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>
19 #include "cpufreq_governor.h"
21 /* On-demand governor macros */
22 #define DEF_FREQUENCY_UP_THRESHOLD (80)
23 #define DEF_SAMPLING_DOWN_FACTOR (1)
24 #define MAX_SAMPLING_DOWN_FACTOR (100000)
25 #define MICRO_FREQUENCY_UP_THRESHOLD (95)
26 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
27 #define MIN_FREQUENCY_UP_THRESHOLD (11)
28 #define MAX_FREQUENCY_UP_THRESHOLD (100)
30 static DEFINE_PER_CPU(struct od_cpu_dbs_info_s
, od_cpu_dbs_info
);
32 static struct od_ops od_ops
;
34 static unsigned int default_powersave_bias
;
36 static void ondemand_powersave_bias_init_cpu(int cpu
)
38 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
, cpu
);
40 dbs_info
->freq_table
= cpufreq_frequency_get_table(cpu
);
41 dbs_info
->freq_lo
= 0;
45 * Not all CPUs want IO time to be accounted as busy; this depends on how
46 * efficient idling at a higher frequency/voltage is.
47 * Pavel Machek says this is not so for various generations of AMD and old
49 * Mike Chan (android.com) claims this is also not true for ARM.
50 * Because of this, whitelist specific known (series) of CPUs by default, and
51 * leave all others up to the user.
53 static int should_io_be_busy(void)
55 #if defined(CONFIG_X86)
57 * For Intel, Core 2 (model 15) and later have an efficient idle.
59 if (boot_cpu_data
.x86_vendor
== X86_VENDOR_INTEL
&&
60 boot_cpu_data
.x86
== 6 &&
61 boot_cpu_data
.x86_model
>= 15)
68 * Find right freq to be set now with powersave_bias on.
69 * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
70 * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
72 static unsigned int generic_powersave_bias_target(struct cpufreq_policy
*policy
,
73 unsigned int freq_next
, unsigned int relation
)
75 unsigned int freq_req
, freq_reduc
, freq_avg
;
76 unsigned int freq_hi
, freq_lo
;
77 unsigned int index
= 0;
78 unsigned int jiffies_total
, jiffies_hi
, jiffies_lo
;
79 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
,
81 struct policy_dbs_info
*policy_dbs
= policy
->governor_data
;
82 struct dbs_data
*dbs_data
= policy_dbs
->dbs_data
;
83 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
85 if (!dbs_info
->freq_table
) {
86 dbs_info
->freq_lo
= 0;
87 dbs_info
->freq_lo_jiffies
= 0;
91 cpufreq_frequency_table_target(policy
, dbs_info
->freq_table
, freq_next
,
93 freq_req
= dbs_info
->freq_table
[index
].frequency
;
94 freq_reduc
= freq_req
* od_tuners
->powersave_bias
/ 1000;
95 freq_avg
= freq_req
- freq_reduc
;
97 /* Find freq bounds for freq_avg in freq_table */
99 cpufreq_frequency_table_target(policy
, dbs_info
->freq_table
, freq_avg
,
100 CPUFREQ_RELATION_H
, &index
);
101 freq_lo
= dbs_info
->freq_table
[index
].frequency
;
103 cpufreq_frequency_table_target(policy
, dbs_info
->freq_table
, freq_avg
,
104 CPUFREQ_RELATION_L
, &index
);
105 freq_hi
= dbs_info
->freq_table
[index
].frequency
;
107 /* Find out how long we have to be in hi and lo freqs */
108 if (freq_hi
== freq_lo
) {
109 dbs_info
->freq_lo
= 0;
110 dbs_info
->freq_lo_jiffies
= 0;
113 jiffies_total
= usecs_to_jiffies(dbs_data
->sampling_rate
);
114 jiffies_hi
= (freq_avg
- freq_lo
) * jiffies_total
;
115 jiffies_hi
+= ((freq_hi
- freq_lo
) / 2);
116 jiffies_hi
/= (freq_hi
- freq_lo
);
117 jiffies_lo
= jiffies_total
- jiffies_hi
;
118 dbs_info
->freq_lo
= freq_lo
;
119 dbs_info
->freq_lo_jiffies
= jiffies_lo
;
120 dbs_info
->freq_hi_jiffies
= jiffies_hi
;
124 static void ondemand_powersave_bias_init(void)
127 for_each_online_cpu(i
) {
128 ondemand_powersave_bias_init_cpu(i
);
132 static void dbs_freq_increase(struct cpufreq_policy
*policy
, unsigned int freq
)
134 struct policy_dbs_info
*policy_dbs
= policy
->governor_data
;
135 struct dbs_data
*dbs_data
= policy_dbs
->dbs_data
;
136 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
138 if (od_tuners
->powersave_bias
)
139 freq
= od_ops
.powersave_bias_target(policy
, freq
,
141 else if (policy
->cur
== policy
->max
)
144 __cpufreq_driver_target(policy
, freq
, od_tuners
->powersave_bias
?
145 CPUFREQ_RELATION_L
: CPUFREQ_RELATION_H
);
149 * Every sampling_rate, we check, if current idle time is less than 20%
150 * (default), then we try to increase frequency. Else, we adjust the frequency
151 * proportional to load.
153 static void od_check_cpu(int cpu
, unsigned int load
)
155 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
, cpu
);
156 struct policy_dbs_info
*policy_dbs
= dbs_info
->cdbs
.policy_dbs
;
157 struct cpufreq_policy
*policy
= policy_dbs
->policy
;
158 struct dbs_data
*dbs_data
= policy_dbs
->dbs_data
;
159 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
161 dbs_info
->freq_lo
= 0;
163 /* Check for frequency increase */
164 if (load
> dbs_data
->up_threshold
) {
165 /* If switching to max speed, apply sampling_down_factor */
166 if (policy
->cur
< policy
->max
)
167 dbs_info
->rate_mult
= dbs_data
->sampling_down_factor
;
168 dbs_freq_increase(policy
, policy
->max
);
170 /* Calculate the next frequency proportional to load */
171 unsigned int freq_next
, min_f
, max_f
;
173 min_f
= policy
->cpuinfo
.min_freq
;
174 max_f
= policy
->cpuinfo
.max_freq
;
175 freq_next
= min_f
+ load
* (max_f
- min_f
) / 100;
177 /* No longer fully busy, reset rate_mult */
178 dbs_info
->rate_mult
= 1;
180 if (!od_tuners
->powersave_bias
) {
181 __cpufreq_driver_target(policy
, freq_next
,
186 freq_next
= od_ops
.powersave_bias_target(policy
, freq_next
,
188 __cpufreq_driver_target(policy
, freq_next
, CPUFREQ_RELATION_C
);
192 static unsigned int od_dbs_timer(struct cpufreq_policy
*policy
)
194 struct policy_dbs_info
*policy_dbs
= policy
->governor_data
;
195 struct dbs_data
*dbs_data
= policy_dbs
->dbs_data
;
196 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
, policy
->cpu
);
197 int delay
= 0, sample_type
= dbs_info
->sample_type
;
199 /* Common NORMAL_SAMPLE setup */
200 dbs_info
->sample_type
= OD_NORMAL_SAMPLE
;
201 if (sample_type
== OD_SUB_SAMPLE
) {
202 delay
= dbs_info
->freq_lo_jiffies
;
203 __cpufreq_driver_target(policy
, dbs_info
->freq_lo
,
206 dbs_check_cpu(policy
);
207 if (dbs_info
->freq_lo
) {
208 /* Setup timer for SUB_SAMPLE */
209 dbs_info
->sample_type
= OD_SUB_SAMPLE
;
210 delay
= dbs_info
->freq_hi_jiffies
;
215 delay
= delay_for_sampling_rate(dbs_data
->sampling_rate
216 * dbs_info
->rate_mult
);
221 /************************** sysfs interface ************************/
222 static struct dbs_governor od_dbs_gov
;
224 static ssize_t
store_io_is_busy(struct dbs_data
*dbs_data
, const char *buf
,
227 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
232 ret
= sscanf(buf
, "%u", &input
);
235 od_tuners
->io_is_busy
= !!input
;
237 /* we need to re-evaluate prev_cpu_idle */
238 for_each_online_cpu(j
) {
239 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
,
241 dbs_info
->cdbs
.prev_cpu_idle
= get_cpu_idle_time(j
,
242 &dbs_info
->cdbs
.prev_cpu_wall
, od_tuners
->io_is_busy
);
247 static ssize_t
store_up_threshold(struct dbs_data
*dbs_data
, const char *buf
,
252 ret
= sscanf(buf
, "%u", &input
);
254 if (ret
!= 1 || input
> MAX_FREQUENCY_UP_THRESHOLD
||
255 input
< MIN_FREQUENCY_UP_THRESHOLD
) {
259 dbs_data
->up_threshold
= input
;
263 static ssize_t
store_sampling_down_factor(struct dbs_data
*dbs_data
,
264 const char *buf
, size_t count
)
266 unsigned int input
, j
;
268 ret
= sscanf(buf
, "%u", &input
);
270 if (ret
!= 1 || input
> MAX_SAMPLING_DOWN_FACTOR
|| input
< 1)
272 dbs_data
->sampling_down_factor
= input
;
274 /* Reset down sampling multiplier in case it was active */
275 for_each_online_cpu(j
) {
276 struct od_cpu_dbs_info_s
*dbs_info
= &per_cpu(od_cpu_dbs_info
,
278 dbs_info
->rate_mult
= 1;
283 static ssize_t
store_ignore_nice_load(struct dbs_data
*dbs_data
,
284 const char *buf
, size_t count
)
286 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
292 ret
= sscanf(buf
, "%u", &input
);
299 if (input
== dbs_data
->ignore_nice_load
) { /* nothing to do */
302 dbs_data
->ignore_nice_load
= input
;
304 /* we need to re-evaluate prev_cpu_idle */
305 for_each_online_cpu(j
) {
306 struct od_cpu_dbs_info_s
*dbs_info
;
307 dbs_info
= &per_cpu(od_cpu_dbs_info
, j
);
308 dbs_info
->cdbs
.prev_cpu_idle
= get_cpu_idle_time(j
,
309 &dbs_info
->cdbs
.prev_cpu_wall
, od_tuners
->io_is_busy
);
310 if (dbs_data
->ignore_nice_load
)
311 dbs_info
->cdbs
.prev_cpu_nice
=
312 kcpustat_cpu(j
).cpustat
[CPUTIME_NICE
];
318 static ssize_t
store_powersave_bias(struct dbs_data
*dbs_data
, const char *buf
,
321 struct od_dbs_tuners
*od_tuners
= dbs_data
->tuners
;
324 ret
= sscanf(buf
, "%u", &input
);
332 od_tuners
->powersave_bias
= input
;
333 ondemand_powersave_bias_init();
337 gov_show_one_common(sampling_rate
);
338 gov_show_one_common(up_threshold
);
339 gov_show_one_common(sampling_down_factor
);
340 gov_show_one_common(ignore_nice_load
);
341 gov_show_one_common(min_sampling_rate
);
342 gov_show_one(od
, io_is_busy
);
343 gov_show_one(od
, powersave_bias
);
345 gov_attr_rw(sampling_rate
);
346 gov_attr_rw(io_is_busy
);
347 gov_attr_rw(up_threshold
);
348 gov_attr_rw(sampling_down_factor
);
349 gov_attr_rw(ignore_nice_load
);
350 gov_attr_rw(powersave_bias
);
351 gov_attr_ro(min_sampling_rate
);
353 static struct attribute
*od_attributes
[] = {
354 &min_sampling_rate
.attr
,
357 &sampling_down_factor
.attr
,
358 &ignore_nice_load
.attr
,
359 &powersave_bias
.attr
,
364 /************************** sysfs end ************************/
366 static int od_init(struct dbs_data
*dbs_data
, bool notify
)
368 struct od_dbs_tuners
*tuners
;
372 tuners
= kzalloc(sizeof(*tuners
), GFP_KERNEL
);
374 pr_err("%s: kzalloc failed\n", __func__
);
379 idle_time
= get_cpu_idle_time_us(cpu
, NULL
);
381 if (idle_time
!= -1ULL) {
382 /* Idle micro accounting is supported. Use finer thresholds */
383 dbs_data
->up_threshold
= MICRO_FREQUENCY_UP_THRESHOLD
;
385 * In nohz/micro accounting case we set the minimum frequency
386 * not depending on HZ, but fixed (very low). The deferred
387 * timer might skip some samples if idle/sleeping as needed.
389 dbs_data
->min_sampling_rate
= MICRO_FREQUENCY_MIN_SAMPLE_RATE
;
391 dbs_data
->up_threshold
= DEF_FREQUENCY_UP_THRESHOLD
;
393 /* For correct statistics, we need 10 ticks for each measure */
394 dbs_data
->min_sampling_rate
= MIN_SAMPLING_RATE_RATIO
*
395 jiffies_to_usecs(10);
398 dbs_data
->sampling_down_factor
= DEF_SAMPLING_DOWN_FACTOR
;
399 dbs_data
->ignore_nice_load
= 0;
400 tuners
->powersave_bias
= default_powersave_bias
;
401 tuners
->io_is_busy
= should_io_be_busy();
403 dbs_data
->tuners
= tuners
;
407 static void od_exit(struct dbs_data
*dbs_data
, bool notify
)
409 kfree(dbs_data
->tuners
);
412 define_get_cpu_dbs_routines(od_cpu_dbs_info
);
414 static struct od_ops od_ops
= {
415 .powersave_bias_init_cpu
= ondemand_powersave_bias_init_cpu
,
416 .powersave_bias_target
= generic_powersave_bias_target
,
417 .freq_increase
= dbs_freq_increase
,
420 static struct dbs_governor od_dbs_gov
= {
423 .governor
= cpufreq_governor_dbs
,
424 .max_transition_latency
= TRANSITION_LATENCY_LIMIT
,
425 .owner
= THIS_MODULE
,
427 .governor
= GOV_ONDEMAND
,
428 .kobj_type
= { .default_attrs
= od_attributes
},
429 .get_cpu_cdbs
= get_cpu_cdbs
,
430 .get_cpu_dbs_info_s
= get_cpu_dbs_info_s
,
431 .gov_dbs_timer
= od_dbs_timer
,
432 .gov_check_cpu
= od_check_cpu
,
438 #define CPU_FREQ_GOV_ONDEMAND (&od_dbs_gov.gov)
440 static void od_set_powersave_bias(unsigned int powersave_bias
)
442 struct cpufreq_policy
*policy
;
443 struct dbs_data
*dbs_data
;
444 struct od_dbs_tuners
*od_tuners
;
448 default_powersave_bias
= powersave_bias
;
449 cpumask_clear(&done
);
452 for_each_online_cpu(cpu
) {
453 struct policy_dbs_info
*policy_dbs
;
455 if (cpumask_test_cpu(cpu
, &done
))
458 policy_dbs
= per_cpu(od_cpu_dbs_info
, cpu
).cdbs
.policy_dbs
;
462 policy
= policy_dbs
->policy
;
463 cpumask_or(&done
, &done
, policy
->cpus
);
465 if (policy
->governor
!= CPU_FREQ_GOV_ONDEMAND
)
468 dbs_data
= policy_dbs
->dbs_data
;
469 od_tuners
= dbs_data
->tuners
;
470 od_tuners
->powersave_bias
= default_powersave_bias
;
475 void od_register_powersave_bias_handler(unsigned int (*f
)
476 (struct cpufreq_policy
*, unsigned int, unsigned int),
477 unsigned int powersave_bias
)
479 od_ops
.powersave_bias_target
= f
;
480 od_set_powersave_bias(powersave_bias
);
482 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler
);
484 void od_unregister_powersave_bias_handler(void)
486 od_ops
.powersave_bias_target
= generic_powersave_bias_target
;
487 od_set_powersave_bias(0);
489 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler
);
491 static int __init
cpufreq_gov_dbs_init(void)
493 return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND
);
496 static void __exit
cpufreq_gov_dbs_exit(void)
498 cpufreq_unregister_governor(CPU_FREQ_GOV_ONDEMAND
);
501 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
502 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
503 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
504 "Low Latency Frequency Transition capable processors");
505 MODULE_LICENSE("GPL");
507 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
508 struct cpufreq_governor
*cpufreq_default_governor(void)
510 return CPU_FREQ_GOV_ONDEMAND
;
513 fs_initcall(cpufreq_gov_dbs_init
);
515 module_init(cpufreq_gov_dbs_init
);
517 module_exit(cpufreq_gov_dbs_exit
);