linux/drivers/cpufreq/cpufreq_conservative.c
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   1/*
   2 *  drivers/cpufreq/cpufreq_conservative.c
   3 *
   4 *  Copyright (C)  2001 Russell King
   5 *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   6 *                      Jun Nakajima <jun.nakajima@intel.com>
   7 *            (C)  2009 Alexander Clouter <alex@digriz.org.uk>
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License version 2 as
  11 * published by the Free Software Foundation.
  12 */
  13
  14#include <linux/cpufreq.h>
  15#include <linux/init.h>
  16#include <linux/kernel.h>
  17#include <linux/kernel_stat.h>
  18#include <linux/kobject.h>
  19#include <linux/module.h>
  20#include <linux/mutex.h>
  21#include <linux/notifier.h>
  22#include <linux/percpu-defs.h>
  23#include <linux/slab.h>
  24#include <linux/sysfs.h>
  25#include <linux/types.h>
  26
  27#include "cpufreq_governor.h"
  28
  29/* Conservative governor macros */
  30#define DEF_FREQUENCY_UP_THRESHOLD              (80)
  31#define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  32#define DEF_FREQUENCY_STEP                      (5)
  33#define DEF_SAMPLING_DOWN_FACTOR                (1)
  34#define MAX_SAMPLING_DOWN_FACTOR                (10)
  35
  36static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
  37
  38static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
  39                                           struct cpufreq_policy *policy)
  40{
  41        unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;
  42
  43        /* max freq cannot be less than 100. But who knows... */
  44        if (unlikely(freq_target == 0))
  45                freq_target = DEF_FREQUENCY_STEP;
  46
  47        return freq_target;
  48}
  49
  50/*
  51 * Every sampling_rate, we check, if current idle time is less than 20%
  52 * (default), then we try to increase frequency. Every sampling_rate *
  53 * sampling_down_factor, we check, if current idle time is more than 80%
  54 * (default), then we try to decrease frequency
  55 *
  56 * Any frequency increase takes it to the maximum frequency. Frequency reduction
  57 * happens at minimum steps of 5% (default) of maximum frequency
  58 */
  59static void cs_check_cpu(int cpu, unsigned int load)
  60{
  61        struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
  62        struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
  63        struct dbs_data *dbs_data = policy->governor_data;
  64        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  65
  66        /*
  67         * break out if we 'cannot' reduce the speed as the user might
  68         * want freq_step to be zero
  69         */
  70        if (cs_tuners->freq_step == 0)
  71                return;
  72
  73        /* Check for frequency increase */
  74        if (load > cs_tuners->up_threshold) {
  75                dbs_info->down_skip = 0;
  76
  77                /* if we are already at full speed then break out early */
  78                if (dbs_info->requested_freq == policy->max)
  79                        return;
  80
  81                dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
  82                if (dbs_info->requested_freq > policy->max)
  83                        dbs_info->requested_freq = policy->max;
  84
  85                __cpufreq_driver_target(policy, dbs_info->requested_freq,
  86                        CPUFREQ_RELATION_H);
  87                return;
  88        }
  89
  90        /* if sampling_down_factor is active break out early */
  91        if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
  92                return;
  93        dbs_info->down_skip = 0;
  94
  95        /* Check for frequency decrease */
  96        if (load < cs_tuners->down_threshold) {
  97                /*
  98                 * if we cannot reduce the frequency anymore, break out early
  99                 */
 100                if (policy->cur == policy->min)
 101                        return;
 102
 103                dbs_info->requested_freq -= get_freq_target(cs_tuners, policy);
 104                if (dbs_info->requested_freq < policy->min)
 105                        dbs_info->requested_freq = policy->min;
 106
 107                __cpufreq_driver_target(policy, dbs_info->requested_freq,
 108                                CPUFREQ_RELATION_L);
 109                return;
 110        }
 111}
 112
 113static void cs_dbs_timer(struct work_struct *work)
 114{
 115        struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
 116                        struct cs_cpu_dbs_info_s, cdbs.work.work);
 117        unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 118        struct cs_cpu_dbs_info_s *core_dbs_info = &per_cpu(cs_cpu_dbs_info,
 119                        cpu);
 120        struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data;
 121        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 122        int delay = delay_for_sampling_rate(cs_tuners->sampling_rate);
 123        bool modify_all = true;
 124
 125        mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 126        if (!need_load_eval(&core_dbs_info->cdbs, cs_tuners->sampling_rate))
 127                modify_all = false;
 128        else
 129                dbs_check_cpu(dbs_data, cpu);
 130
 131        gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all);
 132        mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 133}
 134
 135static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 136                void *data)
 137{
 138        struct cpufreq_freqs *freq = data;
 139        struct cs_cpu_dbs_info_s *dbs_info =
 140                                        &per_cpu(cs_cpu_dbs_info, freq->cpu);
 141        struct cpufreq_policy *policy;
 142
 143        if (!dbs_info->enable)
 144                return 0;
 145
 146        policy = dbs_info->cdbs.cur_policy;
 147
 148        /*
 149         * we only care if our internally tracked freq moves outside the 'valid'
 150         * ranges of frequency available to us otherwise we do not change it
 151        */
 152        if (dbs_info->requested_freq > policy->max
 153                        || dbs_info->requested_freq < policy->min)
 154                dbs_info->requested_freq = freq->new;
 155
 156        return 0;
 157}
 158
 159/************************** sysfs interface ************************/
 160static struct common_dbs_data cs_dbs_cdata;
 161
 162static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 163                const char *buf, size_t count)
 164{
 165        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 166        unsigned int input;
 167        int ret;
 168        ret = sscanf(buf, "%u", &input);
 169
 170        if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 171                return -EINVAL;
 172
 173        cs_tuners->sampling_down_factor = input;
 174        return count;
 175}
 176
 177static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 178                size_t count)
 179{
 180        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 181        unsigned int input;
 182        int ret;
 183        ret = sscanf(buf, "%u", &input);
 184
 185        if (ret != 1)
 186                return -EINVAL;
 187
 188        cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate);
 189        return count;
 190}
 191
 192static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 193                size_t count)
 194{
 195        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 196        unsigned int input;
 197        int ret;
 198        ret = sscanf(buf, "%u", &input);
 199
 200        if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 201                return -EINVAL;
 202
 203        cs_tuners->up_threshold = input;
 204        return count;
 205}
 206
 207static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 208                size_t count)
 209{
 210        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 211        unsigned int input;
 212        int ret;
 213        ret = sscanf(buf, "%u", &input);
 214
 215        /* cannot be lower than 11 otherwise freq will not fall */
 216        if (ret != 1 || input < 11 || input > 100 ||
 217                        input >= cs_tuners->up_threshold)
 218                return -EINVAL;
 219
 220        cs_tuners->down_threshold = input;
 221        return count;
 222}
 223
 224static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 225                const char *buf, size_t count)
 226{
 227        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 228        unsigned int input, j;
 229        int ret;
 230
 231        ret = sscanf(buf, "%u", &input);
 232        if (ret != 1)
 233                return -EINVAL;
 234
 235        if (input > 1)
 236                input = 1;
 237
 238        if (input == cs_tuners->ignore_nice_load) /* nothing to do */
 239                return count;
 240
 241        cs_tuners->ignore_nice_load = input;
 242
 243        /* we need to re-evaluate prev_cpu_idle */
 244        for_each_online_cpu(j) {
 245                struct cs_cpu_dbs_info_s *dbs_info;
 246                dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 247                dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 248                                        &dbs_info->cdbs.prev_cpu_wall, 0);
 249                if (cs_tuners->ignore_nice_load)
 250                        dbs_info->cdbs.prev_cpu_nice =
 251                                kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 252        }
 253        return count;
 254}
 255
 256static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
 257                size_t count)
 258{
 259        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 260        unsigned int input;
 261        int ret;
 262        ret = sscanf(buf, "%u", &input);
 263
 264        if (ret != 1)
 265                return -EINVAL;
 266
 267        if (input > 100)
 268                input = 100;
 269
 270        /*
 271         * no need to test here if freq_step is zero as the user might actually
 272         * want this, they would be crazy though :)
 273         */
 274        cs_tuners->freq_step = input;
 275        return count;
 276}
 277
 278show_store_one(cs, sampling_rate);
 279show_store_one(cs, sampling_down_factor);
 280show_store_one(cs, up_threshold);
 281show_store_one(cs, down_threshold);
 282show_store_one(cs, ignore_nice_load);
 283show_store_one(cs, freq_step);
 284declare_show_sampling_rate_min(cs);
 285
 286gov_sys_pol_attr_rw(sampling_rate);
 287gov_sys_pol_attr_rw(sampling_down_factor);
 288gov_sys_pol_attr_rw(up_threshold);
 289gov_sys_pol_attr_rw(down_threshold);
 290gov_sys_pol_attr_rw(ignore_nice_load);
 291gov_sys_pol_attr_rw(freq_step);
 292gov_sys_pol_attr_ro(sampling_rate_min);
 293
 294static struct attribute *dbs_attributes_gov_sys[] = {
 295        &sampling_rate_min_gov_sys.attr,
 296        &sampling_rate_gov_sys.attr,
 297        &sampling_down_factor_gov_sys.attr,
 298        &up_threshold_gov_sys.attr,
 299        &down_threshold_gov_sys.attr,
 300        &ignore_nice_load_gov_sys.attr,
 301        &freq_step_gov_sys.attr,
 302        NULL
 303};
 304
 305static struct attribute_group cs_attr_group_gov_sys = {
 306        .attrs = dbs_attributes_gov_sys,
 307        .name = "conservative",
 308};
 309
 310static struct attribute *dbs_attributes_gov_pol[] = {
 311        &sampling_rate_min_gov_pol.attr,
 312        &sampling_rate_gov_pol.attr,
 313        &sampling_down_factor_gov_pol.attr,
 314        &up_threshold_gov_pol.attr,
 315        &down_threshold_gov_pol.attr,
 316        &ignore_nice_load_gov_pol.attr,
 317        &freq_step_gov_pol.attr,
 318        NULL
 319};
 320
 321static struct attribute_group cs_attr_group_gov_pol = {
 322        .attrs = dbs_attributes_gov_pol,
 323        .name = "conservative",
 324};
 325
 326/************************** sysfs end ************************/
 327
 328static int cs_init(struct dbs_data *dbs_data)
 329{
 330        struct cs_dbs_tuners *tuners;
 331
 332        tuners = kzalloc(sizeof(struct cs_dbs_tuners), GFP_KERNEL);
 333        if (!tuners) {
 334                pr_err("%s: kzalloc failed\n", __func__);
 335                return -ENOMEM;
 336        }
 337
 338        tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 339        tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 340        tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 341        tuners->ignore_nice_load = 0;
 342        tuners->freq_step = DEF_FREQUENCY_STEP;
 343
 344        dbs_data->tuners = tuners;
 345        dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 346                jiffies_to_usecs(10);
 347        mutex_init(&dbs_data->mutex);
 348        return 0;
 349}
 350
 351static void cs_exit(struct dbs_data *dbs_data)
 352{
 353        kfree(dbs_data->tuners);
 354}
 355
 356define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 357
 358static struct notifier_block cs_cpufreq_notifier_block = {
 359        .notifier_call = dbs_cpufreq_notifier,
 360};
 361
 362static struct cs_ops cs_ops = {
 363        .notifier_block = &cs_cpufreq_notifier_block,
 364};
 365
 366static struct common_dbs_data cs_dbs_cdata = {
 367        .governor = GOV_CONSERVATIVE,
 368        .attr_group_gov_sys = &cs_attr_group_gov_sys,
 369        .attr_group_gov_pol = &cs_attr_group_gov_pol,
 370        .get_cpu_cdbs = get_cpu_cdbs,
 371        .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 372        .gov_dbs_timer = cs_dbs_timer,
 373        .gov_check_cpu = cs_check_cpu,
 374        .gov_ops = &cs_ops,
 375        .init = cs_init,
 376        .exit = cs_exit,
 377};
 378
 379static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 380                                   unsigned int event)
 381{
 382        return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event);
 383}
 384
 385#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 386static
 387#endif
 388struct cpufreq_governor cpufreq_gov_conservative = {
 389        .name                   = "conservative",
 390        .governor               = cs_cpufreq_governor_dbs,
 391        .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 392        .owner                  = THIS_MODULE,
 393};
 394
 395static int __init cpufreq_gov_dbs_init(void)
 396{
 397        return cpufreq_register_governor(&cpufreq_gov_conservative);
 398}
 399
 400static void __exit cpufreq_gov_dbs_exit(void)
 401{
 402        cpufreq_unregister_governor(&cpufreq_gov_conservative);
 403}
 404
 405MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 406MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 407                "Low Latency Frequency Transition capable processors "
 408                "optimised for use in a battery environment");
 409MODULE_LICENSE("GPL");
 410
 411#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 412fs_initcall(cpufreq_gov_dbs_init);
 413#else
 414module_init(cpufreq_gov_dbs_init);
 415#endif
 416module_exit(cpufreq_gov_dbs_exit);
 417
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