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linux-next/drivers/cpufreq/cpufreq_governor.c
Viresh Kumar 031299b3be cpufreq: governors: Avoid unnecessary per cpu timer interrupts 
Following patch has introduced per cpu timers or works for ondemand and
conservative governors.

	commit 2abfa876f1
	Author: Rickard Andersson <rickard.andersson@stericsson.com>
	Date:   Thu Dec 27 14:55:38 2012 +0000

	    cpufreq: handle SW coordinated CPUs

This causes additional unnecessary interrupts on all cpus when the load is
recently evaluated by any other cpu. i.e. When load is recently evaluated by cpu
x, we don't really need any other cpu to evaluate this load again for the next
sampling_rate time.

Some sort of code is present to avoid that but we are still getting timer
interrupts for all cpus. A good way of avoiding this would be to modify delays
for all cpus (policy->cpus) whenever any cpu has evaluated load.

This patch does this change and some related code cleanup.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-04-01 01:11:35 +02:00

433 lines
11 KiB
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/*
* 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 <asm/cputime.h>
#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/export.h>
#include <linux/kernel_stat.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/tick.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include "cpufreq_governor.h"
static struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy)
{
if (have_governor_per_policy())
return &policy->kobj;
else
return cpufreq_global_kobject;
}
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;
}
static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
{
u64 idle_time;
u64 cur_wall_time;
u64 busy_time;
cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
idle_time = cur_wall_time - busy_time;
if (wall)
*wall = cputime_to_usecs(cur_wall_time);
return cputime_to_usecs(idle_time);
}
u64 get_cpu_idle_time(unsigned int cpu, u64 *wall)
{
u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
if (idle_time == -1ULL)
return get_cpu_idle_time_jiffy(cpu, wall);
else
idle_time += get_cpu_iowait_time_us(cpu, wall);
return idle_time;
}
EXPORT_SYMBOL_GPL(get_cpu_idle_time);
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 max_load = 0;
unsigned int ignore_nice;
unsigned int j;
if (dbs_data->cdata->governor == GOV_ONDEMAND)
ignore_nice = od_tuners->ignore_nice;
else
ignore_nice = cs_tuners->ignore_nice;
policy = cdbs->cur_policy;
/* Get Absolute Load (in terms of freq for ondemand gov) */
for_each_cpu(j, policy->cpus) {
struct cpu_dbs_common_info *j_cdbs;
u64 cur_wall_time, cur_idle_time, cur_iowait_time;
unsigned int idle_time, wall_time, iowait_time;
unsigned int load;
j_cdbs = dbs_data->cdata->get_cpu_cdbs(j);
cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
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 (dbs_data->cdata->governor == GOV_ONDEMAND) {
struct od_cpu_dbs_info_s *od_j_dbs_info =
dbs_data->cdata->get_cpu_dbs_info_s(cpu);
cur_iowait_time = get_cpu_iowait_time_us(j,
&cur_wall_time);
if (cur_iowait_time == -1ULL)
cur_iowait_time = 0;
iowait_time = (unsigned int) (cur_iowait_time -
od_j_dbs_info->prev_cpu_iowait);
od_j_dbs_info->prev_cpu_iowait = cur_iowait_time;
/*
* 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 subtract the
* iowait time from the cpu idle time.
*/
if (od_tuners->io_is_busy && idle_time >= iowait_time)
idle_time -= iowait_time;
}
if (unlikely(!wall_time || wall_time < idle_time))
continue;
load = 100 * (wall_time - idle_time) / wall_time;
if (dbs_data->cdata->governor == GOV_ONDEMAND) {
int freq_avg = __cpufreq_driver_getavg(policy, j);
if (freq_avg <= 0)
freq_avg = policy->cur;
load *= freq_avg;
}
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;
if (!all_cpus) {
__gov_queue_work(smp_processor_id(), dbs_data, delay);
} else {
for_each_cpu(i, policy->cpus)
__gov_queue_work(i, dbs_data, delay);
}
}
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 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) {
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;
rc = cdata->init(dbs_data);
if (rc) {
pr_err("%s: POLICY_INIT: init() failed\n", __func__);
kfree(dbs_data);
return rc;
}
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 (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
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 ((policy->governor->initialized == 1) ||
have_governor_per_policy()) {
sysfs_remove_group(get_governor_parent_kobj(policy),
get_sysfs_attr(dbs_data));
if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
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;
} 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;
od_ops = dbs_data->cdata->gov_ops;
}
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);
j_cdbs->cpu = j;
j_cdbs->cur_policy = policy;
j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
&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);
}
/*
* conservative does not implement micro like ondemand
* governor, thus we are bound to jiffes/HZ
*/
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);
mutex_unlock(&dbs_data->mutex);
break;
case CPUFREQ_GOV_LIMITS:
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);
break;
}
return 0;
}
EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);
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