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
.shared
->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
);
71 if (dbs_info
->requested_freq
> policy
->max
)
72 dbs_info
->requested_freq
= policy
->max
;
74 __cpufreq_driver_target(policy
, dbs_info
->requested_freq
,
79 /* if sampling_down_factor is active break out early */
80 if (++dbs_info
->down_skip
< cs_tuners
->sampling_down_factor
)
82 dbs_info
->down_skip
= 0;
84 /* Check for frequency decrease */
85 if (load
< cs_tuners
->down_threshold
) {
86 unsigned int freq_target
;
88 * if we cannot reduce the frequency anymore, break out early
90 if (policy
->cur
== policy
->min
)
93 freq_target
= get_freq_target(cs_tuners
, policy
);
94 if (dbs_info
->requested_freq
> freq_target
)
95 dbs_info
->requested_freq
-= freq_target
;
97 dbs_info
->requested_freq
= policy
->min
;
99 __cpufreq_driver_target(policy
, dbs_info
->requested_freq
,
105 static unsigned int cs_dbs_timer(struct cpu_dbs_info
*cdbs
,
106 struct dbs_data
*dbs_data
, bool modify_all
)
108 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
111 dbs_check_cpu(dbs_data
, cdbs
->shared
->policy
->cpu
);
113 return delay_for_sampling_rate(cs_tuners
->sampling_rate
);
116 static int dbs_cpufreq_notifier(struct notifier_block
*nb
, unsigned long val
,
119 struct cpufreq_freqs
*freq
= data
;
120 struct cs_cpu_dbs_info_s
*dbs_info
=
121 &per_cpu(cs_cpu_dbs_info
, freq
->cpu
);
122 struct cpufreq_policy
*policy
;
124 if (!dbs_info
->enable
)
127 policy
= dbs_info
->cdbs
.shared
->policy
;
130 * we only care if our internally tracked freq moves outside the 'valid'
131 * ranges of frequency available to us otherwise we do not change it
133 if (dbs_info
->requested_freq
> policy
->max
134 || dbs_info
->requested_freq
< policy
->min
)
135 dbs_info
->requested_freq
= freq
->new;
140 static struct notifier_block cs_cpufreq_notifier_block
= {
141 .notifier_call
= dbs_cpufreq_notifier
,
144 /************************** sysfs interface ************************/
145 static struct common_dbs_data cs_dbs_cdata
;
147 static ssize_t
store_sampling_down_factor(struct dbs_data
*dbs_data
,
148 const char *buf
, size_t count
)
150 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
153 ret
= sscanf(buf
, "%u", &input
);
155 if (ret
!= 1 || input
> MAX_SAMPLING_DOWN_FACTOR
|| input
< 1)
158 cs_tuners
->sampling_down_factor
= input
;
162 static ssize_t
store_sampling_rate(struct dbs_data
*dbs_data
, const char *buf
,
165 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
168 ret
= sscanf(buf
, "%u", &input
);
173 cs_tuners
->sampling_rate
= max(input
, dbs_data
->min_sampling_rate
);
177 static ssize_t
store_up_threshold(struct dbs_data
*dbs_data
, const char *buf
,
180 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
183 ret
= sscanf(buf
, "%u", &input
);
185 if (ret
!= 1 || input
> 100 || input
<= cs_tuners
->down_threshold
)
188 cs_tuners
->up_threshold
= input
;
192 static ssize_t
store_down_threshold(struct dbs_data
*dbs_data
, const char *buf
,
195 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
198 ret
= sscanf(buf
, "%u", &input
);
200 /* cannot be lower than 11 otherwise freq will not fall */
201 if (ret
!= 1 || input
< 11 || input
> 100 ||
202 input
>= cs_tuners
->up_threshold
)
205 cs_tuners
->down_threshold
= input
;
209 static ssize_t
store_ignore_nice_load(struct dbs_data
*dbs_data
,
210 const char *buf
, size_t count
)
212 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
213 unsigned int input
, j
;
216 ret
= sscanf(buf
, "%u", &input
);
223 if (input
== cs_tuners
->ignore_nice_load
) /* nothing to do */
226 cs_tuners
->ignore_nice_load
= input
;
228 /* we need to re-evaluate prev_cpu_idle */
229 for_each_online_cpu(j
) {
230 struct cs_cpu_dbs_info_s
*dbs_info
;
231 dbs_info
= &per_cpu(cs_cpu_dbs_info
, j
);
232 dbs_info
->cdbs
.prev_cpu_idle
= get_cpu_idle_time(j
,
233 &dbs_info
->cdbs
.prev_cpu_wall
, 0);
234 if (cs_tuners
->ignore_nice_load
)
235 dbs_info
->cdbs
.prev_cpu_nice
=
236 kcpustat_cpu(j
).cpustat
[CPUTIME_NICE
];
241 static ssize_t
store_freq_step(struct dbs_data
*dbs_data
, const char *buf
,
244 struct cs_dbs_tuners
*cs_tuners
= dbs_data
->tuners
;
247 ret
= sscanf(buf
, "%u", &input
);
256 * no need to test here if freq_step is zero as the user might actually
257 * want this, they would be crazy though :)
259 cs_tuners
->freq_step
= input
;
263 show_store_one(cs
, sampling_rate
);
264 show_store_one(cs
, sampling_down_factor
);
265 show_store_one(cs
, up_threshold
);
266 show_store_one(cs
, down_threshold
);
267 show_store_one(cs
, ignore_nice_load
);
268 show_store_one(cs
, freq_step
);
269 declare_show_sampling_rate_min(cs
);
271 gov_sys_pol_attr_rw(sampling_rate
);
272 gov_sys_pol_attr_rw(sampling_down_factor
);
273 gov_sys_pol_attr_rw(up_threshold
);
274 gov_sys_pol_attr_rw(down_threshold
);
275 gov_sys_pol_attr_rw(ignore_nice_load
);
276 gov_sys_pol_attr_rw(freq_step
);
277 gov_sys_pol_attr_ro(sampling_rate_min
);
279 static struct attribute
*dbs_attributes_gov_sys
[] = {
280 &sampling_rate_min_gov_sys
.attr
,
281 &sampling_rate_gov_sys
.attr
,
282 &sampling_down_factor_gov_sys
.attr
,
283 &up_threshold_gov_sys
.attr
,
284 &down_threshold_gov_sys
.attr
,
285 &ignore_nice_load_gov_sys
.attr
,
286 &freq_step_gov_sys
.attr
,
290 static struct attribute_group cs_attr_group_gov_sys
= {
291 .attrs
= dbs_attributes_gov_sys
,
292 .name
= "conservative",
295 static struct attribute
*dbs_attributes_gov_pol
[] = {
296 &sampling_rate_min_gov_pol
.attr
,
297 &sampling_rate_gov_pol
.attr
,
298 &sampling_down_factor_gov_pol
.attr
,
299 &up_threshold_gov_pol
.attr
,
300 &down_threshold_gov_pol
.attr
,
301 &ignore_nice_load_gov_pol
.attr
,
302 &freq_step_gov_pol
.attr
,
306 static struct attribute_group cs_attr_group_gov_pol
= {
307 .attrs
= dbs_attributes_gov_pol
,
308 .name
= "conservative",
311 /************************** sysfs end ************************/
313 static int cs_init(struct dbs_data
*dbs_data
, bool notify
)
315 struct cs_dbs_tuners
*tuners
;
317 tuners
= kzalloc(sizeof(*tuners
), GFP_KERNEL
);
319 pr_err("%s: kzalloc failed\n", __func__
);
323 tuners
->up_threshold
= DEF_FREQUENCY_UP_THRESHOLD
;
324 tuners
->down_threshold
= DEF_FREQUENCY_DOWN_THRESHOLD
;
325 tuners
->sampling_down_factor
= DEF_SAMPLING_DOWN_FACTOR
;
326 tuners
->ignore_nice_load
= 0;
327 tuners
->freq_step
= DEF_FREQUENCY_STEP
;
329 dbs_data
->tuners
= tuners
;
330 dbs_data
->min_sampling_rate
= MIN_SAMPLING_RATE_RATIO
*
331 jiffies_to_usecs(10);
334 cpufreq_register_notifier(&cs_cpufreq_notifier_block
,
335 CPUFREQ_TRANSITION_NOTIFIER
);
340 static void cs_exit(struct dbs_data
*dbs_data
, bool notify
)
343 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block
,
344 CPUFREQ_TRANSITION_NOTIFIER
);
346 kfree(dbs_data
->tuners
);
349 define_get_cpu_dbs_routines(cs_cpu_dbs_info
);
351 static struct common_dbs_data cs_dbs_cdata
= {
352 .governor
= GOV_CONSERVATIVE
,
353 .attr_group_gov_sys
= &cs_attr_group_gov_sys
,
354 .attr_group_gov_pol
= &cs_attr_group_gov_pol
,
355 .get_cpu_cdbs
= get_cpu_cdbs
,
356 .get_cpu_dbs_info_s
= get_cpu_dbs_info_s
,
357 .gov_dbs_timer
= cs_dbs_timer
,
358 .gov_check_cpu
= cs_check_cpu
,
361 .mutex
= __MUTEX_INITIALIZER(cs_dbs_cdata
.mutex
),
364 static int cs_cpufreq_governor_dbs(struct cpufreq_policy
*policy
,
367 return cpufreq_governor_dbs(policy
, &cs_dbs_cdata
, event
);
370 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
373 struct cpufreq_governor cpufreq_gov_conservative
= {
374 .name
= "conservative",
375 .governor
= cs_cpufreq_governor_dbs
,
376 .max_transition_latency
= TRANSITION_LATENCY_LIMIT
,
377 .owner
= THIS_MODULE
,
380 static int __init
cpufreq_gov_dbs_init(void)
382 return cpufreq_register_governor(&cpufreq_gov_conservative
);
385 static void __exit
cpufreq_gov_dbs_exit(void)
387 cpufreq_unregister_governor(&cpufreq_gov_conservative
);
390 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
391 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
392 "Low Latency Frequency Transition capable processors "
393 "optimised for use in a battery environment");
394 MODULE_LICENSE("GPL");
396 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
397 fs_initcall(cpufreq_gov_dbs_init
);
399 module_init(cpufreq_gov_dbs_init
);
401 module_exit(cpufreq_gov_dbs_exit
);