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linux-next/drivers/cpufreq/cpufreq_ondemand.c
Viresh Kumar 2d04503632 cpufreq: governor: Drop min_sampling_rate
The cpufreq core and governors aren't supposed to set a limit on how
fast we want to try changing the frequency. This is currently done for
the legacy governors with help of min_sampling_rate.

At worst, we may end up setting the sampling rate to a value lower than
the rate at which frequency can be changed and then one of the CPUs in
the policy will be only changing frequency for ever.

But that is something for the user to decide and there is no need to
have special handling for such cases in the core. Leave it for the user
to figure out.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-22 02:25:20 +02:00

494 lines
13 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/cpu.h>
#include <linux/percpu-defs.h>
#include <linux/slab.h>
#include <linux/tick.h>
#include <linux/sched/cpufreq.h>
#include "cpufreq_ondemand.h"
/* On-demand governor macros */
#define DEF_FREQUENCY_UP_THRESHOLD (80)
#define DEF_SAMPLING_DOWN_FACTOR (1)
#define MAX_SAMPLING_DOWN_FACTOR (100000)
#define MICRO_FREQUENCY_UP_THRESHOLD (95)
#define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
#define MIN_FREQUENCY_UP_THRESHOLD (1)
#define MAX_FREQUENCY_UP_THRESHOLD (100)
static struct od_ops od_ops;
static unsigned int default_powersave_bias;
/*
* 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_delay_us,
* freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
*/
static unsigned int generic_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;
unsigned int delay_hi_us;
struct policy_dbs_info *policy_dbs = policy->governor_data;
struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
struct dbs_data *dbs_data = policy_dbs->dbs_data;
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
struct cpufreq_frequency_table *freq_table = policy->freq_table;
if (!freq_table) {
dbs_info->freq_lo = 0;
dbs_info->freq_lo_delay_us = 0;
return freq_next;
}
index = cpufreq_frequency_table_target(policy, freq_next, relation);
freq_req = 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 = cpufreq_table_find_index_h(policy, freq_avg);
freq_lo = freq_table[index].frequency;
index = cpufreq_table_find_index_l(policy, freq_avg);
freq_hi = 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_delay_us = 0;
return freq_lo;
}
delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
delay_hi_us += (freq_hi - freq_lo) / 2;
delay_hi_us /= freq_hi - freq_lo;
dbs_info->freq_hi_delay_us = delay_hi_us;
dbs_info->freq_lo = freq_lo;
dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
return freq_hi;
}
static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
{
struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
dbs_info->freq_lo = 0;
}
static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
{
struct policy_dbs_info *policy_dbs = policy->governor_data;
struct dbs_data *dbs_data = policy_dbs->dbs_data;
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
if (od_tuners->powersave_bias)
freq = od_ops.powersave_bias_target(policy, freq,
CPUFREQ_RELATION_H);
else if (policy->cur == policy->max)
return;
__cpufreq_driver_target(policy, 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. Else, we adjust the frequency
* proportional to load.
*/
static void od_update(struct cpufreq_policy *policy)
{
struct policy_dbs_info *policy_dbs = policy->governor_data;
struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
struct dbs_data *dbs_data = policy_dbs->dbs_data;
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
unsigned int load = dbs_update(policy);
dbs_info->freq_lo = 0;
/* Check for frequency increase */
if (load > dbs_data->up_threshold) {
/* If switching to max speed, apply sampling_down_factor */
if (policy->cur < policy->max)
policy_dbs->rate_mult = dbs_data->sampling_down_factor;
dbs_freq_increase(policy, policy->max);
} else {
/* Calculate the next frequency proportional to load */
unsigned int freq_next, min_f, max_f;
min_f = policy->cpuinfo.min_freq;
max_f = policy->cpuinfo.max_freq;
freq_next = min_f + load * (max_f - min_f) / 100;
/* No longer fully busy, reset rate_mult */
policy_dbs->rate_mult = 1;
if (od_tuners->powersave_bias)
freq_next = od_ops.powersave_bias_target(policy,
freq_next,
CPUFREQ_RELATION_L);
__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
}
}
static unsigned int od_dbs_update(struct cpufreq_policy *policy)
{
struct policy_dbs_info *policy_dbs = policy->governor_data;
struct dbs_data *dbs_data = policy_dbs->dbs_data;
struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
int sample_type = dbs_info->sample_type;
/* Common NORMAL_SAMPLE setup */
dbs_info->sample_type = OD_NORMAL_SAMPLE;
/*
* OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
* it then.
*/
if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
__cpufreq_driver_target(policy, dbs_info->freq_lo,
CPUFREQ_RELATION_H);
return dbs_info->freq_lo_delay_us;
}
od_update(policy);
if (dbs_info->freq_lo) {
/* Setup SUB_SAMPLE */
dbs_info->sample_type = OD_SUB_SAMPLE;
return dbs_info->freq_hi_delay_us;
}
return dbs_data->sampling_rate * policy_dbs->rate_mult;
}
/************************** sysfs interface ************************/
static struct dbs_governor od_dbs_gov;
static ssize_t store_io_is_busy(struct gov_attr_set *attr_set, const char *buf,
size_t count)
{
struct dbs_data *dbs_data = to_dbs_data(attr_set);
unsigned int input;
int ret;
ret = sscanf(buf, "%u", &input);
if (ret != 1)
return -EINVAL;
dbs_data->io_is_busy = !!input;
/* we need to re-evaluate prev_cpu_idle */
gov_update_cpu_data(dbs_data);
return count;
}
static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
const char *buf, size_t count)
{
struct dbs_data *dbs_data = to_dbs_data(attr_set);
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;
}
dbs_data->up_threshold = input;
return count;
}
static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
const char *buf, size_t count)
{
struct dbs_data *dbs_data = to_dbs_data(attr_set);
struct policy_dbs_info *policy_dbs;
unsigned int input;
int ret;
ret = sscanf(buf, "%u", &input);
if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
return -EINVAL;
dbs_data->sampling_down_factor = input;
/* Reset down sampling multiplier in case it was active */
list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
/*
* Doing this without locking might lead to using different
* rate_mult values in od_update() and od_dbs_update().
*/
mutex_lock(&policy_dbs->update_mutex);
policy_dbs->rate_mult = 1;
mutex_unlock(&policy_dbs->update_mutex);
}
return count;
}
static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
const char *buf, size_t count)
{
struct dbs_data *dbs_data = to_dbs_data(attr_set);
unsigned int input;
int ret;
ret = sscanf(buf, "%u", &input);
if (ret != 1)
return -EINVAL;
if (input > 1)
input = 1;
if (input == dbs_data->ignore_nice_load) { /* nothing to do */
return count;
}
dbs_data->ignore_nice_load = input;
/* we need to re-evaluate prev_cpu_idle */
gov_update_cpu_data(dbs_data);
return count;
}
static ssize_t store_powersave_bias(struct gov_attr_set *attr_set,
const char *buf, size_t count)
{
struct dbs_data *dbs_data = to_dbs_data(attr_set);
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
struct policy_dbs_info *policy_dbs;
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;
list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
ondemand_powersave_bias_init(policy_dbs->policy);
return count;
}
gov_show_one_common(sampling_rate);
gov_show_one_common(up_threshold);
gov_show_one_common(sampling_down_factor);
gov_show_one_common(ignore_nice_load);
gov_show_one_common(io_is_busy);
gov_show_one(od, powersave_bias);
gov_attr_rw(sampling_rate);
gov_attr_rw(io_is_busy);
gov_attr_rw(up_threshold);
gov_attr_rw(sampling_down_factor);
gov_attr_rw(ignore_nice_load);
gov_attr_rw(powersave_bias);
static struct attribute *od_attributes[] = {
&sampling_rate.attr,
&up_threshold.attr,
&sampling_down_factor.attr,
&ignore_nice_load.attr,
&powersave_bias.attr,
&io_is_busy.attr,
NULL
};
/************************** sysfs end ************************/
static struct policy_dbs_info *od_alloc(void)
{
struct od_policy_dbs_info *dbs_info;
dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
return dbs_info ? &dbs_info->policy_dbs : NULL;
}
static void od_free(struct policy_dbs_info *policy_dbs)
{
kfree(to_dbs_info(policy_dbs));
}
static int od_init(struct dbs_data *dbs_data)
{
struct od_dbs_tuners *tuners;
u64 idle_time;
int cpu;
tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
if (!tuners)
return -ENOMEM;
cpu = get_cpu();
idle_time = get_cpu_idle_time_us(cpu, NULL);
put_cpu();
if (idle_time != -1ULL) {
/* Idle micro accounting is supported. Use finer thresholds */
dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
} else {
dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
}
dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
dbs_data->ignore_nice_load = 0;
tuners->powersave_bias = default_powersave_bias;
dbs_data->io_is_busy = should_io_be_busy();
dbs_data->tuners = tuners;
return 0;
}
static void od_exit(struct dbs_data *dbs_data)
{
kfree(dbs_data->tuners);
}
static void od_start(struct cpufreq_policy *policy)
{
struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
dbs_info->sample_type = OD_NORMAL_SAMPLE;
ondemand_powersave_bias_init(policy);
}
static struct od_ops od_ops = {
.powersave_bias_target = generic_powersave_bias_target,
};
static struct dbs_governor od_dbs_gov = {
.gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
.kobj_type = { .default_attrs = od_attributes },
.gov_dbs_update = od_dbs_update,
.alloc = od_alloc,
.free = od_free,
.init = od_init,
.exit = od_exit,
.start = od_start,
};
#define CPU_FREQ_GOV_ONDEMAND (&od_dbs_gov.gov)
static void od_set_powersave_bias(unsigned int powersave_bias)
{
unsigned int cpu;
cpumask_t done;
default_powersave_bias = powersave_bias;
cpumask_clear(&done);
get_online_cpus();
for_each_online_cpu(cpu) {
struct cpufreq_policy *policy;
struct policy_dbs_info *policy_dbs;
struct dbs_data *dbs_data;
struct od_dbs_tuners *od_tuners;
if (cpumask_test_cpu(cpu, &done))
continue;
policy = cpufreq_cpu_get_raw(cpu);
if (!policy || policy->governor != CPU_FREQ_GOV_ONDEMAND)
continue;
policy_dbs = policy->governor_data;
if (!policy_dbs)
continue;
cpumask_or(&done, &done, policy->cpus);
dbs_data = policy_dbs->dbs_data;
od_tuners = dbs_data->tuners;
od_tuners->powersave_bias = default_powersave_bias;
}
put_online_cpus();
}
void od_register_powersave_bias_handler(unsigned int (*f)
(struct cpufreq_policy *, unsigned int, unsigned int),
unsigned int powersave_bias)
{
od_ops.powersave_bias_target = f;
od_set_powersave_bias(powersave_bias);
}
EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
void od_unregister_powersave_bias_handler(void)
{
od_ops.powersave_bias_target = generic_powersave_bias_target;
od_set_powersave_bias(0);
}
EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
static int __init cpufreq_gov_dbs_init(void)
{
return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND);
}
static void __exit cpufreq_gov_dbs_exit(void)
{
cpufreq_unregister_governor(CPU_FREQ_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
struct cpufreq_governor *cpufreq_default_governor(void)
{
return CPU_FREQ_GOV_ONDEMAND;
}
fs_initcall(cpufreq_gov_dbs_init);
#else
module_init(cpufreq_gov_dbs_init);
#endif
module_exit(cpufreq_gov_dbs_exit);