu(i);
+ schedule_delayed_work(&dbs_work,
+ usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
+ up(&dbs_sem);
+}
+
+static inline void dbs_timer_init(void)
+{
+ INIT_WORK(&dbs_work, do_dbs_timer, NULL);
+ schedule_delayed_work(&dbs_work,
+ usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
+ return;
+}
+
+static inline void dbs_timer_exit(void)
+{
+ cancel_delayed_work(&dbs_work);
+ return;
+}
+
+static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
+ unsigned int event)
+{
+ unsigned int cpu = policy->cpu;
+ struct cpu_dbs_info_s *this_dbs_info;
+ unsigned int j;
+
+ this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+
+ switch (event) {
+ case CPUFREQ_GOV_START:
+ if ((!cpu_online(cpu)) ||
+ (!policy->cur))
+ return -EINVAL;
+
+ if (policy->cpuinfo.transition_latency >
+ (TRANSITION_LATENCY_LIMIT * 1000))
+ return -EINVAL;
+ if (this_dbs_info->enable) /* Already enabled */
+ break;
+
+ down(&dbs_sem);
+ for_each_cpu_mask(j, policy->cpus) {
+ struct cpu_dbs_info_s *j_dbs_info;
+ j_dbs_info = &per_cpu(cpu_dbs_info, j);
+ j_dbs_info->cur_policy = policy;
+
+ j_dbs_info->prev_cpu_idle_up =
+ kstat_cpu(j).cpustat.idle +
+ kstat_cpu(j).cpustat.iowait +
+ ( !dbs_tuners_ins.ignore_nice
+ ? kstat_cpu(j).cpustat.nice : 0 );
+ j_dbs_info->prev_cpu_idle_down
+ = j_dbs_info->prev_cpu_idle_up;
+ }
+ this_dbs_info->enable = 1;
+ sysfs_create_group(&policy->kobj, &dbs_attr_group);
+ dbs_enable++;
+ /*
+ * Start the timerschedule work, when this governor
+ * is used for first time
+ */
+ if (dbs_enable == 1) {
+ unsigned int latency;
+ /* policy latency is in nS. Convert it to uS first */
+
+ latency = policy->cpuinfo.transition_latency;
+ if (latency < 1000)
+ latency = 1000;
+
+ def_sampling_rate = (latency / 1000) *
+ DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
+ dbs_tuners_ins.sampling_rate = def_sampling_rate;
+ dbs_tuners_ins.ignore_nice = 0;
+ dbs_tuners_ins.freq_step = 5;
+
+ dbs_timer_init();
+ }
+
+ up(&dbs_sem);
+ break;
+
+ case CPUFREQ_GOV_STOP:
+ down(&dbs_sem);
+ this_dbs_info->enable = 0;
+ sysfs_remove_group(&policy->kobj, &dbs_attr_group);
+ dbs_enable--;
+ /*
+ * Stop the timerschedule work, when this governor
+ * is used for first time
+ */
+ if (dbs_enable == 0)
+ dbs_timer_exit();
+
+ up(&dbs_sem);
+
+ break;
+
+ case CPUFREQ_GOV_LIMITS:
+ down(&dbs_sem);
+ if (policy->max < this_dbs_info->cur_policy->cur)
+ __cpufreq_driver_target(
+ this_dbs_info->cur_policy,
+ policy->max, CPUFREQ_RELATION_H);
+ else if (policy->min > this_dbs_info->cur_policy->cur)
+ __cpufreq_driver_target(
+ this_dbs_info->cur_policy,
+ policy->min, CPUFREQ_RELATION_L);
+ up(&dbs_sem);
+ break;
+ }
+ return 0;
+}
+
+static struct cpufreq_governor cpufreq_gov_dbs = {
+ .name = "conservative",
+ .governor = cpufreq_governor_dbs,
+ .owner = THIS_MODULE,
+};
+
+static int __init cpufreq_gov_dbs_init(void)
+{
+ return cpufreq_register_governor(&cpufreq_gov_dbs);
+}
+
+static void __exit cpufreq_gov_dbs_exit(void)
+{
+ /* Make sure that the scheduled work is indeed not running */
+ flush_scheduled_work();
+
+ cpufreq_unregister_governor(&cpufreq_gov_dbs);
+}
+
+
+MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>");
+MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
+ "Low Latency Frequency Transition capable processors "
+ "optimised for use in a battery environment");
+MODULE_LICENSE ("GPL");
+
+module_init(cpufreq_gov_dbs_init);
+module_exit(cpufreq_gov_dbs_exit);
projects / linux-2.6 / commitdiff