https://github.com/torvalds/linux
Tip revision: f22e6e847115abc3a0e2ad7bb18d243d42275af1 authored by Linus Torvalds on 06 April 2015, 22:39:45 UTC
Linux 4.0-rc7
Linux 4.0-rc7
Tip revision: f22e6e8
cpufreq_governor.c
/*
* drivers/cpufreq/cpufreq_governor.c
*
* CPUFREQ governors common code
*
* Copyright (C) 2001 Russell King
* (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
* (C) 2003 Jun Nakajima <jun.nakajima@intel.com>
* (C) 2009 Alexander Clouter <alex@digriz.org.uk>
* (c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
*
* 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/export.h>
#include <linux/kernel_stat.h>
#include <linux/slab.h>
#include "cpufreq_governor.h"
static struct attribute_group *get_sysfs_attr(struct dbs_data *dbs_data)
{
if (have_governor_per_policy())
return dbs_data->cdata->attr_group_gov_pol;
else
return dbs_data->cdata->attr_group_gov_sys;
}
void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
{
struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
struct cpufreq_policy *policy;
unsigned int sampling_rate;
unsigned int max_load = 0;
unsigned int ignore_nice;
unsigned int j;
if (dbs_data->cdata->governor == GOV_ONDEMAND) {
struct od_cpu_dbs_info_s *od_dbs_info =
dbs_data->cdata->get_cpu_dbs_info_s(cpu);
/*
* Sometimes, the ondemand governor uses an additional
* multiplier to give long delays. So apply this multiplier to
* the 'sampling_rate', so as to keep the wake-up-from-idle
* detection logic a bit conservative.
*/
sampling_rate = od_tuners->sampling_rate;
sampling_rate *= od_dbs_info->rate_mult;
ignore_nice = od_tuners->ignore_nice_load;
} else {
sampling_rate = cs_tuners->sampling_rate;
ignore_nice = cs_tuners->ignore_nice_load;
}
policy = cdbs->cur_policy;
/* Get Absolute Load */
for_each_cpu(j, policy->cpus) {
struct cpu_dbs_common_info *j_cdbs;
u64 cur_wall_time, cur_idle_time;
unsigned int idle_time, wall_time;
unsigned int load;
int io_busy = 0;
j_cdbs = dbs_data->cdata->get_cpu_cdbs(j);
/*
* For the purpose of ondemand, waiting for disk IO is
* an indication that you're performance critical, and
* not that the system is actually idle. So do not add
* the iowait time to the cpu idle time.
*/
if (dbs_data->cdata->governor == GOV_ONDEMAND)
io_busy = od_tuners->io_is_busy;
cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy);
wall_time = (unsigned int)
(cur_wall_time - j_cdbs->prev_cpu_wall);
j_cdbs->prev_cpu_wall = cur_wall_time;
idle_time = (unsigned int)
(cur_idle_time - j_cdbs->prev_cpu_idle);
j_cdbs->prev_cpu_idle = cur_idle_time;
if (ignore_nice) {
u64 cur_nice;
unsigned long cur_nice_jiffies;
cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
cdbs->prev_cpu_nice;
/*
* Assumption: nice time between sampling periods will
* be less than 2^32 jiffies for 32 bit sys
*/
cur_nice_jiffies = (unsigned long)
cputime64_to_jiffies64(cur_nice);
cdbs->prev_cpu_nice =
kcpustat_cpu(j).cpustat[CPUTIME_NICE];
idle_time += jiffies_to_usecs(cur_nice_jiffies);
}
if (unlikely(!wall_time || wall_time < idle_time))
continue;
/*
* If the CPU had gone completely idle, and a task just woke up
* on this CPU now, it would be unfair to calculate 'load' the
* usual way for this elapsed time-window, because it will show
* near-zero load, irrespective of how CPU intensive that task
* actually is. This is undesirable for latency-sensitive bursty
* workloads.
*
* To avoid this, we reuse the 'load' from the previous
* time-window and give this task a chance to start with a
* reasonably high CPU frequency. (However, we shouldn't over-do
* this copy, lest we get stuck at a high load (high frequency)
* for too long, even when the current system load has actually
* dropped down. So we perform the copy only once, upon the
* first wake-up from idle.)
*
* Detecting this situation is easy: the governor's deferrable
* timer would not have fired during CPU-idle periods. Hence
* an unusually large 'wall_time' (as compared to the sampling
* rate) indicates this scenario.
*
* prev_load can be zero in two cases and we must recalculate it
* for both cases:
* - during long idle intervals
* - explicitly set to zero
*/
if (unlikely(wall_time > (2 * sampling_rate) &&
j_cdbs->prev_load)) {
load = j_cdbs->prev_load;
/*
* Perform a destructive copy, to ensure that we copy
* the previous load only once, upon the first wake-up
* from idle.
*/
j_cdbs->prev_load = 0;
} else {
load = 100 * (wall_time - idle_time) / wall_time;
j_cdbs->prev_load = load;
}
if (load > max_load)
max_load = load;
}
dbs_data->cdata->gov_check_cpu(cpu, max_load);
}
EXPORT_SYMBOL_GPL(dbs_check_cpu);
static inline void __gov_queue_work(int cpu, struct dbs_data *dbs_data,
unsigned int delay)
{
struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
mod_delayed_work_on(cpu, system_wq, &cdbs->work, delay);
}
void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
unsigned int delay, bool all_cpus)
{
int i;
mutex_lock(&cpufreq_governor_lock);
if (!policy->governor_enabled)
goto out_unlock;
if (!all_cpus) {
/*
* Use raw_smp_processor_id() to avoid preemptible warnings.
* We know that this is only called with all_cpus == false from
* works that have been queued with *_work_on() functions and
* those works are canceled during CPU_DOWN_PREPARE so they
* can't possibly run on any other CPU.
*/
__gov_queue_work(raw_smp_processor_id(), dbs_data, delay);
} else {
for_each_cpu(i, policy->cpus)
__gov_queue_work(i, dbs_data, delay);
}
out_unlock:
mutex_unlock(&cpufreq_governor_lock);
}
EXPORT_SYMBOL_GPL(gov_queue_work);
static inline void gov_cancel_work(struct dbs_data *dbs_data,
struct cpufreq_policy *policy)
{
struct cpu_dbs_common_info *cdbs;
int i;
for_each_cpu(i, policy->cpus) {
cdbs = dbs_data->cdata->get_cpu_cdbs(i);
cancel_delayed_work_sync(&cdbs->work);
}
}
/* Will return if we need to evaluate cpu load again or not */
bool need_load_eval(struct cpu_dbs_common_info *cdbs,
unsigned int sampling_rate)
{
if (policy_is_shared(cdbs->cur_policy)) {
ktime_t time_now = ktime_get();
s64 delta_us = ktime_us_delta(time_now, cdbs->time_stamp);
/* Do nothing if we recently have sampled */
if (delta_us < (s64)(sampling_rate / 2))
return false;
else
cdbs->time_stamp = time_now;
}
return true;
}
EXPORT_SYMBOL_GPL(need_load_eval);
static void set_sampling_rate(struct dbs_data *dbs_data,
unsigned int sampling_rate)
{
if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
cs_tuners->sampling_rate = sampling_rate;
} else {
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
od_tuners->sampling_rate = sampling_rate;
}
}
int cpufreq_governor_dbs(struct cpufreq_policy *policy,
struct common_dbs_data *cdata, unsigned int event)
{
struct dbs_data *dbs_data;
struct od_cpu_dbs_info_s *od_dbs_info = NULL;
struct cs_cpu_dbs_info_s *cs_dbs_info = NULL;
struct od_ops *od_ops = NULL;
struct od_dbs_tuners *od_tuners = NULL;
struct cs_dbs_tuners *cs_tuners = NULL;
struct cpu_dbs_common_info *cpu_cdbs;
unsigned int sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;
int io_busy = 0;
int rc;
if (have_governor_per_policy())
dbs_data = policy->governor_data;
else
dbs_data = cdata->gdbs_data;
WARN_ON(!dbs_data && (event != CPUFREQ_GOV_POLICY_INIT));
switch (event) {
case CPUFREQ_GOV_POLICY_INIT:
if (have_governor_per_policy()) {
WARN_ON(dbs_data);
} else if (dbs_data) {
dbs_data->usage_count++;
policy->governor_data = dbs_data;
return 0;
}
dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
if (!dbs_data) {
pr_err("%s: POLICY_INIT: kzalloc failed\n", __func__);
return -ENOMEM;
}
dbs_data->cdata = cdata;
dbs_data->usage_count = 1;
rc = cdata->init(dbs_data);
if (rc) {
pr_err("%s: POLICY_INIT: init() failed\n", __func__);
kfree(dbs_data);
return rc;
}
if (!have_governor_per_policy())
WARN_ON(cpufreq_get_global_kobject());
rc = sysfs_create_group(get_governor_parent_kobj(policy),
get_sysfs_attr(dbs_data));
if (rc) {
cdata->exit(dbs_data);
kfree(dbs_data);
return rc;
}
policy->governor_data = dbs_data;
/* policy latency is in ns. Convert it to us first */
latency = policy->cpuinfo.transition_latency / 1000;
if (latency == 0)
latency = 1;
/* Bring kernel and HW constraints together */
dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
MIN_LATENCY_MULTIPLIER * latency);
set_sampling_rate(dbs_data, max(dbs_data->min_sampling_rate,
latency * LATENCY_MULTIPLIER));
if ((cdata->governor == GOV_CONSERVATIVE) &&
(!policy->governor->initialized)) {
struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
cpufreq_register_notifier(cs_ops->notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
}
if (!have_governor_per_policy())
cdata->gdbs_data = dbs_data;
return 0;
case CPUFREQ_GOV_POLICY_EXIT:
if (!--dbs_data->usage_count) {
sysfs_remove_group(get_governor_parent_kobj(policy),
get_sysfs_attr(dbs_data));
if (!have_governor_per_policy())
cpufreq_put_global_kobject();
if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) &&
(policy->governor->initialized == 1)) {
struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
cpufreq_unregister_notifier(cs_ops->notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
}
cdata->exit(dbs_data);
kfree(dbs_data);
cdata->gdbs_data = NULL;
}
policy->governor_data = NULL;
return 0;
}
cpu_cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
cs_tuners = dbs_data->tuners;
cs_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
sampling_rate = cs_tuners->sampling_rate;
ignore_nice = cs_tuners->ignore_nice_load;
} else {
od_tuners = dbs_data->tuners;
od_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
sampling_rate = od_tuners->sampling_rate;
ignore_nice = od_tuners->ignore_nice_load;
od_ops = dbs_data->cdata->gov_ops;
io_busy = od_tuners->io_is_busy;
}
switch (event) {
case CPUFREQ_GOV_START:
if (!policy->cur)
return -EINVAL;
mutex_lock(&dbs_data->mutex);
for_each_cpu(j, policy->cpus) {
struct cpu_dbs_common_info *j_cdbs =
dbs_data->cdata->get_cpu_cdbs(j);
unsigned int prev_load;
j_cdbs->cpu = j;
j_cdbs->cur_policy = policy;
j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
&j_cdbs->prev_cpu_wall, io_busy);
prev_load = (unsigned int)
(j_cdbs->prev_cpu_wall - j_cdbs->prev_cpu_idle);
j_cdbs->prev_load = 100 * prev_load /
(unsigned int) j_cdbs->prev_cpu_wall;
if (ignore_nice)
j_cdbs->prev_cpu_nice =
kcpustat_cpu(j).cpustat[CPUTIME_NICE];
mutex_init(&j_cdbs->timer_mutex);
INIT_DEFERRABLE_WORK(&j_cdbs->work,
dbs_data->cdata->gov_dbs_timer);
}
if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
cs_dbs_info->down_skip = 0;
cs_dbs_info->enable = 1;
cs_dbs_info->requested_freq = policy->cur;
} else {
od_dbs_info->rate_mult = 1;
od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
od_ops->powersave_bias_init_cpu(cpu);
}
mutex_unlock(&dbs_data->mutex);
/* Initiate timer time stamp */
cpu_cdbs->time_stamp = ktime_get();
gov_queue_work(dbs_data, policy,
delay_for_sampling_rate(sampling_rate), true);
break;
case CPUFREQ_GOV_STOP:
if (dbs_data->cdata->governor == GOV_CONSERVATIVE)
cs_dbs_info->enable = 0;
gov_cancel_work(dbs_data, policy);
mutex_lock(&dbs_data->mutex);
mutex_destroy(&cpu_cdbs->timer_mutex);
cpu_cdbs->cur_policy = NULL;
mutex_unlock(&dbs_data->mutex);
break;
case CPUFREQ_GOV_LIMITS:
mutex_lock(&dbs_data->mutex);
if (!cpu_cdbs->cur_policy) {
mutex_unlock(&dbs_data->mutex);
break;
}
mutex_lock(&cpu_cdbs->timer_mutex);
if (policy->max < cpu_cdbs->cur_policy->cur)
__cpufreq_driver_target(cpu_cdbs->cur_policy,
policy->max, CPUFREQ_RELATION_H);
else if (policy->min > cpu_cdbs->cur_policy->cur)
__cpufreq_driver_target(cpu_cdbs->cur_policy,
policy->min, CPUFREQ_RELATION_L);
dbs_check_cpu(dbs_data, cpu);
mutex_unlock(&cpu_cdbs->timer_mutex);
mutex_unlock(&dbs_data->mutex);
break;
}
return 0;
}
EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);