2 * drivers/cpufreq/cpufreq_ondemand.c
4 * Copyright (C) 2001 Russell King
5 * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
6 * Jun Nakajima <jun.nakajima@intel.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 #include <linux/cpu.h>
16 #include <linux/percpu-defs.h>
17 #include <linux/slab.h>
18 #include <linux/tick.h>
20 #include "cpufreq_ondemand.h"
22 /* On-demand governor macros */
23 #define DEF_FREQUENCY_UP_THRESHOLD (80)
24 #define DEF_SAMPLING_DOWN_FACTOR (1)
25 #define MAX_SAMPLING_DOWN_FACTOR (100000)
26 #define MICRO_FREQUENCY_UP_THRESHOLD (95)
27 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
28 #define MIN_FREQUENCY_UP_THRESHOLD (11)
29 #define MAX_FREQUENCY_UP_THRESHOLD (100)
31 static struct od_ops od_ops
;
33 static unsigned int default_powersave_bias
;
36 * Not all CPUs want IO time to be accounted as busy; this depends on how
37 * efficient idling at a higher frequency/voltage is.
38 * Pavel Machek says this is not so for various generations of AMD and old
40 * Mike Chan (android.com) claims this is also not true for ARM.
41 * Because of this, whitelist specific known (series) of CPUs by default, and
42 * leave all others up to the user.
44 static int should_io_be_busy(void)
46 #if defined(CONFIG_X86)
48 * For Intel, Core 2 (model 15) and later have an efficient idle.
50 if (boot_cpu_data
.x86_vendor
== X86_VENDOR_INTEL
&&
51 boot_cpu_data
.x86
== 6 &&
52 boot_cpu_data
.x86_model
>= 15)
59 * Find right freq to be set now with powersave_bias on.
60 * Returns the freq_hi to be used right now and will set freq_hi_delay_us,
61 * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
63 static unsigned int generic_powersave_bias_target(struct cpufreq_policy
*policy
,
64 unsigned int freq_next
, unsigned int relation
)
66 unsigned int freq_req
, freq_reduc
, freq_avg
;
67 unsigned int freq_hi
, freq_lo
;
69 unsigned int delay_hi_us
;
70 struct policy_dbs_info
*policy_dbs
= policy
->governor_data
;
71 struct od_policy_dbs_info
*dbs_info
= to_dbs_info(policy_dbs
);
72 struct dbs_data
*dbs_data
= policy_dbs
->dbs_data
;
73 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
74 struct cpufreq_frequency_table
*freq_table
= policy
->freq_table
;
77 dbs_info
->freq_lo
= 0;
78 dbs_info
->freq_lo_delay_us
= 0;
82 index
= cpufreq_frequency_table_target(policy
, freq_next
, relation
);
83 freq_req
= freq_table
[index
].frequency
;
84 freq_reduc
= freq_req
* od_tuners
->powersave_bias
/ 1000;
85 freq_avg
= freq_req
- freq_reduc
;
87 /* Find freq bounds for freq_avg in freq_table */
88 index
= cpufreq_frequency_table_target(policy
, freq_avg
,
90 freq_lo
= freq_table
[index
].frequency
;
91 index
= cpufreq_frequency_table_target(policy
, freq_avg
,
93 freq_hi
= freq_table
[index
].frequency
;
95 /* Find out how long we have to be in hi and lo freqs */
96 if (freq_hi
== freq_lo
) {
97 dbs_info
->freq_lo
= 0;
98 dbs_info
->freq_lo_delay_us
= 0;
101 delay_hi_us
= (freq_avg
- freq_lo
) * dbs_data
->sampling_rate
;
102 delay_hi_us
+= (freq_hi
- freq_lo
) / 2;
103 delay_hi_us
/= freq_hi
- freq_lo
;
104 dbs_info
->freq_hi_delay_us
= delay_hi_us
;
105 dbs_info
->freq_lo
= freq_lo
;
106 dbs_info
->freq_lo_delay_us
= dbs_data
->sampling_rate
- delay_hi_us
;
110 static void ondemand_powersave_bias_init(struct cpufreq_policy
*policy
)
112 struct od_policy_dbs_info
*dbs_info
= to_dbs_info(policy
->governor_data
);
114 dbs_info
->freq_lo
= 0;
117 static void dbs_freq_increase(struct cpufreq_policy
*policy
, unsigned int freq
)
119 struct policy_dbs_info
*policy_dbs
= policy
->governor_data
;
120 struct dbs_data
*dbs_data
= policy_dbs
->dbs_data
;
121 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
123 if (od_tuners
->powersave_bias
)
124 freq
= od_ops
.powersave_bias_target(policy
, freq
,
126 else if (policy
->cur
== policy
->max
)
129 __cpufreq_driver_target(policy
, freq
, od_tuners
->powersave_bias
?
130 CPUFREQ_RELATION_L
: CPUFREQ_RELATION_H
);
134 * Every sampling_rate, we check, if current idle time is less than 20%
135 * (default), then we try to increase frequency. Else, we adjust the frequency
136 * proportional to load.
138 static void od_update(struct cpufreq_policy
*policy
)
140 struct policy_dbs_info
*policy_dbs
= policy
->governor_data
;
141 struct od_policy_dbs_info
*dbs_info
= to_dbs_info(policy_dbs
);
142 struct dbs_data
*dbs_data
= policy_dbs
->dbs_data
;
143 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
144 unsigned int load
= dbs_update(policy
);
146 dbs_info
->freq_lo
= 0;
148 /* Check for frequency increase */
149 if (load
> dbs_data
->up_threshold
) {
150 /* If switching to max speed, apply sampling_down_factor */
151 if (policy
->cur
< policy
->max
)
152 policy_dbs
->rate_mult
= dbs_data
->sampling_down_factor
;
153 dbs_freq_increase(policy
, policy
->max
);
155 /* Calculate the next frequency proportional to load */
156 unsigned int freq_next
, min_f
, max_f
;
158 min_f
= policy
->cpuinfo
.min_freq
;
159 max_f
= policy
->cpuinfo
.max_freq
;
160 freq_next
= min_f
+ load
* (max_f
- min_f
) / 100;
162 /* No longer fully busy, reset rate_mult */
163 policy_dbs
->rate_mult
= 1;
165 if (od_tuners
->powersave_bias
)
166 freq_next
= od_ops
.powersave_bias_target(policy
,
170 __cpufreq_driver_target(policy
, freq_next
, CPUFREQ_RELATION_C
);
174 static unsigned int od_dbs_timer(struct cpufreq_policy
*policy
)
176 struct policy_dbs_info
*policy_dbs
= policy
->governor_data
;
177 struct dbs_data
*dbs_data
= policy_dbs
->dbs_data
;
178 struct od_policy_dbs_info
*dbs_info
= to_dbs_info(policy_dbs
);
179 int sample_type
= dbs_info
->sample_type
;
181 /* Common NORMAL_SAMPLE setup */
182 dbs_info
->sample_type
= OD_NORMAL_SAMPLE
;
184 * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
187 if (sample_type
== OD_SUB_SAMPLE
&& policy_dbs
->sample_delay_ns
> 0) {
188 __cpufreq_driver_target(policy
, dbs_info
->freq_lo
,
190 return dbs_info
->freq_lo_delay_us
;
195 if (dbs_info
->freq_lo
) {
196 /* Setup timer for SUB_SAMPLE */
197 dbs_info
->sample_type
= OD_SUB_SAMPLE
;
198 return dbs_info
->freq_hi_delay_us
;
201 return dbs_data
->sampling_rate
* policy_dbs
->rate_mult
;
204 /************************** sysfs interface ************************/
205 static struct dbs_governor od_dbs_gov
;
207 static ssize_t
store_io_is_busy(struct gov_attr_set
*attr_set
, const char *buf
,
210 struct dbs_data
*dbs_data
= to_dbs_data(attr_set
);
214 ret
= sscanf(buf
, "%u", &input
);
217 dbs_data
->io_is_busy
= !!input
;
219 /* we need to re-evaluate prev_cpu_idle */
220 gov_update_cpu_data(dbs_data
);
225 static ssize_t
store_up_threshold(struct gov_attr_set
*attr_set
,
226 const char *buf
, size_t count
)
228 struct dbs_data
*dbs_data
= to_dbs_data(attr_set
);
231 ret
= sscanf(buf
, "%u", &input
);
233 if (ret
!= 1 || input
> MAX_FREQUENCY_UP_THRESHOLD
||
234 input
< MIN_FREQUENCY_UP_THRESHOLD
) {
238 dbs_data
->up_threshold
= input
;
242 static ssize_t
store_sampling_down_factor(struct gov_attr_set
*attr_set
,
243 const char *buf
, size_t count
)
245 struct dbs_data
*dbs_data
= to_dbs_data(attr_set
);
246 struct policy_dbs_info
*policy_dbs
;
249 ret
= sscanf(buf
, "%u", &input
);
251 if (ret
!= 1 || input
> MAX_SAMPLING_DOWN_FACTOR
|| input
< 1)
254 dbs_data
->sampling_down_factor
= input
;
256 /* Reset down sampling multiplier in case it was active */
257 list_for_each_entry(policy_dbs
, &attr_set
->policy_list
, list
) {
259 * Doing this without locking might lead to using different
260 * rate_mult values in od_update() and od_dbs_timer().
262 mutex_lock(&policy_dbs
->timer_mutex
);
263 policy_dbs
->rate_mult
= 1;
264 mutex_unlock(&policy_dbs
->timer_mutex
);
270 static ssize_t
store_ignore_nice_load(struct gov_attr_set
*attr_set
,
271 const char *buf
, size_t count
)
273 struct dbs_data
*dbs_data
= to_dbs_data(attr_set
);
277 ret
= sscanf(buf
, "%u", &input
);
284 if (input
== dbs_data
->ignore_nice_load
) { /* nothing to do */
287 dbs_data
->ignore_nice_load
= input
;
289 /* we need to re-evaluate prev_cpu_idle */
290 gov_update_cpu_data(dbs_data
);
295 static ssize_t
store_powersave_bias(struct gov_attr_set
*attr_set
,
296 const char *buf
, size_t count
)
298 struct dbs_data
*dbs_data
= to_dbs_data(attr_set
);
299 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
300 struct policy_dbs_info
*policy_dbs
;
303 ret
= sscanf(buf
, "%u", &input
);
311 od_tuners
->powersave_bias
= input
;
313 list_for_each_entry(policy_dbs
, &attr_set
->policy_list
, list
)
314 ondemand_powersave_bias_init(policy_dbs
->policy
);
319 gov_show_one_common(sampling_rate
);
320 gov_show_one_common(up_threshold
);
321 gov_show_one_common(sampling_down_factor
);
322 gov_show_one_common(ignore_nice_load
);
323 gov_show_one_common(min_sampling_rate
);
324 gov_show_one_common(io_is_busy
);
325 gov_show_one(od
, powersave_bias
);
327 gov_attr_rw(sampling_rate
);
328 gov_attr_rw(io_is_busy
);
329 gov_attr_rw(up_threshold
);
330 gov_attr_rw(sampling_down_factor
);
331 gov_attr_rw(ignore_nice_load
);
332 gov_attr_rw(powersave_bias
);
333 gov_attr_ro(min_sampling_rate
);
335 static struct attribute
*od_attributes
[] = {
336 &min_sampling_rate
.attr
,
339 &sampling_down_factor
.attr
,
340 &ignore_nice_load
.attr
,
341 &powersave_bias
.attr
,
346 /************************** sysfs end ************************/
348 static struct policy_dbs_info
*od_alloc(void)
350 struct od_policy_dbs_info
*dbs_info
;
352 dbs_info
= kzalloc(sizeof(*dbs_info
), GFP_KERNEL
);
353 return dbs_info
? &dbs_info
->policy_dbs
: NULL
;
356 static void od_free(struct policy_dbs_info
*policy_dbs
)
358 kfree(to_dbs_info(policy_dbs
));
361 static int od_init(struct dbs_data
*dbs_data
)
363 struct od_dbs_tuners
*tuners
;
367 tuners
= kzalloc(sizeof(*tuners
), GFP_KERNEL
);
372 idle_time
= get_cpu_idle_time_us(cpu
, NULL
);
374 if (idle_time
!= -1ULL) {
375 /* Idle micro accounting is supported. Use finer thresholds */
376 dbs_data
->up_threshold
= MICRO_FREQUENCY_UP_THRESHOLD
;
378 * In nohz/micro accounting case we set the minimum frequency
379 * not depending on HZ, but fixed (very low). The deferred
380 * timer might skip some samples if idle/sleeping as needed.
382 dbs_data
->min_sampling_rate
= MICRO_FREQUENCY_MIN_SAMPLE_RATE
;
384 dbs_data
->up_threshold
= DEF_FREQUENCY_UP_THRESHOLD
;
386 /* For correct statistics, we need 10 ticks for each measure */
387 dbs_data
->min_sampling_rate
= MIN_SAMPLING_RATE_RATIO
*
388 jiffies_to_usecs(10);
391 dbs_data
->sampling_down_factor
= DEF_SAMPLING_DOWN_FACTOR
;
392 dbs_data
->ignore_nice_load
= 0;
393 tuners
->powersave_bias
= default_powersave_bias
;
394 dbs_data
->io_is_busy
= should_io_be_busy();
396 dbs_data
->tuners
= tuners
;
400 static void od_exit(struct dbs_data
*dbs_data
)
402 kfree(dbs_data
->tuners
);
405 static void od_start(struct cpufreq_policy
*policy
)
407 struct od_policy_dbs_info
*dbs_info
= to_dbs_info(policy
->governor_data
);
409 dbs_info
->sample_type
= OD_NORMAL_SAMPLE
;
410 ondemand_powersave_bias_init(policy
);
413 static struct od_ops od_ops
= {
414 .powersave_bias_target
= generic_powersave_bias_target
,
417 static struct dbs_governor od_dbs_gov
= {
418 .gov
= CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
419 .kobj_type
= { .default_attrs
= od_attributes
},
420 .gov_dbs_timer
= od_dbs_timer
,
428 #define CPU_FREQ_GOV_ONDEMAND (&od_dbs_gov.gov)
430 static void od_set_powersave_bias(unsigned int powersave_bias
)
435 default_powersave_bias
= powersave_bias
;
436 cpumask_clear(&done
);
439 for_each_online_cpu(cpu
) {
440 struct cpufreq_policy
*policy
;
441 struct policy_dbs_info
*policy_dbs
;
442 struct dbs_data
*dbs_data
;
443 struct od_dbs_tuners
*od_tuners
;
445 if (cpumask_test_cpu(cpu
, &done
))
448 policy
= cpufreq_cpu_get_raw(cpu
);
449 if (!policy
|| policy
->governor
!= CPU_FREQ_GOV_ONDEMAND
)
452 policy_dbs
= policy
->governor_data
;
456 cpumask_or(&done
, &done
, policy
->cpus
);
458 dbs_data
= policy_dbs
->dbs_data
;
459 od_tuners
= dbs_data
->tuners
;
460 od_tuners
->powersave_bias
= default_powersave_bias
;
465 void od_register_powersave_bias_handler(unsigned int (*f
)
466 (struct cpufreq_policy
*, unsigned int, unsigned int),
467 unsigned int powersave_bias
)
469 od_ops
.powersave_bias_target
= f
;
470 od_set_powersave_bias(powersave_bias
);
472 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler
);
474 void od_unregister_powersave_bias_handler(void)
476 od_ops
.powersave_bias_target
= generic_powersave_bias_target
;
477 od_set_powersave_bias(0);
479 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler
);
481 static int __init
cpufreq_gov_dbs_init(void)
483 return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND
);
486 static void __exit
cpufreq_gov_dbs_exit(void)
488 cpufreq_unregister_governor(CPU_FREQ_GOV_ONDEMAND
);
491 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
492 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
493 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
494 "Low Latency Frequency Transition capable processors");
495 MODULE_LICENSE("GPL");
497 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
498 struct cpufreq_governor
*cpufreq_default_governor(void)
500 return CPU_FREQ_GOV_ONDEMAND
;
503 fs_initcall(cpufreq_gov_dbs_init
);
505 module_init(cpufreq_gov_dbs_init
);
507 module_exit(cpufreq_gov_dbs_exit
);