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/cpufreq.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/kernel_stat.h>
19 #include <linux/kobject.h>
20 #include <linux/module.h>
21 #include <linux/mutex.h>
22 #include <linux/percpu-defs.h>
23 #include <linux/sysfs.h>
24 #include <linux/tick.h>
25 #include <linux/types.h>
27 #include "cpufreq_governor.h"
29 /* On-demand governor macors */
30 #define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10)
31 #define DEF_FREQUENCY_UP_THRESHOLD (80)
32 #define DEF_SAMPLING_DOWN_FACTOR (1)
33 #define MAX_SAMPLING_DOWN_FACTOR (100000)
34 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3)
35 #define MICRO_FREQUENCY_UP_THRESHOLD (95)
36 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
37 #define MIN_FREQUENCY_UP_THRESHOLD (11)
38 #define MAX_FREQUENCY_UP_THRESHOLD (100)
40 static struct dbs_data od_dbs_data
;
41 static DEFINE_PER_CPU(struct od_cpu_dbs_info_s
, od_cpu_dbs_info
);
43 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
44 static struct cpufreq_governor cpufreq_gov_ondemand
;
47 static struct od_dbs_tuners od_tuners
= {
48 .up_threshold
= DEF_FREQUENCY_UP_THRESHOLD
,
49 .sampling_down_factor
= DEF_SAMPLING_DOWN_FACTOR
,
50 .down_differential
= DEF_FREQUENCY_DOWN_DIFFERENTIAL
,
55 static void ondemand_powersave_bias_init_cpu(int cpu
)
57 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
, cpu
);
59 dbs_info
->freq_table
= cpufreq_frequency_get_table(cpu
);
60 dbs_info
->freq_lo
= 0;
64 * Not all CPUs want IO time to be accounted as busy; this depends on how
65 * efficient idling at a higher frequency/voltage is.
66 * Pavel Machek says this is not so for various generations of AMD and old
68 * Mike Chan (androidlcom) calis this is also not true for ARM.
69 * Because of this, whitelist specific known (series) of CPUs by default, and
70 * leave all others up to the user.
72 static int should_io_be_busy(void)
74 #if defined(CONFIG_X86)
76 * For Intel, Core 2 (model 15) andl later have an efficient idle.
78 if (boot_cpu_data
.x86_vendor
== X86_VENDOR_INTEL
&&
79 boot_cpu_data
.x86
== 6 &&
80 boot_cpu_data
.x86_model
>= 15)
87 * Find right freq to be set now with powersave_bias on.
88 * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
89 * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
91 static unsigned int powersave_bias_target(struct cpufreq_policy
*policy
,
92 unsigned int freq_next
, unsigned int relation
)
94 unsigned int freq_req
, freq_reduc
, freq_avg
;
95 unsigned int freq_hi
, freq_lo
;
96 unsigned int index
= 0;
97 unsigned int jiffies_total
, jiffies_hi
, jiffies_lo
;
98 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
,
101 if (!dbs_info
->freq_table
) {
102 dbs_info
->freq_lo
= 0;
103 dbs_info
->freq_lo_jiffies
= 0;
107 cpufreq_frequency_table_target(policy
, dbs_info
->freq_table
, freq_next
,
109 freq_req
= dbs_info
->freq_table
[index
].frequency
;
110 freq_reduc
= freq_req
* od_tuners
.powersave_bias
/ 1000;
111 freq_avg
= freq_req
- freq_reduc
;
113 /* Find freq bounds for freq_avg in freq_table */
115 cpufreq_frequency_table_target(policy
, dbs_info
->freq_table
, freq_avg
,
116 CPUFREQ_RELATION_H
, &index
);
117 freq_lo
= dbs_info
->freq_table
[index
].frequency
;
119 cpufreq_frequency_table_target(policy
, dbs_info
->freq_table
, freq_avg
,
120 CPUFREQ_RELATION_L
, &index
);
121 freq_hi
= dbs_info
->freq_table
[index
].frequency
;
123 /* Find out how long we have to be in hi and lo freqs */
124 if (freq_hi
== freq_lo
) {
125 dbs_info
->freq_lo
= 0;
126 dbs_info
->freq_lo_jiffies
= 0;
129 jiffies_total
= usecs_to_jiffies(od_tuners
.sampling_rate
);
130 jiffies_hi
= (freq_avg
- freq_lo
) * jiffies_total
;
131 jiffies_hi
+= ((freq_hi
- freq_lo
) / 2);
132 jiffies_hi
/= (freq_hi
- freq_lo
);
133 jiffies_lo
= jiffies_total
- jiffies_hi
;
134 dbs_info
->freq_lo
= freq_lo
;
135 dbs_info
->freq_lo_jiffies
= jiffies_lo
;
136 dbs_info
->freq_hi_jiffies
= jiffies_hi
;
140 static void ondemand_powersave_bias_init(void)
143 for_each_online_cpu(i
) {
144 ondemand_powersave_bias_init_cpu(i
);
148 static void dbs_freq_increase(struct cpufreq_policy
*p
, unsigned int freq
)
150 if (od_tuners
.powersave_bias
)
151 freq
= powersave_bias_target(p
, freq
, CPUFREQ_RELATION_H
);
152 else if (p
->cur
== p
->max
)
155 __cpufreq_driver_target(p
, freq
, od_tuners
.powersave_bias
?
156 CPUFREQ_RELATION_L
: CPUFREQ_RELATION_H
);
160 * Every sampling_rate, we check, if current idle time is less than 20%
161 * (default), then we try to increase frequency Every sampling_rate, we look for
162 * a the lowest frequency which can sustain the load while keeping idle time
163 * over 30%. If such a frequency exist, we try to decrease to this frequency.
165 * Any frequency increase takes it to the maximum frequency. Frequency reduction
166 * happens at minimum steps of 5% (default) of current frequency
168 static void od_check_cpu(int cpu
, unsigned int load_freq
)
170 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
, cpu
);
171 struct cpufreq_policy
*policy
= dbs_info
->cdbs
.cur_policy
;
173 dbs_info
->freq_lo
= 0;
175 /* Check for frequency increase */
176 if (load_freq
> od_tuners
.up_threshold
* policy
->cur
) {
177 /* If switching to max speed, apply sampling_down_factor */
178 if (policy
->cur
< policy
->max
)
179 dbs_info
->rate_mult
=
180 od_tuners
.sampling_down_factor
;
181 dbs_freq_increase(policy
, policy
->max
);
185 /* Check for frequency decrease */
186 /* if we cannot reduce the frequency anymore, break out early */
187 if (policy
->cur
== policy
->min
)
191 * The optimal frequency is the frequency that is the lowest that can
192 * support the current CPU usage without triggering the up policy. To be
193 * safe, we focus 10 points under the threshold.
195 if (load_freq
< (od_tuners
.up_threshold
- od_tuners
.down_differential
) *
197 unsigned int freq_next
;
198 freq_next
= load_freq
/ (od_tuners
.up_threshold
-
199 od_tuners
.down_differential
);
201 /* No longer fully busy, reset rate_mult */
202 dbs_info
->rate_mult
= 1;
204 if (freq_next
< policy
->min
)
205 freq_next
= policy
->min
;
207 if (!od_tuners
.powersave_bias
) {
208 __cpufreq_driver_target(policy
, freq_next
,
211 int freq
= powersave_bias_target(policy
, freq_next
,
213 __cpufreq_driver_target(policy
, freq
,
219 static void od_dbs_timer(struct work_struct
*work
)
221 struct od_cpu_dbs_info_s
*dbs_info
=
222 container_of(work
, struct od_cpu_dbs_info_s
, cdbs
.work
.work
);
223 unsigned int cpu
= dbs_info
->cdbs
.cpu
;
224 int delay
, sample_type
= dbs_info
->sample_type
;
226 mutex_lock(&dbs_info
->cdbs
.timer_mutex
);
228 /* Common NORMAL_SAMPLE setup */
229 dbs_info
->sample_type
= OD_NORMAL_SAMPLE
;
230 if (sample_type
== OD_SUB_SAMPLE
) {
231 delay
= dbs_info
->freq_lo_jiffies
;
232 __cpufreq_driver_target(dbs_info
->cdbs
.cur_policy
,
233 dbs_info
->freq_lo
, CPUFREQ_RELATION_H
);
235 dbs_check_cpu(&od_dbs_data
, cpu
);
236 if (dbs_info
->freq_lo
) {
237 /* Setup timer for SUB_SAMPLE */
238 dbs_info
->sample_type
= OD_SUB_SAMPLE
;
239 delay
= dbs_info
->freq_hi_jiffies
;
241 delay
= delay_for_sampling_rate(od_tuners
.sampling_rate
242 * dbs_info
->rate_mult
);
246 schedule_delayed_work_on(cpu
, &dbs_info
->cdbs
.work
, delay
);
247 mutex_unlock(&dbs_info
->cdbs
.timer_mutex
);
250 /************************** sysfs interface ************************/
252 static ssize_t
show_sampling_rate_min(struct kobject
*kobj
,
253 struct attribute
*attr
, char *buf
)
255 return sprintf(buf
, "%u\n", od_dbs_data
.min_sampling_rate
);
259 * update_sampling_rate - update sampling rate effective immediately if needed.
260 * @new_rate: new sampling rate
262 * If new rate is smaller than the old, simply updaing
263 * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
264 * original sampling_rate was 1 second and the requested new sampling rate is 10
265 * ms because the user needs immediate reaction from ondemand governor, but not
266 * sure if higher frequency will be required or not, then, the governor may
267 * change the sampling rate too late; up to 1 second later. Thus, if we are
268 * reducing the sampling rate, we need to make the new value effective
271 static void update_sampling_rate(unsigned int new_rate
)
275 od_tuners
.sampling_rate
= new_rate
= max(new_rate
,
276 od_dbs_data
.min_sampling_rate
);
278 for_each_online_cpu(cpu
) {
279 struct cpufreq_policy
*policy
;
280 struct od_cpu_dbs_info_s
*dbs_info
;
281 unsigned long next_sampling
, appointed_at
;
283 policy
= cpufreq_cpu_get(cpu
);
286 if (policy
->governor
!= &cpufreq_gov_ondemand
) {
287 cpufreq_cpu_put(policy
);
290 dbs_info
= &per_cpu(od_cpu_dbs_info
, policy
->cpu
);
291 cpufreq_cpu_put(policy
);
293 mutex_lock(&dbs_info
->cdbs
.timer_mutex
);
295 if (!delayed_work_pending(&dbs_info
->cdbs
.work
)) {
296 mutex_unlock(&dbs_info
->cdbs
.timer_mutex
);
300 next_sampling
= jiffies
+ usecs_to_jiffies(new_rate
);
301 appointed_at
= dbs_info
->cdbs
.work
.timer
.expires
;
303 if (time_before(next_sampling
, appointed_at
)) {
305 mutex_unlock(&dbs_info
->cdbs
.timer_mutex
);
306 cancel_delayed_work_sync(&dbs_info
->cdbs
.work
);
307 mutex_lock(&dbs_info
->cdbs
.timer_mutex
);
309 schedule_delayed_work_on(dbs_info
->cdbs
.cpu
,
310 &dbs_info
->cdbs
.work
,
311 usecs_to_jiffies(new_rate
));
314 mutex_unlock(&dbs_info
->cdbs
.timer_mutex
);
318 static ssize_t
store_sampling_rate(struct kobject
*a
, struct attribute
*b
,
319 const char *buf
, size_t count
)
323 ret
= sscanf(buf
, "%u", &input
);
326 update_sampling_rate(input
);
330 static ssize_t
store_io_is_busy(struct kobject
*a
, struct attribute
*b
,
331 const char *buf
, size_t count
)
336 ret
= sscanf(buf
, "%u", &input
);
339 od_tuners
.io_is_busy
= !!input
;
343 static ssize_t
store_up_threshold(struct kobject
*a
, struct attribute
*b
,
344 const char *buf
, size_t count
)
348 ret
= sscanf(buf
, "%u", &input
);
350 if (ret
!= 1 || input
> MAX_FREQUENCY_UP_THRESHOLD
||
351 input
< MIN_FREQUENCY_UP_THRESHOLD
) {
354 od_tuners
.up_threshold
= input
;
358 static ssize_t
store_sampling_down_factor(struct kobject
*a
,
359 struct attribute
*b
, const char *buf
, size_t count
)
361 unsigned int input
, j
;
363 ret
= sscanf(buf
, "%u", &input
);
365 if (ret
!= 1 || input
> MAX_SAMPLING_DOWN_FACTOR
|| input
< 1)
367 od_tuners
.sampling_down_factor
= input
;
369 /* Reset down sampling multiplier in case it was active */
370 for_each_online_cpu(j
) {
371 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
,
373 dbs_info
->rate_mult
= 1;
378 static ssize_t
store_ignore_nice_load(struct kobject
*a
, struct attribute
*b
,
379 const char *buf
, size_t count
)
386 ret
= sscanf(buf
, "%u", &input
);
393 if (input
== od_tuners
.ignore_nice
) { /* nothing to do */
396 od_tuners
.ignore_nice
= input
;
398 /* we need to re-evaluate prev_cpu_idle */
399 for_each_online_cpu(j
) {
400 struct od_cpu_dbs_info_s
*dbs_info
;
401 dbs_info
= &per_cpu(od_cpu_dbs_info
, j
);
402 dbs_info
->cdbs
.prev_cpu_idle
= get_cpu_idle_time(j
,
403 &dbs_info
->cdbs
.prev_cpu_wall
);
404 if (od_tuners
.ignore_nice
)
405 dbs_info
->cdbs
.prev_cpu_nice
=
406 kcpustat_cpu(j
).cpustat
[CPUTIME_NICE
];
412 static ssize_t
store_powersave_bias(struct kobject
*a
, struct attribute
*b
,
413 const char *buf
, size_t count
)
417 ret
= sscanf(buf
, "%u", &input
);
425 od_tuners
.powersave_bias
= input
;
426 ondemand_powersave_bias_init();
430 show_one(od
, sampling_rate
, sampling_rate
);
431 show_one(od
, io_is_busy
, io_is_busy
);
432 show_one(od
, up_threshold
, up_threshold
);
433 show_one(od
, sampling_down_factor
, sampling_down_factor
);
434 show_one(od
, ignore_nice_load
, ignore_nice
);
435 show_one(od
, powersave_bias
, powersave_bias
);
437 define_one_global_rw(sampling_rate
);
438 define_one_global_rw(io_is_busy
);
439 define_one_global_rw(up_threshold
);
440 define_one_global_rw(sampling_down_factor
);
441 define_one_global_rw(ignore_nice_load
);
442 define_one_global_rw(powersave_bias
);
443 define_one_global_ro(sampling_rate_min
);
445 static struct attribute
*dbs_attributes
[] = {
446 &sampling_rate_min
.attr
,
449 &sampling_down_factor
.attr
,
450 &ignore_nice_load
.attr
,
451 &powersave_bias
.attr
,
456 static struct attribute_group od_attr_group
= {
457 .attrs
= dbs_attributes
,
461 /************************** sysfs end ************************/
463 define_get_cpu_dbs_routines(od_cpu_dbs_info
);
465 static struct od_ops od_ops
= {
466 .io_busy
= should_io_be_busy
,
467 .powersave_bias_init_cpu
= ondemand_powersave_bias_init_cpu
,
468 .powersave_bias_target
= powersave_bias_target
,
469 .freq_increase
= dbs_freq_increase
,
472 static struct dbs_data od_dbs_data
= {
473 .governor
= GOV_ONDEMAND
,
474 .attr_group
= &od_attr_group
,
475 .tuners
= &od_tuners
,
476 .get_cpu_cdbs
= get_cpu_cdbs
,
477 .get_cpu_dbs_info_s
= get_cpu_dbs_info_s
,
478 .gov_dbs_timer
= od_dbs_timer
,
479 .gov_check_cpu
= od_check_cpu
,
483 static int od_cpufreq_governor_dbs(struct cpufreq_policy
*policy
,
486 return cpufreq_governor_dbs(&od_dbs_data
, policy
, event
);
489 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
492 struct cpufreq_governor cpufreq_gov_ondemand
= {
494 .governor
= od_cpufreq_governor_dbs
,
495 .max_transition_latency
= TRANSITION_LATENCY_LIMIT
,
496 .owner
= THIS_MODULE
,
499 static int __init
cpufreq_gov_dbs_init(void)
504 mutex_init(&od_dbs_data
.mutex
);
505 idle_time
= get_cpu_idle_time_us(cpu
, NULL
);
507 if (idle_time
!= -1ULL) {
508 /* Idle micro accounting is supported. Use finer thresholds */
509 od_tuners
.up_threshold
= MICRO_FREQUENCY_UP_THRESHOLD
;
510 od_tuners
.down_differential
= MICRO_FREQUENCY_DOWN_DIFFERENTIAL
;
512 * In nohz/micro accounting case we set the minimum frequency
513 * not depending on HZ, but fixed (very low). The deferred
514 * timer might skip some samples if idle/sleeping as needed.
516 od_dbs_data
.min_sampling_rate
= MICRO_FREQUENCY_MIN_SAMPLE_RATE
;
518 /* For correct statistics, we need 10 ticks for each measure */
519 od_dbs_data
.min_sampling_rate
= MIN_SAMPLING_RATE_RATIO
*
520 jiffies_to_usecs(10);
523 return cpufreq_register_governor(&cpufreq_gov_ondemand
);
526 static void __exit
cpufreq_gov_dbs_exit(void)
528 cpufreq_unregister_governor(&cpufreq_gov_ondemand
);
531 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
532 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
533 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
534 "Low Latency Frequency Transition capable processors");
535 MODULE_LICENSE("GPL");
537 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
538 fs_initcall(cpufreq_gov_dbs_init
);
540 module_init(cpufreq_gov_dbs_init
);
542 module_exit(cpufreq_gov_dbs_exit
);