1 // SPDX-License-Identifier: GPL-2.0-only
3 * drivers/cpufreq/cpufreq_ondemand.c
5 * Copyright (C) 2001 Russell King
6 * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
7 * Jun Nakajima <jun.nakajima@intel.com>
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 #include <linux/cpu.h>
13 #include <linux/percpu-defs.h>
14 #include <linux/slab.h>
15 #include <linux/tick.h>
16 #include <linux/sched/cpufreq.h>
18 #include "cpufreq_ondemand.h"
20 /* On-demand governor macros */
21 #define DEF_FREQUENCY_UP_THRESHOLD (80)
22 #define DEF_SAMPLING_DOWN_FACTOR (1)
23 #define MAX_SAMPLING_DOWN_FACTOR (100000)
24 #define MICRO_FREQUENCY_UP_THRESHOLD (95)
25 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
26 #define MIN_FREQUENCY_UP_THRESHOLD (1)
27 #define MAX_FREQUENCY_UP_THRESHOLD (100)
29 static struct od_ops od_ops;
31 static unsigned int default_powersave_bias;
34 * Not all CPUs want IO time to be accounted as busy; this depends on how
35 * efficient idling at a higher frequency/voltage is.
36 * Pavel Machek says this is not so for various generations of AMD and old
38 * Mike Chan (android.com) claims this is also not true for ARM.
39 * Because of this, whitelist specific known (series) of CPUs by default, and
40 * leave all others up to the user.
42 static int should_io_be_busy(void)
44 #if defined(CONFIG_X86)
46 * For Intel, Core 2 (model 15) and later have an efficient idle.
48 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
49 boot_cpu_data.x86 == 6 &&
50 boot_cpu_data.x86_model >= 15)
57 * Find right freq to be set now with powersave_bias on.
58 * Returns the freq_hi to be used right now and will set freq_hi_delay_us,
59 * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
61 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
62 unsigned int freq_next, unsigned int relation)
64 unsigned int freq_req, freq_reduc, freq_avg;
65 unsigned int freq_hi, freq_lo;
67 unsigned int delay_hi_us;
68 struct policy_dbs_info *policy_dbs = policy->governor_data;
69 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
70 struct dbs_data *dbs_data = policy_dbs->dbs_data;
71 struct od_dbs_tuners *od_tuners = dbs_data->tuners;
72 struct cpufreq_frequency_table *freq_table = policy->freq_table;
75 dbs_info->freq_lo = 0;
76 dbs_info->freq_lo_delay_us = 0;
80 index = cpufreq_frequency_table_target(policy, freq_next, relation);
81 freq_req = freq_table[index].frequency;
82 freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
83 freq_avg = freq_req - freq_reduc;
85 /* Find freq bounds for freq_avg in freq_table */
86 index = cpufreq_table_find_index_h(policy, freq_avg);
87 freq_lo = freq_table[index].frequency;
88 index = cpufreq_table_find_index_l(policy, freq_avg);
89 freq_hi = freq_table[index].frequency;
91 /* Find out how long we have to be in hi and lo freqs */
92 if (freq_hi == freq_lo) {
93 dbs_info->freq_lo = 0;
94 dbs_info->freq_lo_delay_us = 0;
97 delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
98 delay_hi_us += (freq_hi - freq_lo) / 2;
99 delay_hi_us /= freq_hi - freq_lo;
100 dbs_info->freq_hi_delay_us = delay_hi_us;
101 dbs_info->freq_lo = freq_lo;
102 dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
106 static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
108 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
110 dbs_info->freq_lo = 0;
113 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
115 struct policy_dbs_info *policy_dbs = policy->governor_data;
116 struct dbs_data *dbs_data = policy_dbs->dbs_data;
117 struct od_dbs_tuners *od_tuners = dbs_data->tuners;
119 if (od_tuners->powersave_bias)
120 freq = od_ops.powersave_bias_target(policy, freq,
122 else if (policy->cur == policy->max)
125 __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
126 CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
130 * Every sampling_rate, we check, if current idle time is less than 20%
131 * (default), then we try to increase frequency. Else, we adjust the frequency
132 * proportional to load.
134 static void od_update(struct cpufreq_policy *policy)
136 struct policy_dbs_info *policy_dbs = policy->governor_data;
137 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
138 struct dbs_data *dbs_data = policy_dbs->dbs_data;
139 struct od_dbs_tuners *od_tuners = dbs_data->tuners;
140 unsigned int load = dbs_update(policy);
142 dbs_info->freq_lo = 0;
144 /* Check for frequency increase */
145 if (load > dbs_data->up_threshold) {
146 /* If switching to max speed, apply sampling_down_factor */
147 if (policy->cur < policy->max)
148 policy_dbs->rate_mult = dbs_data->sampling_down_factor;
149 dbs_freq_increase(policy, policy->max);
151 /* Calculate the next frequency proportional to load */
152 unsigned int freq_next, min_f, max_f;
154 min_f = policy->cpuinfo.min_freq;
155 max_f = policy->cpuinfo.max_freq;
156 freq_next = min_f + load * (max_f - min_f) / 100;
158 /* No longer fully busy, reset rate_mult */
159 policy_dbs->rate_mult = 1;
161 if (od_tuners->powersave_bias)
162 freq_next = od_ops.powersave_bias_target(policy,
166 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
170 static unsigned int od_dbs_update(struct cpufreq_policy *policy)
172 struct policy_dbs_info *policy_dbs = policy->governor_data;
173 struct dbs_data *dbs_data = policy_dbs->dbs_data;
174 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
175 int sample_type = dbs_info->sample_type;
177 /* Common NORMAL_SAMPLE setup */
178 dbs_info->sample_type = OD_NORMAL_SAMPLE;
180 * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
183 if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
184 __cpufreq_driver_target(policy, dbs_info->freq_lo,
186 return dbs_info->freq_lo_delay_us;
191 if (dbs_info->freq_lo) {
192 /* Setup SUB_SAMPLE */
193 dbs_info->sample_type = OD_SUB_SAMPLE;
194 return dbs_info->freq_hi_delay_us;
197 return dbs_data->sampling_rate * policy_dbs->rate_mult;
200 /************************** sysfs interface ************************/
201 static struct dbs_governor od_dbs_gov;
203 static ssize_t store_io_is_busy(struct gov_attr_set *attr_set, const char *buf,
206 struct dbs_data *dbs_data = to_dbs_data(attr_set);
210 ret = sscanf(buf, "%u", &input);
213 dbs_data->io_is_busy = !!input;
215 /* we need to re-evaluate prev_cpu_idle */
216 gov_update_cpu_data(dbs_data);
221 static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
222 const char *buf, size_t count)
224 struct dbs_data *dbs_data = to_dbs_data(attr_set);
227 ret = sscanf(buf, "%u", &input);
229 if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
230 input < MIN_FREQUENCY_UP_THRESHOLD) {
234 dbs_data->up_threshold = input;
238 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
239 const char *buf, size_t count)
241 struct dbs_data *dbs_data = to_dbs_data(attr_set);
242 struct policy_dbs_info *policy_dbs;
245 ret = sscanf(buf, "%u", &input);
247 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
250 dbs_data->sampling_down_factor = input;
252 /* Reset down sampling multiplier in case it was active */
253 list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
255 * Doing this without locking might lead to using different
256 * rate_mult values in od_update() and od_dbs_update().
258 mutex_lock(&policy_dbs->update_mutex);
259 policy_dbs->rate_mult = 1;
260 mutex_unlock(&policy_dbs->update_mutex);
266 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
267 const char *buf, size_t count)
269 struct dbs_data *dbs_data = to_dbs_data(attr_set);
273 ret = sscanf(buf, "%u", &input);
280 if (input == dbs_data->ignore_nice_load) { /* nothing to do */
283 dbs_data->ignore_nice_load = input;
285 /* we need to re-evaluate prev_cpu_idle */
286 gov_update_cpu_data(dbs_data);
291 static ssize_t store_powersave_bias(struct gov_attr_set *attr_set,
292 const char *buf, size_t count)
294 struct dbs_data *dbs_data = to_dbs_data(attr_set);
295 struct od_dbs_tuners *od_tuners = dbs_data->tuners;
296 struct policy_dbs_info *policy_dbs;
299 ret = sscanf(buf, "%u", &input);
307 od_tuners->powersave_bias = input;
309 list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
310 ondemand_powersave_bias_init(policy_dbs->policy);
315 gov_show_one_common(sampling_rate);
316 gov_show_one_common(up_threshold);
317 gov_show_one_common(sampling_down_factor);
318 gov_show_one_common(ignore_nice_load);
319 gov_show_one_common(io_is_busy);
320 gov_show_one(od, powersave_bias);
322 gov_attr_rw(sampling_rate);
323 gov_attr_rw(io_is_busy);
324 gov_attr_rw(up_threshold);
325 gov_attr_rw(sampling_down_factor);
326 gov_attr_rw(ignore_nice_load);
327 gov_attr_rw(powersave_bias);
329 static struct attribute *od_attributes[] = {
332 &sampling_down_factor.attr,
333 &ignore_nice_load.attr,
334 &powersave_bias.attr,
339 /************************** sysfs end ************************/
341 static struct policy_dbs_info *od_alloc(void)
343 struct od_policy_dbs_info *dbs_info;
345 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
346 return dbs_info ? &dbs_info->policy_dbs : NULL;
349 static void od_free(struct policy_dbs_info *policy_dbs)
351 kfree(to_dbs_info(policy_dbs));
354 static int od_init(struct dbs_data *dbs_data)
356 struct od_dbs_tuners *tuners;
360 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
365 idle_time = get_cpu_idle_time_us(cpu, NULL);
367 if (idle_time != -1ULL) {
368 /* Idle micro accounting is supported. Use finer thresholds */
369 dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
371 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
374 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
375 dbs_data->ignore_nice_load = 0;
376 tuners->powersave_bias = default_powersave_bias;
377 dbs_data->io_is_busy = should_io_be_busy();
379 dbs_data->tuners = tuners;
383 static void od_exit(struct dbs_data *dbs_data)
385 kfree(dbs_data->tuners);
388 static void od_start(struct cpufreq_policy *policy)
390 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
392 dbs_info->sample_type = OD_NORMAL_SAMPLE;
393 ondemand_powersave_bias_init(policy);
396 static struct od_ops od_ops = {
397 .powersave_bias_target = generic_powersave_bias_target,
400 static struct dbs_governor od_dbs_gov = {
401 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
402 .kobj_type = { .default_attrs = od_attributes },
403 .gov_dbs_update = od_dbs_update,
411 #define CPU_FREQ_GOV_ONDEMAND (od_dbs_gov.gov)
413 static void od_set_powersave_bias(unsigned int powersave_bias)
418 default_powersave_bias = powersave_bias;
419 cpumask_clear(&done);
422 for_each_online_cpu(cpu) {
423 struct cpufreq_policy *policy;
424 struct policy_dbs_info *policy_dbs;
425 struct dbs_data *dbs_data;
426 struct od_dbs_tuners *od_tuners;
428 if (cpumask_test_cpu(cpu, &done))
431 policy = cpufreq_cpu_get_raw(cpu);
432 if (!policy || policy->governor != &CPU_FREQ_GOV_ONDEMAND)
435 policy_dbs = policy->governor_data;
439 cpumask_or(&done, &done, policy->cpus);
441 dbs_data = policy_dbs->dbs_data;
442 od_tuners = dbs_data->tuners;
443 od_tuners->powersave_bias = default_powersave_bias;
448 void od_register_powersave_bias_handler(unsigned int (*f)
449 (struct cpufreq_policy *, unsigned int, unsigned int),
450 unsigned int powersave_bias)
452 od_ops.powersave_bias_target = f;
453 od_set_powersave_bias(powersave_bias);
455 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
457 void od_unregister_powersave_bias_handler(void)
459 od_ops.powersave_bias_target = generic_powersave_bias_target;
460 od_set_powersave_bias(0);
462 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
464 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
465 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
466 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
467 "Low Latency Frequency Transition capable processors");
468 MODULE_LICENSE("GPL");
470 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
471 struct cpufreq_governor *cpufreq_default_governor(void)
473 return &CPU_FREQ_GOV_ONDEMAND;
477 cpufreq_governor_init(CPU_FREQ_GOV_ONDEMAND);
478 cpufreq_governor_exit(CPU_FREQ_GOV_ONDEMAND);