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linux-next/drivers/cpufreq/cpufreq_ondemand.c
Stratos Karafotis 06eb09d17c cpufreq: ondemand: Fix typos in comments
Fix some typos in comments.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-02-09 12:56:19 +01:00

555 lines
16 KiB
C

/*
* drivers/cpufreq/cpufreq_ondemand.c
*
* Copyright (C) 2001 Russell King
* (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
* Jun Nakajima <jun.nakajima@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 <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/percpu-defs.h>
#include <linux/sysfs.h>
#include <linux/tick.h>
#include <linux/types.h>
#include "cpufreq_governor.h"
/* On-demand governor macros */
#define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10)
#define DEF_FREQUENCY_UP_THRESHOLD (80)
#define DEF_SAMPLING_DOWN_FACTOR (1)
#define MAX_SAMPLING_DOWN_FACTOR (100000)
#define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3)
#define MICRO_FREQUENCY_UP_THRESHOLD (95)
#define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
#define MIN_FREQUENCY_UP_THRESHOLD (11)
#define MAX_FREQUENCY_UP_THRESHOLD (100)
static struct dbs_data od_dbs_data;
static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
static struct cpufreq_governor cpufreq_gov_ondemand;
#endif
static struct od_dbs_tuners od_tuners = {
.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
.adj_up_threshold = DEF_FREQUENCY_UP_THRESHOLD -
DEF_FREQUENCY_DOWN_DIFFERENTIAL,
.ignore_nice = 0,
.powersave_bias = 0,
};
static void ondemand_powersave_bias_init_cpu(int cpu)
{
struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
dbs_info->freq_lo = 0;
}
/*
* Not all CPUs want IO time to be accounted as busy; this depends on how
* efficient idling at a higher frequency/voltage is.
* Pavel Machek says this is not so for various generations of AMD and old
* Intel systems.
* Mike Chan (android.com) claims this is also not true for ARM.
* Because of this, whitelist specific known (series) of CPUs by default, and
* leave all others up to the user.
*/
static int should_io_be_busy(void)
{
#if defined(CONFIG_X86)
/*
* For Intel, Core 2 (model 15) and later have an efficient idle.
*/
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
boot_cpu_data.x86 == 6 &&
boot_cpu_data.x86_model >= 15)
return 1;
#endif
return 0;
}
/*
* Find right freq to be set now with powersave_bias on.
* Returns the freq_hi to be used right now and will set freq_hi_jiffies,
* freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
*/
static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
unsigned int freq_next, unsigned int relation)
{
unsigned int freq_req, freq_reduc, freq_avg;
unsigned int freq_hi, freq_lo;
unsigned int index = 0;
unsigned int jiffies_total, jiffies_hi, jiffies_lo;
struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
policy->cpu);
if (!dbs_info->freq_table) {
dbs_info->freq_lo = 0;
dbs_info->freq_lo_jiffies = 0;
return freq_next;
}
cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
relation, &index);
freq_req = dbs_info->freq_table[index].frequency;
freq_reduc = freq_req * od_tuners.powersave_bias / 1000;
freq_avg = freq_req - freq_reduc;
/* Find freq bounds for freq_avg in freq_table */
index = 0;
cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
CPUFREQ_RELATION_H, &index);
freq_lo = dbs_info->freq_table[index].frequency;
index = 0;
cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
CPUFREQ_RELATION_L, &index);
freq_hi = dbs_info->freq_table[index].frequency;
/* Find out how long we have to be in hi and lo freqs */
if (freq_hi == freq_lo) {
dbs_info->freq_lo = 0;
dbs_info->freq_lo_jiffies = 0;
return freq_lo;
}
jiffies_total = usecs_to_jiffies(od_tuners.sampling_rate);
jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
jiffies_hi += ((freq_hi - freq_lo) / 2);
jiffies_hi /= (freq_hi - freq_lo);
jiffies_lo = jiffies_total - jiffies_hi;
dbs_info->freq_lo = freq_lo;
dbs_info->freq_lo_jiffies = jiffies_lo;
dbs_info->freq_hi_jiffies = jiffies_hi;
return freq_hi;
}
static void ondemand_powersave_bias_init(void)
{
int i;
for_each_online_cpu(i) {
ondemand_powersave_bias_init_cpu(i);
}
}
static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
{
if (od_tuners.powersave_bias)
freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
else if (p->cur == p->max)
return;
__cpufreq_driver_target(p, freq, od_tuners.powersave_bias ?
CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
}
/*
* Every sampling_rate, we check, if current idle time is less than 20%
* (default), then we try to increase frequency. Every sampling_rate, we look
* for the lowest frequency which can sustain the load while keeping idle time
* over 30%. If such a frequency exist, we try to decrease to this frequency.
*
* Any frequency increase takes it to the maximum frequency. Frequency reduction
* happens at minimum steps of 5% (default) of current frequency
*/
static void od_check_cpu(int cpu, unsigned int load_freq)
{
struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
dbs_info->freq_lo = 0;
/* Check for frequency increase */
if (load_freq > od_tuners.up_threshold * policy->cur) {
/* If switching to max speed, apply sampling_down_factor */
if (policy->cur < policy->max)
dbs_info->rate_mult =
od_tuners.sampling_down_factor;
dbs_freq_increase(policy, policy->max);
return;
}
/* Check for frequency decrease */
/* if we cannot reduce the frequency anymore, break out early */
if (policy->cur == policy->min)
return;
/*
* The optimal frequency is the frequency that is the lowest that can
* support the current CPU usage without triggering the up policy. To be
* safe, we focus 10 points under the threshold.
*/
if (load_freq < od_tuners.adj_up_threshold * policy->cur) {
unsigned int freq_next;
freq_next = load_freq / od_tuners.adj_up_threshold;
/* No longer fully busy, reset rate_mult */
dbs_info->rate_mult = 1;
if (freq_next < policy->min)
freq_next = policy->min;
if (!od_tuners.powersave_bias) {
__cpufreq_driver_target(policy, freq_next,
CPUFREQ_RELATION_L);
} else {
int freq = powersave_bias_target(policy, freq_next,
CPUFREQ_RELATION_L);
__cpufreq_driver_target(policy, freq,
CPUFREQ_RELATION_L);
}
}
}
static void od_dbs_timer(struct work_struct *work)
{
struct delayed_work *dw = to_delayed_work(work);
struct od_cpu_dbs_info_s *dbs_info =
container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
struct od_cpu_dbs_info_s *core_dbs_info = &per_cpu(od_cpu_dbs_info,
cpu);
int delay, sample_type = core_dbs_info->sample_type;
bool eval_load;
mutex_lock(&core_dbs_info->cdbs.timer_mutex);
eval_load = need_load_eval(&core_dbs_info->cdbs,
od_tuners.sampling_rate);
/* Common NORMAL_SAMPLE setup */
core_dbs_info->sample_type = OD_NORMAL_SAMPLE;
if (sample_type == OD_SUB_SAMPLE) {
delay = core_dbs_info->freq_lo_jiffies;
if (eval_load)
__cpufreq_driver_target(core_dbs_info->cdbs.cur_policy,
core_dbs_info->freq_lo,
CPUFREQ_RELATION_H);
} else {
if (eval_load)
dbs_check_cpu(&od_dbs_data, cpu);
if (core_dbs_info->freq_lo) {
/* Setup timer for SUB_SAMPLE */
core_dbs_info->sample_type = OD_SUB_SAMPLE;
delay = core_dbs_info->freq_hi_jiffies;
} else {
delay = delay_for_sampling_rate(od_tuners.sampling_rate
* core_dbs_info->rate_mult);
}
}
schedule_delayed_work_on(smp_processor_id(), dw, delay);
mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
}
/************************** sysfs interface ************************/
static ssize_t show_sampling_rate_min(struct kobject *kobj,
struct attribute *attr, char *buf)
{
return sprintf(buf, "%u\n", od_dbs_data.min_sampling_rate);
}
/**
* update_sampling_rate - update sampling rate effective immediately if needed.
* @new_rate: new sampling rate
*
* If new rate is smaller than the old, simply updating
* dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
* original sampling_rate was 1 second and the requested new sampling rate is 10
* ms because the user needs immediate reaction from ondemand governor, but not
* sure if higher frequency will be required or not, then, the governor may
* change the sampling rate too late; up to 1 second later. Thus, if we are
* reducing the sampling rate, we need to make the new value effective
* immediately.
*/
static void update_sampling_rate(unsigned int new_rate)
{
int cpu;
od_tuners.sampling_rate = new_rate = max(new_rate,
od_dbs_data.min_sampling_rate);
for_each_online_cpu(cpu) {
struct cpufreq_policy *policy;
struct od_cpu_dbs_info_s *dbs_info;
unsigned long next_sampling, appointed_at;
policy = cpufreq_cpu_get(cpu);
if (!policy)
continue;
if (policy->governor != &cpufreq_gov_ondemand) {
cpufreq_cpu_put(policy);
continue;
}
dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
cpufreq_cpu_put(policy);
mutex_lock(&dbs_info->cdbs.timer_mutex);
if (!delayed_work_pending(&dbs_info->cdbs.work)) {
mutex_unlock(&dbs_info->cdbs.timer_mutex);
continue;
}
next_sampling = jiffies + usecs_to_jiffies(new_rate);
appointed_at = dbs_info->cdbs.work.timer.expires;
if (time_before(next_sampling, appointed_at)) {
mutex_unlock(&dbs_info->cdbs.timer_mutex);
cancel_delayed_work_sync(&dbs_info->cdbs.work);
mutex_lock(&dbs_info->cdbs.timer_mutex);
schedule_delayed_work_on(cpu, &dbs_info->cdbs.work,
usecs_to_jiffies(new_rate));
}
mutex_unlock(&dbs_info->cdbs.timer_mutex);
}
}
static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
const char *buf, size_t count)
{
unsigned int input;
int ret;
ret = sscanf(buf, "%u", &input);
if (ret != 1)
return -EINVAL;
update_sampling_rate(input);
return count;
}
static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
const char *buf, size_t count)
{
unsigned int input;
int ret;
ret = sscanf(buf, "%u", &input);
if (ret != 1)
return -EINVAL;
od_tuners.io_is_busy = !!input;
return count;
}
static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
const char *buf, size_t count)
{
unsigned int input;
int ret;
ret = sscanf(buf, "%u", &input);
if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
input < MIN_FREQUENCY_UP_THRESHOLD) {
return -EINVAL;
}
/* Calculate the new adj_up_threshold */
od_tuners.adj_up_threshold += input;
od_tuners.adj_up_threshold -= od_tuners.up_threshold;
od_tuners.up_threshold = input;
return count;
}
static ssize_t store_sampling_down_factor(struct kobject *a,
struct attribute *b, const char *buf, size_t count)
{
unsigned int input, j;
int ret;
ret = sscanf(buf, "%u", &input);
if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
return -EINVAL;
od_tuners.sampling_down_factor = input;
/* Reset down sampling multiplier in case it was active */
for_each_online_cpu(j) {
struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
j);
dbs_info->rate_mult = 1;
}
return count;
}
static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
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;
if (input == od_tuners.ignore_nice) { /* nothing to do */
return count;
}
od_tuners.ignore_nice = input;
/* we need to re-evaluate prev_cpu_idle */
for_each_online_cpu(j) {
struct od_cpu_dbs_info_s *dbs_info;
dbs_info = &per_cpu(od_cpu_dbs_info, j);
dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
&dbs_info->cdbs.prev_cpu_wall);
if (od_tuners.ignore_nice)
dbs_info->cdbs.prev_cpu_nice =
kcpustat_cpu(j).cpustat[CPUTIME_NICE];
}
return count;
}
static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
const char *buf, size_t count)
{
unsigned int input;
int ret;
ret = sscanf(buf, "%u", &input);
if (ret != 1)
return -EINVAL;
if (input > 1000)
input = 1000;
od_tuners.powersave_bias = input;
ondemand_powersave_bias_init();
return count;
}
show_one(od, sampling_rate, sampling_rate);
show_one(od, io_is_busy, io_is_busy);
show_one(od, up_threshold, up_threshold);
show_one(od, sampling_down_factor, sampling_down_factor);
show_one(od, ignore_nice_load, ignore_nice);
show_one(od, powersave_bias, powersave_bias);
define_one_global_rw(sampling_rate);
define_one_global_rw(io_is_busy);
define_one_global_rw(up_threshold);
define_one_global_rw(sampling_down_factor);
define_one_global_rw(ignore_nice_load);
define_one_global_rw(powersave_bias);
define_one_global_ro(sampling_rate_min);
static struct attribute *dbs_attributes[] = {
&sampling_rate_min.attr,
&sampling_rate.attr,
&up_threshold.attr,
&sampling_down_factor.attr,
&ignore_nice_load.attr,
&powersave_bias.attr,
&io_is_busy.attr,
NULL
};
static struct attribute_group od_attr_group = {
.attrs = dbs_attributes,
.name = "ondemand",
};
/************************** sysfs end ************************/
define_get_cpu_dbs_routines(od_cpu_dbs_info);
static struct od_ops od_ops = {
.io_busy = should_io_be_busy,
.powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
.powersave_bias_target = powersave_bias_target,
.freq_increase = dbs_freq_increase,
};
static struct dbs_data od_dbs_data = {
.governor = GOV_ONDEMAND,
.attr_group = &od_attr_group,
.tuners = &od_tuners,
.get_cpu_cdbs = get_cpu_cdbs,
.get_cpu_dbs_info_s = get_cpu_dbs_info_s,
.gov_dbs_timer = od_dbs_timer,
.gov_check_cpu = od_check_cpu,
.gov_ops = &od_ops,
};
static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
unsigned int event)
{
return cpufreq_governor_dbs(&od_dbs_data, policy, event);
}
#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
static
#endif
struct cpufreq_governor cpufreq_gov_ondemand = {
.name = "ondemand",
.governor = od_cpufreq_governor_dbs,
.max_transition_latency = TRANSITION_LATENCY_LIMIT,
.owner = THIS_MODULE,
};
static int __init cpufreq_gov_dbs_init(void)
{
u64 idle_time;
int cpu = get_cpu();
mutex_init(&od_dbs_data.mutex);
idle_time = get_cpu_idle_time_us(cpu, NULL);
put_cpu();
if (idle_time != -1ULL) {
/* Idle micro accounting is supported. Use finer thresholds */
od_tuners.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
od_tuners.adj_up_threshold = MICRO_FREQUENCY_UP_THRESHOLD -
MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
/*
* In nohz/micro accounting case we set the minimum frequency
* not depending on HZ, but fixed (very low). The deferred
* timer might skip some samples if idle/sleeping as needed.
*/
od_dbs_data.min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
} else {
/* For correct statistics, we need 10 ticks for each measure */
od_dbs_data.min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
jiffies_to_usecs(10);
}
return cpufreq_register_governor(&cpufreq_gov_ondemand);
}
static void __exit cpufreq_gov_dbs_exit(void)
{
cpufreq_unregister_governor(&cpufreq_gov_ondemand);
}
MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
"Low Latency Frequency Transition capable processors");
MODULE_LICENSE("GPL");
#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
fs_initcall(cpufreq_gov_dbs_init);
#else
module_init(cpufreq_gov_dbs_init);
#endif
module_exit(cpufreq_gov_dbs_exit);