drivers/cpuquiet/governors/balanced.c

   1 /*
   2  * Copyright (c) 2012 NVIDIA CORPORATION.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  16  *
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/cpuquiet.h>
  21 #include <linux/cpumask.h>
  22 #include <linux/module.h>
  23 #include <linux/cpufreq.h>
  24 #include <linux/pm_qos.h>
  25 #include <linux/jiffies.h>
  26 #include <linux/slab.h>
  27 #include <linux/cpu.h>
  28 #include <linux/sched.h>
  29 #include <linux/tick.h>
  30 #include <asm/cputime.h>
  31
  32 #define CPUNAMELEN 8
  33
  34 typedef enum {
  35         CPU_SPEED_BALANCED,
  36         CPU_SPEED_BIASED,
  37         CPU_SPEED_SKEWED,
  38 } CPU_SPEED_BALANCE;
  39
  40 typedef enum {
  41         IDLE,
  42         DOWN,
  43         UP,
  44 } BALANCED_STATE;
  45
  46 struct idle_info {
  47         u64 idle_last;
  48         u64 last_timestamp;
  49         u64 idle_current;
  50         u64 timestamp;
  51 };
  52
  53 static DEFINE_PER_CPU(struct idle_info, idleinfo);
  54 static DEFINE_PER_CPU(unsigned int, cpu_load);
  55
  56 static struct timer_list load_timer;
  57 static bool load_timer_active;
  58
  59 /* configurable parameters */
  60 static unsigned int  balance_level = 60;
  61 static unsigned int  idle_bottom_freq;
  62 static unsigned int  idle_top_freq;
  63 static unsigned long up_delay;
  64 static unsigned long down_delay;
  65 static unsigned long last_change_time;
  66 static unsigned int  load_sample_rate = 20; /* msec */
  67 static struct workqueue_struct *balanced_wq;
  68 static struct delayed_work balanced_work;
  69 static BALANCED_STATE balanced_state;
  70 static struct kobject *balanced_kobject;
  71
  72 static void calculate_load_timer(unsigned long data)
  73 {
  74         int i;
  75         u64 idle_time, elapsed_time;
  76
  77         if (!load_timer_active)
  78                 return;
  79
  80         for_each_online_cpu(i) {
  81                 struct idle_info *iinfo = &per_cpu(idleinfo, i);
  82                 unsigned int *load = &per_cpu(cpu_load, i);
  83
  84                 iinfo->idle_last = iinfo->idle_current;
  85                 iinfo->last_timestamp = iinfo->timestamp;
  86                 iinfo->idle_current =
  87                         get_cpu_idle_time_us(i, &iinfo->timestamp);
  88                 elapsed_time = iinfo->timestamp - iinfo->last_timestamp;
  89
  90                 idle_time = iinfo->idle_current - iinfo->idle_last;
  91                 idle_time *= 100;
  92                 do_div(idle_time, elapsed_time);
  93                 *load = 100 - idle_time;
  94         }
  95         mod_timer(&load_timer, jiffies + msecs_to_jiffies(load_sample_rate));
  96 }
  97
  98 static void start_load_timer(void)
  99 {
 100         int i;
 101
 102         if (load_timer_active)
 103                 return;
 104
 105         load_timer_active = true;
 106
 107         for_each_online_cpu(i) {
 108                 struct idle_info *iinfo = &per_cpu(idleinfo, i);
 109
 110                 iinfo->idle_current =
 111                         get_cpu_idle_time_us(i, &iinfo->timestamp);
 112         }
 113         mod_timer(&load_timer, jiffies + msecs_to_jiffies(100));
 114 }
 115
 116 static void stop_load_timer(void)
 117 {
 118         if (!load_timer_active)
 119                 return;
 120
 121         load_timer_active = false;
 122         del_timer(&load_timer);
 123 }
 124
 125 static unsigned int get_slowest_cpu_n(void)
 126 {
 127         unsigned int cpu = nr_cpu_ids;
 128         unsigned long minload = ULONG_MAX;
 129         int i;
 130
 131         for_each_online_cpu(i) {
 132                 unsigned int *load = &per_cpu(cpu_load, i);
 133
 134                 if ((i > 0) && (minload > *load)) {
 135                         cpu = i;
 136                         minload = *load;
 137                 }
 138         }
 139
 140         return cpu;
 141 }
 142
 143 static unsigned int cpu_highest_speed(void)
 144 {
 145         unsigned int maxload = 0;
 146         int i;
 147
 148         for_each_online_cpu(i) {
 149                 unsigned int *load = &per_cpu(cpu_load, i);
 150
 151                 maxload = max(maxload, *load);
 152         }
 153
 154         return maxload;
 155 }
 156
 157 static unsigned int count_slow_cpus(unsigned int limit)
 158 {
 159         unsigned int cnt = 0;
 160         int i;
 161
 162         for_each_online_cpu(i) {
 163                 unsigned int *load = &per_cpu(cpu_load, i);
 164
 165                 if (*load <= limit)
 166                         cnt++;
 167         }
 168
 169         return cnt;
 170 }
 171
 172 #define NR_FSHIFT       2
 173 static unsigned int nr_run_thresholds[] = {
 174 /*      1,  2,  3,  4 - on-line cpus target */
 175         5,  9, 10, UINT_MAX /* avg run threads * 4 (e.g., 9 = 2.25 threads) */
 176 };
 177 static unsigned int nr_run_hysteresis = 2;      /* 0.5 thread */
 178 static unsigned int nr_run_last;
 179
 180 static CPU_SPEED_BALANCE balanced_speed_balance(void)
 181 {
 182         unsigned long highest_speed = cpu_highest_speed();
 183         unsigned long balanced_speed = highest_speed * balance_level / 100;
 184         unsigned long skewed_speed = balanced_speed / 2;
 185         unsigned int nr_cpus = num_online_cpus();
 186         unsigned int max_cpus = pm_qos_request(PM_QOS_MAX_ONLINE_CPUS) ? : 4;
 187         unsigned int avg_nr_run = avg_nr_running();
 188         unsigned int nr_run;
 189
 190         /* balanced: freq targets for all CPUs are above 50% of highest speed
 191            biased: freq target for at least one CPU is below 50% threshold
 192            skewed: freq targets for at least 2 CPUs are below 25% threshold */
 193         for (nr_run = 1; nr_run < ARRAY_SIZE(nr_run_thresholds); nr_run++) {
 194                 unsigned int nr_threshold = nr_run_thresholds[nr_run - 1];
 195                 if (nr_run_last <= nr_run)
 196                         nr_threshold += nr_run_hysteresis;
 197                 if (avg_nr_run <= (nr_threshold << (FSHIFT - NR_FSHIFT)))
 198                         break;
 199         }
 200         nr_run_last = nr_run;
 201
 202         if (count_slow_cpus(skewed_speed) >= 2 || nr_cpus > max_cpus ||
 203                 nr_run < nr_cpus)
 204                 return CPU_SPEED_SKEWED;
 205
 206         if (count_slow_cpus(balanced_speed) >= 1 || nr_cpus == max_cpus ||
 207                 nr_run <= nr_cpus)
 208                 return CPU_SPEED_BIASED;
 209
 210         return CPU_SPEED_BALANCED;
 211 }
 212
 213 static void balanced_work_func(struct work_struct *work)
 214 {
 215         bool up = false;
 216         unsigned int cpu = nr_cpu_ids;
 217         unsigned long now = jiffies;
 218
 219         CPU_SPEED_BALANCE balance;
 220
 221         switch (balanced_state) {
 222         case IDLE:
 223                 break;
 224         case DOWN:
 225                 cpu = get_slowest_cpu_n();
 226                 if (cpu < nr_cpu_ids) {
 227                         up = false;
 228                         queue_delayed_work(balanced_wq,
 229                                                  &balanced_work, up_delay);
 230                 } else
 231                         stop_load_timer();
 232                 break;
 233         case UP:
 234                 balance = balanced_speed_balance();
 235                 switch (balance) {
 236
 237                 /* cpu speed is up and balanced - one more on-line */
 238                 case CPU_SPEED_BALANCED:
 239                         cpu = cpumask_next_zero(0, cpu_online_mask);
 240                         if (cpu < nr_cpu_ids)
 241                                 up = true;
 242                         break;
 243                 /* cpu speed is up, but skewed - remove one core */
 244                 case CPU_SPEED_SKEWED:
 245                         cpu = get_slowest_cpu_n();
 246                         if (cpu < nr_cpu_ids)
 247                                 up = false;
 248                         break;
 249                 /* cpu speed is up, but under-utilized - do nothing */
 250                 case CPU_SPEED_BIASED:
 251                 default:
 252                         break;
 253                 }
 254                 queue_delayed_work(
 255                         balanced_wq, &balanced_work, up_delay);
 256                 break;
 257         default:
 258                 pr_err("%s: invalid cpuquiet balanced governor state %d\n",
 259                        __func__, balanced_state);
 260         }
 261
 262         if (!up && ((now - last_change_time) < down_delay))
 263                 cpu = nr_cpu_ids;
 264
 265         if (cpu < nr_cpu_ids) {
 266                 last_change_time = now;
 267                 if (up)
 268                         cpuquiet_wake_cpu(cpu);
 269                 else
 270                         cpuquiet_quiesence_cpu(cpu);
 271         }
 272 }
 273
 274 static int balanced_cpufreq_transition(struct notifier_block *nb,
 275         unsigned long state, void *data)
 276 {
 277         struct cpufreq_freqs *freqs = data;
 278         unsigned long cpu_freq;
 279
 280         if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE) {
 281                 cpu_freq = freqs->new;
 282
 283                 switch (balanced_state) {
 284                 case IDLE:
 285                         if (cpu_freq >= idle_top_freq) {
 286                                 balanced_state = UP;
 287                                 queue_delayed_work(
 288                                         balanced_wq, &balanced_work, up_delay);
 289                                 start_load_timer();
 290                         } else if (cpu_freq <= idle_bottom_freq) {
 291                                 balanced_state = DOWN;
 292                                 queue_delayed_work(
 293                                         balanced_wq, &balanced_work,
 294                                         down_delay);
 295                                 start_load_timer();
 296                         }
 297                         break;
 298                 case DOWN:
 299                         if (cpu_freq >= idle_top_freq) {
 300                                 balanced_state = UP;
 301                                 queue_delayed_work(
 302                                         balanced_wq, &balanced_work, up_delay);
 303                                 start_load_timer();
 304                         }
 305                         break;
 306                 case UP:
 307                         if (cpu_freq <= idle_bottom_freq) {
 308                                 balanced_state = DOWN;
 309                                 queue_delayed_work(balanced_wq,
 310                                         &balanced_work, up_delay);
 311                                 start_load_timer();
 312                         }
 313                         break;
 314                 default:
 315                         pr_err("%s: invalid cpuquiet balanced governor "
 316                                 "state %d\n", __func__, balanced_state);
 317                 }
 318         }
 319
 320         return NOTIFY_OK;
 321 }
 322
 323 static struct notifier_block balanced_cpufreq_nb = {
 324         .notifier_call = balanced_cpufreq_transition,
 325 };
 326
 327 static void delay_callback(struct cpuquiet_attribute *attr)
 328 {
 329         unsigned long val;
 330
 331         if (attr) {
 332                 val = (*((unsigned long *)(attr->param)));
 333                 (*((unsigned long *)(attr->param))) = msecs_to_jiffies(val);
 334         }
 335 }
 336
 337 CPQ_BASIC_ATTRIBUTE(balance_level, 0644, uint);
 338 CPQ_BASIC_ATTRIBUTE(idle_bottom_freq, 0644, uint);
 339 CPQ_BASIC_ATTRIBUTE(idle_top_freq, 0644, uint);
 340 CPQ_BASIC_ATTRIBUTE(load_sample_rate, 0644, uint);
 341 CPQ_ATTRIBUTE(up_delay, 0644, ulong, delay_callback);
 342 CPQ_ATTRIBUTE(down_delay, 0644, ulong, delay_callback);
 343
 344 static struct attribute *balanced_attributes[] = {
 345         &balance_level_attr.attr,
 346         &idle_bottom_freq_attr.attr,
 347         &idle_top_freq_attr.attr,
 348         &up_delay_attr.attr,
 349         &down_delay_attr.attr,
 350         &load_sample_rate_attr.attr,
 351         NULL,
 352 };
 353
 354 static const struct sysfs_ops balanced_sysfs_ops = {
 355         .show = cpuquiet_auto_sysfs_show,
 356         .store = cpuquiet_auto_sysfs_store,
 357 };
 358
 359 static struct kobj_type ktype_balanced = {
 360         .sysfs_ops = &balanced_sysfs_ops,
 361         .default_attrs = balanced_attributes,
 362 };
 363
 364 static int balanced_sysfs(void)
 365 {
 366         int err;
 367
 368         balanced_kobject = kzalloc(sizeof(*balanced_kobject),
 369                                 GFP_KERNEL);
 370
 371         if (!balanced_kobject)
 372                 return -ENOMEM;
 373
 374         err = cpuquiet_kobject_init(balanced_kobject, &ktype_balanced,
 375                                 "balanced");
 376
 377         if (err)
 378                 kfree(balanced_kobject);
 379
 380         return err;
 381 }
 382
 383 static void balanced_stop(void)
 384 {
 385         /*
 386            first unregister the notifiers. This ensures the governor state
 387            can't be modified by a cpufreq transition
 388         */
 389         cpufreq_unregister_notifier(&balanced_cpufreq_nb,
 390                 CPUFREQ_TRANSITION_NOTIFIER);
 391
 392         /* now we can force the governor to be idle */
 393         balanced_state = IDLE;
 394         cancel_delayed_work_sync(&balanced_work);
 395         destroy_workqueue(balanced_wq);
 396         del_timer(&load_timer);
 397
 398         kobject_put(balanced_kobject);
 399 }
 400
 401 static int balanced_start(void)
 402 {
 403         int err, count;
 404         struct cpufreq_frequency_table *table;
 405         struct cpufreq_freqs initial_freq;
 406
 407         err = balanced_sysfs();
 408         if (err)
 409                 return err;
 410
 411         balanced_wq = alloc_workqueue("cpuquiet-balanced",
 412                         WQ_UNBOUND | WQ_RESCUER | WQ_FREEZABLE, 1);
 413         if (!balanced_wq)
 414                 return -ENOMEM;
 415
 416         INIT_DELAYED_WORK(&balanced_work, balanced_work_func);
 417
 418         up_delay = msecs_to_jiffies(100);
 419         down_delay = msecs_to_jiffies(2000);
 420
 421         table = cpufreq_frequency_get_table(0);
 422         for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++);
 423
 424         idle_top_freq = table[(count / 2) - 1].frequency;
 425         idle_bottom_freq = table[(count / 2) - 2].frequency;
 426
 427         cpufreq_register_notifier(&balanced_cpufreq_nb,
 428                 CPUFREQ_TRANSITION_NOTIFIER);
 429
 430         init_timer(&load_timer);
 431         load_timer.function = calculate_load_timer;
 432
 433         /*FIXME: Kick start the state machine by faking a freq notification*/
 434         initial_freq.new = cpufreq_get(0);
 435         if (initial_freq.new != 0)
 436                 balanced_cpufreq_transition(NULL, CPUFREQ_RESUMECHANGE,
 437                                                 &initial_freq);
 438         return 0;
 439 }
 440
 441 struct cpuquiet_governor balanced_governor = {
 442         .name           = "balanced",
 443         .start          = balanced_start,
 444         .stop           = balanced_stop,
 445         .owner          = THIS_MODULE,
 446 };
 447
 448 static int __init init_balanced(void)
 449 {
 450         return cpuquiet_register_governor(&balanced_governor);
 451 }
 452
 453 static void __exit exit_balanced(void)
 454 {
 455         cpuquiet_unregister_governor(&balanced_governor);
 456 }
 457
 458 MODULE_LICENSE("GPL");
 459 #ifdef CONFIG_CPUQUIET_DEFAULT_GOV_BALANCED
 460 fs_initcall(init_balanced);
 461 #else
 462 module_init(init_balanced);
 463 #endif
 464 module_exit(exit_balanced);
 465