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Dave Jonesb9170832005-05-31 19:03:47 -07001/*
2 * drivers/cpufreq/cpufreq_conservative.c
3 *
4 * Copyright (C) 2001 Russell King
5 * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
6 * Jun Nakajima <jun.nakajima@intel.com>
7 * (C) 2004 Alexander Clouter <alex-kernel@digriz.org.uk>
8 *
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.
12 */
13
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/smp.h>
17#include <linux/init.h>
18#include <linux/interrupt.h>
19#include <linux/ctype.h>
20#include <linux/cpufreq.h>
21#include <linux/sysctl.h>
22#include <linux/types.h>
23#include <linux/fs.h>
24#include <linux/sysfs.h>
Andrew Morton138a01282006-06-23 03:31:19 -070025#include <linux/cpu.h>
Dave Jonesb9170832005-05-31 19:03:47 -070026#include <linux/kmod.h>
27#include <linux/workqueue.h>
28#include <linux/jiffies.h>
29#include <linux/kernel_stat.h>
30#include <linux/percpu.h>
akpm@osdl.org3fc54d32006-01-13 15:54:22 -080031#include <linux/mutex.h>
Dave Jonesb9170832005-05-31 19:03:47 -070032/*
33 * dbs is used in this file as a shortform for demandbased switching
34 * It helps to keep variable names smaller, simpler
35 */
36
37#define DEF_FREQUENCY_UP_THRESHOLD (80)
Dave Jonesb9170832005-05-31 19:03:47 -070038#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
Dave Jonesb9170832005-05-31 19:03:47 -070039
Dave Jones18a72472007-10-22 16:49:09 -040040/*
41 * The polling frequency of this governor depends on the capability of
Dave Jonesb9170832005-05-31 19:03:47 -070042 * the processor. Default polling frequency is 1000 times the transition
Dave Jones18a72472007-10-22 16:49:09 -040043 * latency of the processor. The governor will work on any processor with
44 * transition latency <= 10mS, using appropriate sampling
Dave Jonesb9170832005-05-31 19:03:47 -070045 * rate.
Gautham R Shenoye08f5f52006-10-26 16:20:58 +053046 * For CPUs with transition latency > 10mS (mostly drivers
47 * with CPUFREQ_ETERNAL), this governor will not work.
Dave Jonesb9170832005-05-31 19:03:47 -070048 * All times here are in uS.
49 */
Dave Jones18a72472007-10-22 16:49:09 -040050static unsigned int def_sampling_rate;
Alexander Clouter2c906b32006-03-22 09:54:10 +000051#define MIN_SAMPLING_RATE_RATIO (2)
52/* for correct statistics, we need at least 10 ticks between each measure */
Gautham R Shenoye08f5f52006-10-26 16:20:58 +053053#define MIN_STAT_SAMPLING_RATE \
54 (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
55#define MIN_SAMPLING_RATE \
56 (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
Dave Jonesb9170832005-05-31 19:03:47 -070057#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
Alexander Clouter2c906b32006-03-22 09:54:10 +000058#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000)
59#define DEF_SAMPLING_DOWN_FACTOR (1)
60#define MAX_SAMPLING_DOWN_FACTOR (10)
Thomas Renninger1c256242007-10-02 13:28:12 -070061#define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000)
Dave Jonesb9170832005-05-31 19:03:47 -070062
David Howellsc4028952006-11-22 14:57:56 +000063static void do_dbs_timer(struct work_struct *work);
Dave Jonesb9170832005-05-31 19:03:47 -070064
65struct cpu_dbs_info_s {
Dave Jones18a72472007-10-22 16:49:09 -040066 struct cpufreq_policy *cur_policy;
67 unsigned int prev_cpu_idle_up;
68 unsigned int prev_cpu_idle_down;
69 unsigned int enable;
70 unsigned int down_skip;
71 unsigned int requested_freq;
Dave Jonesb9170832005-05-31 19:03:47 -070072};
73static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
74
75static unsigned int dbs_enable; /* number of CPUs using this policy */
76
Venkatesh Pallipadi4ec223d2006-06-21 15:18:34 -070077/*
78 * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
79 * lock and dbs_mutex. cpu_hotplug lock should always be held before
80 * dbs_mutex. If any function that can potentially take cpu_hotplug lock
81 * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
82 * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
83 * is recursive for the same process. -Venki
84 */
Dave Jones18a72472007-10-22 16:49:09 -040085static DEFINE_MUTEX (dbs_mutex);
David Howellsc4028952006-11-22 14:57:56 +000086static DECLARE_DELAYED_WORK(dbs_work, do_dbs_timer);
Dave Jonesb9170832005-05-31 19:03:47 -070087
88struct dbs_tuners {
Dave Jones18a72472007-10-22 16:49:09 -040089 unsigned int sampling_rate;
90 unsigned int sampling_down_factor;
91 unsigned int up_threshold;
92 unsigned int down_threshold;
93 unsigned int ignore_nice;
94 unsigned int freq_step;
Dave Jonesb9170832005-05-31 19:03:47 -070095};
96
97static struct dbs_tuners dbs_tuners_ins = {
Dave Jones18a72472007-10-22 16:49:09 -040098 .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
99 .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
100 .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
101 .ignore_nice = 0,
102 .freq_step = 5,
Dave Jonesb9170832005-05-31 19:03:47 -0700103};
104
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700105static inline unsigned int get_cpu_idle_time(unsigned int cpu)
106{
Gautham R Shenoye08f5f52006-10-26 16:20:58 +0530107 unsigned int add_nice = 0, ret;
108
109 if (dbs_tuners_ins.ignore_nice)
110 add_nice = kstat_cpu(cpu).cpustat.nice;
111
Dave Jones18a72472007-10-22 16:49:09 -0400112 ret = kstat_cpu(cpu).cpustat.idle +
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700113 kstat_cpu(cpu).cpustat.iowait +
Gautham R Shenoye08f5f52006-10-26 16:20:58 +0530114 add_nice;
115
116 return ret;
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700117}
118
Elias Oltmannsa8d7c3b2007-10-22 09:50:13 +0200119/* keep track of frequency transitions */
120static int
121dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
122 void *data)
123{
124 struct cpufreq_freqs *freq = data;
125 struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info,
126 freq->cpu);
127
128 if (!this_dbs_info->enable)
129 return 0;
130
131 this_dbs_info->requested_freq = freq->new;
132
133 return 0;
134}
135
136static struct notifier_block dbs_cpufreq_notifier_block = {
137 .notifier_call = dbs_cpufreq_notifier
138};
139
Dave Jonesb9170832005-05-31 19:03:47 -0700140/************************** sysfs interface ************************/
141static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
142{
143 return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
144}
145
146static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
147{
148 return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
149}
150
Dave Jones18a72472007-10-22 16:49:09 -0400151#define define_one_ro(_name) \
152static struct freq_attr _name = \
Dave Jonesb9170832005-05-31 19:03:47 -0700153__ATTR(_name, 0444, show_##_name, NULL)
154
155define_one_ro(sampling_rate_max);
156define_one_ro(sampling_rate_min);
157
158/* cpufreq_conservative Governor Tunables */
159#define show_one(file_name, object) \
160static ssize_t show_##file_name \
161(struct cpufreq_policy *unused, char *buf) \
162{ \
163 return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
164}
165show_one(sampling_rate, sampling_rate);
166show_one(sampling_down_factor, sampling_down_factor);
167show_one(up_threshold, up_threshold);
168show_one(down_threshold, down_threshold);
Alexander Clouter001893c2005-12-01 01:09:25 -0800169show_one(ignore_nice_load, ignore_nice);
Dave Jonesb9170832005-05-31 19:03:47 -0700170show_one(freq_step, freq_step);
171
Dave Jones18a72472007-10-22 16:49:09 -0400172static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
Dave Jonesb9170832005-05-31 19:03:47 -0700173 const char *buf, size_t count)
174{
175 unsigned int input;
176 int ret;
177 ret = sscanf (buf, "%u", &input);
Alexander Clouter2c906b32006-03-22 09:54:10 +0000178 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
Dave Jonesb9170832005-05-31 19:03:47 -0700179 return -EINVAL;
180
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800181 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700182 dbs_tuners_ins.sampling_down_factor = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800183 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700184
185 return count;
186}
187
Dave Jones18a72472007-10-22 16:49:09 -0400188static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
Dave Jonesb9170832005-05-31 19:03:47 -0700189 const char *buf, size_t count)
190{
191 unsigned int input;
192 int ret;
193 ret = sscanf (buf, "%u", &input);
194
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800195 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700196 if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800197 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700198 return -EINVAL;
199 }
200
201 dbs_tuners_ins.sampling_rate = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800202 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700203
204 return count;
205}
206
Dave Jones18a72472007-10-22 16:49:09 -0400207static ssize_t store_up_threshold(struct cpufreq_policy *unused,
Dave Jonesb9170832005-05-31 19:03:47 -0700208 const char *buf, size_t count)
209{
210 unsigned int input;
211 int ret;
212 ret = sscanf (buf, "%u", &input);
213
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800214 mutex_lock(&dbs_mutex);
Dave Jonesb82fbe62006-04-01 22:07:07 -0500215 if (ret != 1 || input > 100 || input <= dbs_tuners_ins.down_threshold) {
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800216 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700217 return -EINVAL;
218 }
219
220 dbs_tuners_ins.up_threshold = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800221 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700222
223 return count;
224}
225
Dave Jones18a72472007-10-22 16:49:09 -0400226static ssize_t store_down_threshold(struct cpufreq_policy *unused,
Dave Jonesb9170832005-05-31 19:03:47 -0700227 const char *buf, size_t count)
228{
229 unsigned int input;
230 int ret;
231 ret = sscanf (buf, "%u", &input);
232
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800233 mutex_lock(&dbs_mutex);
Dave Jonesb82fbe62006-04-01 22:07:07 -0500234 if (ret != 1 || input > 100 || input >= dbs_tuners_ins.up_threshold) {
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800235 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700236 return -EINVAL;
237 }
238
239 dbs_tuners_ins.down_threshold = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800240 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700241
242 return count;
243}
244
Alexander Clouter001893c2005-12-01 01:09:25 -0800245static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
Dave Jonesb9170832005-05-31 19:03:47 -0700246 const char *buf, size_t count)
247{
248 unsigned int input;
249 int ret;
250
251 unsigned int j;
Dave Jones18a72472007-10-22 16:49:09 -0400252
253 ret = sscanf(buf, "%u", &input);
254 if (ret != 1)
Dave Jonesb9170832005-05-31 19:03:47 -0700255 return -EINVAL;
256
Dave Jones18a72472007-10-22 16:49:09 -0400257 if (input > 1)
Dave Jonesb9170832005-05-31 19:03:47 -0700258 input = 1;
Dave Jones18a72472007-10-22 16:49:09 -0400259
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800260 mutex_lock(&dbs_mutex);
Dave Jones18a72472007-10-22 16:49:09 -0400261 if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800262 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700263 return count;
264 }
265 dbs_tuners_ins.ignore_nice = input;
266
267 /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700268 for_each_online_cpu(j) {
Dave Jonesb9170832005-05-31 19:03:47 -0700269 struct cpu_dbs_info_s *j_dbs_info;
270 j_dbs_info = &per_cpu(cpu_dbs_info, j);
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700271 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
Dave Jonesb9170832005-05-31 19:03:47 -0700272 j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
273 }
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800274 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700275
276 return count;
277}
278
279static ssize_t store_freq_step(struct cpufreq_policy *policy,
280 const char *buf, size_t count)
281{
282 unsigned int input;
283 int ret;
284
Dave Jones18a72472007-10-22 16:49:09 -0400285 ret = sscanf(buf, "%u", &input);
Dave Jonesb9170832005-05-31 19:03:47 -0700286
Dave Jones18a72472007-10-22 16:49:09 -0400287 if (ret != 1)
Dave Jonesb9170832005-05-31 19:03:47 -0700288 return -EINVAL;
289
Dave Jones18a72472007-10-22 16:49:09 -0400290 if (input > 100)
Dave Jonesb9170832005-05-31 19:03:47 -0700291 input = 100;
Dave Jones18a72472007-10-22 16:49:09 -0400292
Dave Jonesb9170832005-05-31 19:03:47 -0700293 /* no need to test here if freq_step is zero as the user might actually
294 * want this, they would be crazy though :) */
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800295 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700296 dbs_tuners_ins.freq_step = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800297 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700298
299 return count;
300}
301
302#define define_one_rw(_name) \
303static struct freq_attr _name = \
304__ATTR(_name, 0644, show_##_name, store_##_name)
305
306define_one_rw(sampling_rate);
307define_one_rw(sampling_down_factor);
308define_one_rw(up_threshold);
309define_one_rw(down_threshold);
Alexander Clouter001893c2005-12-01 01:09:25 -0800310define_one_rw(ignore_nice_load);
Dave Jonesb9170832005-05-31 19:03:47 -0700311define_one_rw(freq_step);
312
313static struct attribute * dbs_attributes[] = {
314 &sampling_rate_max.attr,
315 &sampling_rate_min.attr,
316 &sampling_rate.attr,
317 &sampling_down_factor.attr,
318 &up_threshold.attr,
319 &down_threshold.attr,
Alexander Clouter001893c2005-12-01 01:09:25 -0800320 &ignore_nice_load.attr,
Dave Jonesb9170832005-05-31 19:03:47 -0700321 &freq_step.attr,
322 NULL
323};
324
325static struct attribute_group dbs_attr_group = {
326 .attrs = dbs_attributes,
327 .name = "conservative",
328};
329
330/************************** sysfs end ************************/
331
332static void dbs_check_cpu(int cpu)
333{
334 unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
Alexander Clouter08a28e22006-03-22 09:59:16 +0000335 unsigned int tmp_idle_ticks, total_idle_ticks;
Dave Jonesf068c042008-07-30 12:59:56 -0400336 unsigned int freq_target;
Dave Jonesb9170832005-05-31 19:03:47 -0700337 unsigned int freq_down_sampling_rate;
Alexander Clouter08a28e22006-03-22 09:59:16 +0000338 struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
Dave Jonesb9170832005-05-31 19:03:47 -0700339 struct cpufreq_policy *policy;
Dave Jonesb9170832005-05-31 19:03:47 -0700340
Dave Jonesb9170832005-05-31 19:03:47 -0700341 if (!this_dbs_info->enable)
342 return;
343
Alexander Clouter08a28e22006-03-22 09:59:16 +0000344 policy = this_dbs_info->cur_policy;
345
Dave Jones18a72472007-10-22 16:49:09 -0400346 /*
347 * The default safe range is 20% to 80%
Dave Jonesb9170832005-05-31 19:03:47 -0700348 * Every sampling_rate, we check
Dave Jones18a72472007-10-22 16:49:09 -0400349 * - If current idle time is less than 20%, then we try to
350 * increase frequency
Dave Jonesb9170832005-05-31 19:03:47 -0700351 * Every sampling_rate*sampling_down_factor, we check
Dave Jones18a72472007-10-22 16:49:09 -0400352 * - If current idle time is more than 80%, then we try to
353 * decrease frequency
Dave Jonesb9170832005-05-31 19:03:47 -0700354 *
Dave Jones18a72472007-10-22 16:49:09 -0400355 * Any frequency increase takes it to the maximum frequency.
356 * Frequency reduction happens at minimum steps of
357 * 5% (default) of max_frequency
Dave Jonesb9170832005-05-31 19:03:47 -0700358 */
359
360 /* Check for frequency increase */
Dave Jones9c7d2692005-05-31 19:03:49 -0700361 idle_ticks = UINT_MAX;
Dave Jonesb9170832005-05-31 19:03:47 -0700362
Alexander Clouter08a28e22006-03-22 09:59:16 +0000363 /* Check for frequency increase */
364 total_idle_ticks = get_cpu_idle_time(cpu);
365 tmp_idle_ticks = total_idle_ticks -
366 this_dbs_info->prev_cpu_idle_up;
367 this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700368
Alexander Clouter08a28e22006-03-22 09:59:16 +0000369 if (tmp_idle_ticks < idle_ticks)
370 idle_ticks = tmp_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700371
372 /* Scale idle ticks by 100 and compare with up and down ticks */
373 idle_ticks *= 100;
374 up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
Alexander Clouter2c906b32006-03-22 09:54:10 +0000375 usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
Dave Jonesb9170832005-05-31 19:03:47 -0700376
377 if (idle_ticks < up_idle_ticks) {
Alexander Cloutera159b822006-03-22 10:00:18 +0000378 this_dbs_info->down_skip = 0;
Alexander Clouter08a28e22006-03-22 09:59:16 +0000379 this_dbs_info->prev_cpu_idle_down =
380 this_dbs_info->prev_cpu_idle_up;
Dave Jones790d76f2005-05-31 19:03:49 -0700381
Dave Jonesb9170832005-05-31 19:03:47 -0700382 /* if we are already at full speed then break out early */
Alexander Cloutera159b822006-03-22 10:00:18 +0000383 if (this_dbs_info->requested_freq == policy->max)
Dave Jonesb9170832005-05-31 19:03:47 -0700384 return;
Dave Jones18a72472007-10-22 16:49:09 -0400385
Dave Jonesf068c042008-07-30 12:59:56 -0400386 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
Dave Jonesb9170832005-05-31 19:03:47 -0700387
388 /* max freq cannot be less than 100. But who knows.... */
Dave Jonesf068c042008-07-30 12:59:56 -0400389 if (unlikely(freq_target == 0))
390 freq_target = 5;
Dave Jones18a72472007-10-22 16:49:09 -0400391
Dave Jonesf068c042008-07-30 12:59:56 -0400392 this_dbs_info->requested_freq += freq_target;
Alexander Cloutera159b822006-03-22 10:00:18 +0000393 if (this_dbs_info->requested_freq > policy->max)
394 this_dbs_info->requested_freq = policy->max;
Dave Jonesb9170832005-05-31 19:03:47 -0700395
Alexander Cloutera159b822006-03-22 10:00:18 +0000396 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
Dave Jonesb9170832005-05-31 19:03:47 -0700397 CPUFREQ_RELATION_H);
Dave Jonesb9170832005-05-31 19:03:47 -0700398 return;
399 }
400
401 /* Check for frequency decrease */
Alexander Cloutera159b822006-03-22 10:00:18 +0000402 this_dbs_info->down_skip++;
403 if (this_dbs_info->down_skip < dbs_tuners_ins.sampling_down_factor)
Dave Jonesb9170832005-05-31 19:03:47 -0700404 return;
405
Alexander Clouter08a28e22006-03-22 09:59:16 +0000406 /* Check for frequency decrease */
407 total_idle_ticks = this_dbs_info->prev_cpu_idle_up;
408 tmp_idle_ticks = total_idle_ticks -
409 this_dbs_info->prev_cpu_idle_down;
410 this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700411
Alexander Clouter08a28e22006-03-22 09:59:16 +0000412 if (tmp_idle_ticks < idle_ticks)
413 idle_ticks = tmp_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700414
415 /* Scale idle ticks by 100 and compare with up and down ticks */
416 idle_ticks *= 100;
Alexander Cloutera159b822006-03-22 10:00:18 +0000417 this_dbs_info->down_skip = 0;
Dave Jonesb9170832005-05-31 19:03:47 -0700418
419 freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
420 dbs_tuners_ins.sampling_down_factor;
421 down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
Alexander Clouter2c906b32006-03-22 09:54:10 +0000422 usecs_to_jiffies(freq_down_sampling_rate);
Dave Jonesb9170832005-05-31 19:03:47 -0700423
Dave Jones9c7d2692005-05-31 19:03:49 -0700424 if (idle_ticks > down_idle_ticks) {
Alexander Clouter2c906b32006-03-22 09:54:10 +0000425 /*
426 * if we are already at the lowest speed then break out early
Dave Jonesb9170832005-05-31 19:03:47 -0700427 * or if we 'cannot' reduce the speed as the user might want
Dave Jonesf068c042008-07-30 12:59:56 -0400428 * freq_target to be zero
Alexander Clouter2c906b32006-03-22 09:54:10 +0000429 */
Alexander Cloutera159b822006-03-22 10:00:18 +0000430 if (this_dbs_info->requested_freq == policy->min
Dave Jonesb9170832005-05-31 19:03:47 -0700431 || dbs_tuners_ins.freq_step == 0)
432 return;
433
Dave Jonesf068c042008-07-30 12:59:56 -0400434 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
Dave Jonesb9170832005-05-31 19:03:47 -0700435
436 /* max freq cannot be less than 100. But who knows.... */
Dave Jonesf068c042008-07-30 12:59:56 -0400437 if (unlikely(freq_target == 0))
438 freq_target = 5;
Dave Jonesb9170832005-05-31 19:03:47 -0700439
Dave Jonesf068c042008-07-30 12:59:56 -0400440 this_dbs_info->requested_freq -= freq_target;
Alexander Cloutera159b822006-03-22 10:00:18 +0000441 if (this_dbs_info->requested_freq < policy->min)
442 this_dbs_info->requested_freq = policy->min;
Dave Jonesb9170832005-05-31 19:03:47 -0700443
Alexander Cloutera159b822006-03-22 10:00:18 +0000444 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
Alexander Clouter2c906b32006-03-22 09:54:10 +0000445 CPUFREQ_RELATION_H);
Dave Jonesb9170832005-05-31 19:03:47 -0700446 return;
447 }
448}
449
David Howellsc4028952006-11-22 14:57:56 +0000450static void do_dbs_timer(struct work_struct *work)
Dave Jones18a72472007-10-22 16:49:09 -0400451{
Dave Jonesb9170832005-05-31 19:03:47 -0700452 int i;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800453 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700454 for_each_online_cpu(i)
455 dbs_check_cpu(i);
Dave Jones18a72472007-10-22 16:49:09 -0400456 schedule_delayed_work(&dbs_work,
Dave Jonesb9170832005-05-31 19:03:47 -0700457 usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800458 mutex_unlock(&dbs_mutex);
Dave Jones18a72472007-10-22 16:49:09 -0400459}
Dave Jonesb9170832005-05-31 19:03:47 -0700460
461static inline void dbs_timer_init(void)
462{
Ben Slusky8217e4f2008-07-07 13:16:20 -0400463 init_timer_deferrable(&dbs_work.timer);
Dave Jonesb9170832005-05-31 19:03:47 -0700464 schedule_delayed_work(&dbs_work,
465 usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
466 return;
467}
468
469static inline void dbs_timer_exit(void)
470{
471 cancel_delayed_work(&dbs_work);
472 return;
473}
474
475static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
476 unsigned int event)
477{
478 unsigned int cpu = policy->cpu;
479 struct cpu_dbs_info_s *this_dbs_info;
480 unsigned int j;
Jeff Garzik914f7c32006-10-20 14:31:00 -0700481 int rc;
Dave Jonesb9170832005-05-31 19:03:47 -0700482
483 this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
484
485 switch (event) {
486 case CPUFREQ_GOV_START:
Dave Jones18a72472007-10-22 16:49:09 -0400487 if ((!cpu_online(cpu)) || (!policy->cur))
Dave Jonesb9170832005-05-31 19:03:47 -0700488 return -EINVAL;
489
Dave Jonesb9170832005-05-31 19:03:47 -0700490 if (this_dbs_info->enable) /* Already enabled */
491 break;
Dave Jones18a72472007-10-22 16:49:09 -0400492
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800493 mutex_lock(&dbs_mutex);
Jeff Garzik914f7c32006-10-20 14:31:00 -0700494
495 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
496 if (rc) {
497 mutex_unlock(&dbs_mutex);
498 return rc;
499 }
500
Mike Travis068b1272008-05-12 21:21:13 +0200501 for_each_cpu_mask_nr(j, policy->cpus) {
Dave Jonesb9170832005-05-31 19:03:47 -0700502 struct cpu_dbs_info_s *j_dbs_info;
503 j_dbs_info = &per_cpu(cpu_dbs_info, j);
504 j_dbs_info->cur_policy = policy;
Dave Jones18a72472007-10-22 16:49:09 -0400505
Alexander Clouter08a28e22006-03-22 09:59:16 +0000506 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(cpu);
Dave Jonesb9170832005-05-31 19:03:47 -0700507 j_dbs_info->prev_cpu_idle_down
508 = j_dbs_info->prev_cpu_idle_up;
509 }
510 this_dbs_info->enable = 1;
Alexander Cloutera159b822006-03-22 10:00:18 +0000511 this_dbs_info->down_skip = 0;
512 this_dbs_info->requested_freq = policy->cur;
Jeff Garzik914f7c32006-10-20 14:31:00 -0700513
Dave Jonesb9170832005-05-31 19:03:47 -0700514 dbs_enable++;
515 /*
516 * Start the timerschedule work, when this governor
517 * is used for first time
518 */
519 if (dbs_enable == 1) {
520 unsigned int latency;
521 /* policy latency is in nS. Convert it to uS first */
Alexander Clouter2c906b32006-03-22 09:54:10 +0000522 latency = policy->cpuinfo.transition_latency / 1000;
523 if (latency == 0)
524 latency = 1;
Dave Jonesb9170832005-05-31 19:03:47 -0700525
Alexander Cloutere8a02572006-03-22 09:56:23 +0000526 def_sampling_rate = 10 * latency *
Dave Jonesb9170832005-05-31 19:03:47 -0700527 DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
Alexander Clouter2c906b32006-03-22 09:54:10 +0000528
529 if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
530 def_sampling_rate = MIN_STAT_SAMPLING_RATE;
531
Dave Jonesb9170832005-05-31 19:03:47 -0700532 dbs_tuners_ins.sampling_rate = def_sampling_rate;
Dave Jonesb9170832005-05-31 19:03:47 -0700533
534 dbs_timer_init();
Elias Oltmannsa8d7c3b2007-10-22 09:50:13 +0200535 cpufreq_register_notifier(
536 &dbs_cpufreq_notifier_block,
537 CPUFREQ_TRANSITION_NOTIFIER);
Dave Jonesb9170832005-05-31 19:03:47 -0700538 }
Dave Jones18a72472007-10-22 16:49:09 -0400539
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800540 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700541 break;
542
543 case CPUFREQ_GOV_STOP:
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800544 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700545 this_dbs_info->enable = 0;
546 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
547 dbs_enable--;
548 /*
549 * Stop the timerschedule work, when this governor
550 * is used for first time
551 */
Elias Oltmannsa8d7c3b2007-10-22 09:50:13 +0200552 if (dbs_enable == 0) {
Dave Jonesb9170832005-05-31 19:03:47 -0700553 dbs_timer_exit();
Elias Oltmannsa8d7c3b2007-10-22 09:50:13 +0200554 cpufreq_unregister_notifier(
555 &dbs_cpufreq_notifier_block,
556 CPUFREQ_TRANSITION_NOTIFIER);
557 }
558
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800559 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700560
561 break;
562
563 case CPUFREQ_GOV_LIMITS:
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800564 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700565 if (policy->max < this_dbs_info->cur_policy->cur)
566 __cpufreq_driver_target(
567 this_dbs_info->cur_policy,
Dave Jones18a72472007-10-22 16:49:09 -0400568 policy->max, CPUFREQ_RELATION_H);
Dave Jonesb9170832005-05-31 19:03:47 -0700569 else if (policy->min > this_dbs_info->cur_policy->cur)
570 __cpufreq_driver_target(
571 this_dbs_info->cur_policy,
Dave Jones18a72472007-10-22 16:49:09 -0400572 policy->min, CPUFREQ_RELATION_L);
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800573 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700574 break;
575 }
576 return 0;
577}
578
Sven Wegenerc4d14bc2008-09-20 16:50:08 +0200579#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
580static
581#endif
Thomas Renninger1c256242007-10-02 13:28:12 -0700582struct cpufreq_governor cpufreq_gov_conservative = {
583 .name = "conservative",
584 .governor = cpufreq_governor_dbs,
585 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
586 .owner = THIS_MODULE,
Dave Jonesb9170832005-05-31 19:03:47 -0700587};
588
589static int __init cpufreq_gov_dbs_init(void)
590{
Thomas Renninger1c256242007-10-02 13:28:12 -0700591 return cpufreq_register_governor(&cpufreq_gov_conservative);
Dave Jonesb9170832005-05-31 19:03:47 -0700592}
593
594static void __exit cpufreq_gov_dbs_exit(void)
595{
596 /* Make sure that the scheduled work is indeed not running */
597 flush_scheduled_work();
598
Thomas Renninger1c256242007-10-02 13:28:12 -0700599 cpufreq_unregister_governor(&cpufreq_gov_conservative);
Dave Jonesb9170832005-05-31 19:03:47 -0700600}
601
602
603MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>");
604MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
605 "Low Latency Frequency Transition capable processors "
606 "optimised for use in a battery environment");
607MODULE_LICENSE ("GPL");
608
Johannes Weiner69157192008-01-17 15:21:08 -0800609#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
610fs_initcall(cpufreq_gov_dbs_init);
611#else
Dave Jonesb9170832005-05-31 19:03:47 -0700612module_init(cpufreq_gov_dbs_init);
Johannes Weiner69157192008-01-17 15:21:08 -0800613#endif
Dave Jonesb9170832005-05-31 19:03:47 -0700614module_exit(cpufreq_gov_dbs_exit);