2 * drivers/cpufreq/cpufreq_conservative.c
4 * Copyright (C) 2001 Russell King
5 * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
6 * Jun Nakajima <jun.nakajima@intel.com>
7 * (C) 2009 Alexander Clouter <alex@digriz.org.uk>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
14 #include <linux/slab.h>
15 #include "cpufreq_governor.h"
17 /* Conservative governor macros */
18 #define DEF_FREQUENCY_UP_THRESHOLD (80)
19 #define DEF_FREQUENCY_DOWN_THRESHOLD (20)
20 #define DEF_FREQUENCY_STEP (5)
21 #define DEF_SAMPLING_DOWN_FACTOR (1)
22 #define MAX_SAMPLING_DOWN_FACTOR (10)
24 static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s
, cs_cpu_dbs_info
);
26 static inline unsigned int get_freq_target(struct cs_dbs_tuners
*cs_tuners
,
27 struct cpufreq_policy
*policy
)
29 unsigned int freq_target
= (cs_tuners
->freq_step
* policy
->max
) / 100;
31 /* max freq cannot be less than 100. But who knows... */
32 if (unlikely(freq_target
== 0))
33 freq_target
= DEF_FREQUENCY_STEP
;
39 * Every sampling_rate, we check, if current idle time is less than 20%
40 * (default), then we try to increase frequency. Every sampling_rate *
41 * sampling_down_factor, we check, if current idle time is more than 80%
42 * (default), then we try to decrease frequency
44 * Any frequency increase takes it to the maximum frequency. Frequency reduction
45 * happens at minimum steps of 5% (default) of maximum frequency
47 static void cs_check_cpu(int cpu
, unsigned int load
)
49 struct cs_cpu_dbs_info_s
*dbs_info
= &per_cpu(cs_cpu_dbs_info
, cpu
);
50 struct cpufreq_policy
*policy
= dbs_info
->cdbs
.cur_policy
;
51 struct dbs_data
*dbs_data
= policy
->governor_data
;
52 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
55 * break out if we 'cannot' reduce the speed as the user might
56 * want freq_step to be zero
58 if (cs_tuners
->freq_step
== 0)
61 /* Check for frequency increase */
62 if (load
> cs_tuners
->up_threshold
) {
63 dbs_info
->down_skip
= 0;
65 /* if we are already at full speed then break out early */
66 if (dbs_info
->requested_freq
== policy
->max
)
69 dbs_info
->requested_freq
+= get_freq_target(cs_tuners
, policy
);
70 if (dbs_info
->requested_freq
> policy
->max
)
71 dbs_info
->requested_freq
= policy
->max
;
73 __cpufreq_driver_target(policy
, dbs_info
->requested_freq
,
78 /* if sampling_down_factor is active break out early */
79 if (++dbs_info
->down_skip
< cs_tuners
->sampling_down_factor
)
81 dbs_info
->down_skip
= 0;
83 /* Check for frequency decrease */
84 if (load
< cs_tuners
->down_threshold
) {
86 * if we cannot reduce the frequency anymore, break out early
88 if (policy
->cur
== policy
->min
)
91 dbs_info
->requested_freq
-= get_freq_target(cs_tuners
, policy
);
92 if (dbs_info
->requested_freq
< policy
->min
)
93 dbs_info
->requested_freq
= policy
->min
;
95 __cpufreq_driver_target(policy
, dbs_info
->requested_freq
,
101 static void cs_dbs_timer(struct work_struct
*work
)
103 struct cs_cpu_dbs_info_s
*dbs_info
= container_of(work
,
104 struct cs_cpu_dbs_info_s
, cdbs
.work
.work
);
105 unsigned int cpu
= dbs_info
->cdbs
.cur_policy
->cpu
;
106 struct cs_cpu_dbs_info_s
*core_dbs_info
= &per_cpu(cs_cpu_dbs_info
,
108 struct dbs_data
*dbs_data
= dbs_info
->cdbs
.cur_policy
->governor_data
;
109 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
110 int delay
= delay_for_sampling_rate(cs_tuners
->sampling_rate
);
111 bool modify_all
= true;
113 mutex_lock(&core_dbs_info
->cdbs
.timer_mutex
);
114 if (!need_load_eval(&core_dbs_info
->cdbs
, cs_tuners
->sampling_rate
))
117 dbs_check_cpu(dbs_data
, cpu
);
119 gov_queue_work(dbs_data
, dbs_info
->cdbs
.cur_policy
, delay
, modify_all
);
120 mutex_unlock(&core_dbs_info
->cdbs
.timer_mutex
);
123 static int dbs_cpufreq_notifier(struct notifier_block
*nb
, unsigned long val
,
126 struct cpufreq_freqs
*freq
= data
;
127 struct cs_cpu_dbs_info_s
*dbs_info
=
128 &per_cpu(cs_cpu_dbs_info
, freq
->cpu
);
129 struct cpufreq_policy
*policy
;
131 if (!dbs_info
->enable
)
134 policy
= dbs_info
->cdbs
.cur_policy
;
137 * we only care if our internally tracked freq moves outside the 'valid'
138 * ranges of frequency available to us otherwise we do not change it
140 if (dbs_info
->requested_freq
> policy
->max
141 || dbs_info
->requested_freq
< policy
->min
)
142 dbs_info
->requested_freq
= freq
->new;
147 /************************** sysfs interface ************************/
148 static struct common_dbs_data cs_dbs_cdata
;
150 static ssize_t
store_sampling_down_factor(struct dbs_data
*dbs_data
,
151 const char *buf
, size_t count
)
153 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
156 ret
= sscanf(buf
, "%u", &input
);
158 if (ret
!= 1 || input
> MAX_SAMPLING_DOWN_FACTOR
|| input
< 1)
161 cs_tuners
->sampling_down_factor
= input
;
165 static ssize_t
store_sampling_rate(struct dbs_data
*dbs_data
, const char *buf
,
168 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
171 ret
= sscanf(buf
, "%u", &input
);
176 cs_tuners
->sampling_rate
= max(input
, dbs_data
->min_sampling_rate
);
180 static ssize_t
store_up_threshold(struct dbs_data
*dbs_data
, const char *buf
,
183 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
186 ret
= sscanf(buf
, "%u", &input
);
188 if (ret
!= 1 || input
> 100 || input
<= cs_tuners
->down_threshold
)
191 cs_tuners
->up_threshold
= input
;
195 static ssize_t
store_down_threshold(struct dbs_data
*dbs_data
, const char *buf
,
198 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
201 ret
= sscanf(buf
, "%u", &input
);
203 /* cannot be lower than 11 otherwise freq will not fall */
204 if (ret
!= 1 || input
< 11 || input
> 100 ||
205 input
>= cs_tuners
->up_threshold
)
208 cs_tuners
->down_threshold
= input
;
212 static ssize_t
store_ignore_nice(struct dbs_data
*dbs_data
, const char *buf
,
215 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
216 unsigned int input
, j
;
219 ret
= sscanf(buf
, "%u", &input
);
226 if (input
== cs_tuners
->ignore_nice
) /* nothing to do */
229 cs_tuners
->ignore_nice
= input
;
231 /* we need to re-evaluate prev_cpu_idle */
232 for_each_online_cpu(j
) {
233 struct cs_cpu_dbs_info_s
*dbs_info
;
234 dbs_info
= &per_cpu(cs_cpu_dbs_info
, j
);
235 dbs_info
->cdbs
.prev_cpu_idle
= get_cpu_idle_time(j
,
236 &dbs_info
->cdbs
.prev_cpu_wall
, 0);
237 if (cs_tuners
->ignore_nice
)
238 dbs_info
->cdbs
.prev_cpu_nice
=
239 kcpustat_cpu(j
).cpustat
[CPUTIME_NICE
];
244 static ssize_t
store_freq_step(struct dbs_data
*dbs_data
, const char *buf
,
247 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
250 ret
= sscanf(buf
, "%u", &input
);
259 * no need to test here if freq_step is zero as the user might actually
260 * want this, they would be crazy though :)
262 cs_tuners
->freq_step
= input
;
266 show_store_one(cs
, sampling_rate
);
267 show_store_one(cs
, sampling_down_factor
);
268 show_store_one(cs
, up_threshold
);
269 show_store_one(cs
, down_threshold
);
270 show_store_one(cs
, ignore_nice
);
271 show_store_one(cs
, freq_step
);
272 declare_show_sampling_rate_min(cs
);
274 gov_sys_pol_attr_rw(sampling_rate
);
275 gov_sys_pol_attr_rw(sampling_down_factor
);
276 gov_sys_pol_attr_rw(up_threshold
);
277 gov_sys_pol_attr_rw(down_threshold
);
278 gov_sys_pol_attr_rw(ignore_nice
);
279 gov_sys_pol_attr_rw(freq_step
);
280 gov_sys_pol_attr_ro(sampling_rate_min
);
282 static struct attribute
*dbs_attributes_gov_sys
[] = {
283 &sampling_rate_min_gov_sys
.attr
,
284 &sampling_rate_gov_sys
.attr
,
285 &sampling_down_factor_gov_sys
.attr
,
286 &up_threshold_gov_sys
.attr
,
287 &down_threshold_gov_sys
.attr
,
288 &ignore_nice_gov_sys
.attr
,
289 &freq_step_gov_sys
.attr
,
293 static struct attribute_group cs_attr_group_gov_sys
= {
294 .attrs
= dbs_attributes_gov_sys
,
295 .name
= "conservative",
298 static struct attribute
*dbs_attributes_gov_pol
[] = {
299 &sampling_rate_min_gov_pol
.attr
,
300 &sampling_rate_gov_pol
.attr
,
301 &sampling_down_factor_gov_pol
.attr
,
302 &up_threshold_gov_pol
.attr
,
303 &down_threshold_gov_pol
.attr
,
304 &ignore_nice_gov_pol
.attr
,
305 &freq_step_gov_pol
.attr
,
309 static struct attribute_group cs_attr_group_gov_pol
= {
310 .attrs
= dbs_attributes_gov_pol
,
311 .name
= "conservative",
314 /************************** sysfs end ************************/
316 static int cs_init(struct dbs_data
*dbs_data
)
318 struct cs_dbs_tuners
*tuners
;
320 tuners
= kzalloc(sizeof(*tuners
), GFP_KERNEL
);
322 pr_err("%s: kzalloc failed\n", __func__
);
326 tuners
->up_threshold
= DEF_FREQUENCY_UP_THRESHOLD
;
327 tuners
->down_threshold
= DEF_FREQUENCY_DOWN_THRESHOLD
;
328 tuners
->sampling_down_factor
= DEF_SAMPLING_DOWN_FACTOR
;
329 tuners
->ignore_nice
= 0;
330 tuners
->freq_step
= DEF_FREQUENCY_STEP
;
332 dbs_data
->tuners
= tuners
;
333 dbs_data
->min_sampling_rate
= MIN_SAMPLING_RATE_RATIO
*
334 jiffies_to_usecs(10);
335 mutex_init(&dbs_data
->mutex
);
339 static void cs_exit(struct dbs_data
*dbs_data
)
341 kfree(dbs_data
->tuners
);
344 define_get_cpu_dbs_routines(cs_cpu_dbs_info
);
346 static struct notifier_block cs_cpufreq_notifier_block
= {
347 .notifier_call
= dbs_cpufreq_notifier
,
350 static struct cs_ops cs_ops
= {
351 .notifier_block
= &cs_cpufreq_notifier_block
,
354 static struct common_dbs_data cs_dbs_cdata
= {
355 .governor
= GOV_CONSERVATIVE
,
356 .attr_group_gov_sys
= &cs_attr_group_gov_sys
,
357 .attr_group_gov_pol
= &cs_attr_group_gov_pol
,
358 .get_cpu_cdbs
= get_cpu_cdbs
,
359 .get_cpu_dbs_info_s
= get_cpu_dbs_info_s
,
360 .gov_dbs_timer
= cs_dbs_timer
,
361 .gov_check_cpu
= cs_check_cpu
,
367 static int cs_cpufreq_governor_dbs(struct cpufreq_policy
*policy
,
370 return cpufreq_governor_dbs(policy
, &cs_dbs_cdata
, event
);
373 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
376 struct cpufreq_governor cpufreq_gov_conservative
= {
377 .name
= "conservative",
378 .governor
= cs_cpufreq_governor_dbs
,
379 .max_transition_latency
= TRANSITION_LATENCY_LIMIT
,
380 .owner
= THIS_MODULE
,
383 static int __init
cpufreq_gov_dbs_init(void)
385 return cpufreq_register_governor(&cpufreq_gov_conservative
);
388 static void __exit
cpufreq_gov_dbs_exit(void)
390 cpufreq_unregister_governor(&cpufreq_gov_conservative
);
393 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
394 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
395 "Low Latency Frequency Transition capable processors "
396 "optimised for use in a battery environment");
397 MODULE_LICENSE("GPL");
399 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
400 fs_initcall(cpufreq_gov_dbs_init
);
402 module_init(cpufreq_gov_dbs_init
);
404 module_exit(cpufreq_gov_dbs_exit
);