linux/drivers/cpufreq/cpufreq_conservative.c

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/*
* 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) 2009 Alexander Clouter <alex@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/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/notifier.h>
#include <linux/percpu-defs.h>
#include <linux/sysfs.h>
#include <linux/types.h>
#include "cpufreq_governor.h"
/* Conservative governor macors */
#define DEF_FREQUENCY_UP_THRESHOLD (80)
#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
#define DEF_SAMPLING_DOWN_FACTOR (1)
#define MAX_SAMPLING_DOWN_FACTOR (10)
static struct dbs_data cs_dbs_data;
static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
static struct cs_dbs_tuners cs_tuners = {
.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
.down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
.ignore_nice = 0,
.freq_step = 5,
};
/*
* Every sampling_rate, we check, if current idle time is less than 20%
* (default), 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 maximum frequency
*/
static void cs_check_cpu(int cpu, unsigned int load)
{
struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
unsigned int freq_target;
/*
* break out if we 'cannot' reduce the speed as the user might
* want freq_step to be zero
*/
if (cs_tuners.freq_step == 0)
return;
/* Check for frequency increase */
if (load > cs_tuners.up_threshold) {
dbs_info->down_skip = 0;
/* if we are already at full speed then break out early */
if (dbs_info->requested_freq == policy->max)
return;
freq_target = (cs_tuners.freq_step * policy->max) / 100;
/* max freq cannot be less than 100. But who knows.... */
if (unlikely(freq_target == 0))
freq_target = 5;
dbs_info->requested_freq += freq_target;
if (dbs_info->requested_freq > policy->max)
dbs_info->requested_freq = policy->max;
__cpufreq_driver_target(policy, dbs_info->requested_freq,
CPUFREQ_RELATION_H);
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 < (cs_tuners.down_threshold - 10)) {
freq_target = (cs_tuners.freq_step * policy->max) / 100;
dbs_info->requested_freq -= freq_target;
if (dbs_info->requested_freq < policy->min)
dbs_info->requested_freq = policy->min;
/*
* if we cannot reduce the frequency anymore, break out early
*/
if (policy->cur == policy->min)
return;
__cpufreq_driver_target(policy, dbs_info->requested_freq,
CPUFREQ_RELATION_H);
return;
}
}
static void cs_dbs_timer(struct work_struct *work)
{
struct delayed_work *dw = to_delayed_work(work);
struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
struct cs_cpu_dbs_info_s, cdbs.work.work);
unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
struct cs_cpu_dbs_info_s *core_dbs_info = &per_cpu(cs_cpu_dbs_info,
cpu);
int delay = delay_for_sampling_rate(cs_tuners.sampling_rate);
mutex_lock(&core_dbs_info->cdbs.timer_mutex);
if (need_load_eval(&core_dbs_info->cdbs, cs_tuners.sampling_rate))
dbs_check_cpu(&cs_dbs_data, cpu);
schedule_delayed_work_on(smp_processor_id(), dw, delay);
mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
}
static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
void *data)
{
struct cpufreq_freqs *freq = data;
struct cs_cpu_dbs_info_s *dbs_info =
&per_cpu(cs_cpu_dbs_info, freq->cpu);
struct cpufreq_policy *policy;
if (!dbs_info->enable)
return 0;
policy = dbs_info->cdbs.cur_policy;
/*
* we only care if our internally tracked freq moves outside the 'valid'
* ranges of freqency available to us otherwise we do not change it
*/
if (dbs_info->requested_freq > policy->max
|| dbs_info->requested_freq < policy->min)
dbs_info->requested_freq = freq->new;
return 0;
}
/************************** sysfs interface ************************/
static ssize_t show_sampling_rate_min(struct kobject *kobj,
struct attribute *attr, char *buf)
{
return sprintf(buf, "%u\n", cs_dbs_data.min_sampling_rate);
}
static ssize_t store_sampling_down_factor(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_SAMPLING_DOWN_FACTOR || input < 1)
return -EINVAL;
cs_tuners.sampling_down_factor = input;
return count;
}
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;
cs_tuners.sampling_rate = max(input, cs_dbs_data.min_sampling_rate);
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 > 100 || input <= cs_tuners.down_threshold)
return -EINVAL;
cs_tuners.up_threshold = input;
return count;
}
static ssize_t store_down_threshold(struct kobject *a, struct attribute *b,
const char *buf, size_t count)
{
unsigned int input;
int ret;
ret = sscanf(buf, "%u", &input);
/* cannot be lower than 11 otherwise freq will not fall */
if (ret != 1 || input < 11 || input > 100 ||
input >= cs_tuners.up_threshold)
return -EINVAL;
cs_tuners.down_threshold = input;
return count;
}
static ssize_t store_ignore_nice_load(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)
return -EINVAL;
if (input > 1)
input = 1;
if (input == cs_tuners.ignore_nice) /* nothing to do */
return count;
cs_tuners.ignore_nice = input;
/* we need to re-evaluate prev_cpu_idle */
for_each_online_cpu(j) {
struct cs_cpu_dbs_info_s *dbs_info;
dbs_info = &per_cpu(cs_cpu_dbs_info, j);
dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
&dbs_info->cdbs.prev_cpu_wall);
if (cs_tuners.ignore_nice)
dbs_info->cdbs.prev_cpu_nice =
kcpustat_cpu(j).cpustat[CPUTIME_NICE];
}
return count;
}
static ssize_t store_freq_step(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 > 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 :)
*/
cs_tuners.freq_step = input;
return count;
}
show_one(cs, sampling_rate, sampling_rate);
show_one(cs, sampling_down_factor, sampling_down_factor);
show_one(cs, up_threshold, up_threshold);
show_one(cs, down_threshold, down_threshold);
show_one(cs, ignore_nice_load, ignore_nice);
show_one(cs, freq_step, freq_step);
define_one_global_rw(sampling_rate);
define_one_global_rw(sampling_down_factor);
define_one_global_rw(up_threshold);
define_one_global_rw(down_threshold);
define_one_global_rw(ignore_nice_load);
define_one_global_rw(freq_step);
define_one_global_ro(sampling_rate_min);
static struct attribute *dbs_attributes[] = {
&sampling_rate_min.attr,
&sampling_rate.attr,
&sampling_down_factor.attr,
&up_threshold.attr,
&down_threshold.attr,
&ignore_nice_load.attr,
&freq_step.attr,
NULL
};
static struct attribute_group cs_attr_group = {
.attrs = dbs_attributes,
.name = "conservative",
};
/************************** sysfs end ************************/
define_get_cpu_dbs_routines(cs_cpu_dbs_info);
static struct notifier_block cs_cpufreq_notifier_block = {
.notifier_call = dbs_cpufreq_notifier,
};
static struct cs_ops cs_ops = {
.notifier_block = &cs_cpufreq_notifier_block,
};
static struct dbs_data cs_dbs_data = {
.governor = GOV_CONSERVATIVE,
.attr_group = &cs_attr_group,
.tuners = &cs_tuners,
.get_cpu_cdbs = get_cpu_cdbs,
.get_cpu_dbs_info_s = get_cpu_dbs_info_s,
.gov_dbs_timer = cs_dbs_timer,
.gov_check_cpu = cs_check_cpu,
.gov_ops = &cs_ops,
};
static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
unsigned int event)
{
return cpufreq_governor_dbs(&cs_dbs_data, policy, event);
}
#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
static
#endif
struct cpufreq_governor cpufreq_gov_conservative = {
.name = "conservative",
.governor = cs_cpufreq_governor_dbs,
.max_transition_latency = TRANSITION_LATENCY_LIMIT,
.owner = THIS_MODULE,
};
static int __init cpufreq_gov_dbs_init(void)
{
mutex_init(&cs_dbs_data.mutex);
return cpufreq_register_governor(&cpufreq_gov_conservative);
}
static void __exit cpufreq_gov_dbs_exit(void)
{
cpufreq_unregister_governor(&cpufreq_gov_conservative);
}
MODULE_AUTHOR("Alexander Clouter <alex@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");
#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
fs_initcall(cpufreq_gov_dbs_init);
#else
module_init(cpufreq_gov_dbs_init);
#endif
module_exit(cpufreq_gov_dbs_exit);