1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
|
/*
* drivers/cpufreq/cpufreq_governor.c
*
* CPUFREQ governors common code
*
* Copyright (C) 2001 Russell King
* (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
* (C) 2003 Jun Nakajima <jun.nakajima@intel.com>
* (C) 2009 Alexander Clouter <alex@digriz.org.uk>
* (c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/export.h>
#include <linux/kernel_stat.h>
#include <linux/slab.h>
#include "cpufreq_governor.h"
DEFINE_MUTEX(dbs_data_mutex);
EXPORT_SYMBOL_GPL(dbs_data_mutex);
static struct attribute_group *get_sysfs_attr(struct dbs_governor *gov)
{
return have_governor_per_policy() ?
gov->attr_group_gov_pol : gov->attr_group_gov_sys;
}
void dbs_check_cpu(struct cpufreq_policy *policy)
{
int cpu = policy->cpu;
struct dbs_governor *gov = dbs_governor_of(policy);
struct policy_dbs_info *policy_dbs = policy->governor_data;
struct dbs_data *dbs_data = policy_dbs->dbs_data;
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
unsigned int sampling_rate;
unsigned int max_load = 0;
unsigned int ignore_nice;
unsigned int j;
if (gov->governor == GOV_ONDEMAND) {
struct od_cpu_dbs_info_s *od_dbs_info =
gov->get_cpu_dbs_info_s(cpu);
/*
* Sometimes, the ondemand governor uses an additional
* multiplier to give long delays. So apply this multiplier to
* the 'sampling_rate', so as to keep the wake-up-from-idle
* detection logic a bit conservative.
*/
sampling_rate = od_tuners->sampling_rate;
sampling_rate *= od_dbs_info->rate_mult;
ignore_nice = od_tuners->ignore_nice_load;
} else {
sampling_rate = cs_tuners->sampling_rate;
ignore_nice = cs_tuners->ignore_nice_load;
}
/* Get Absolute Load */
for_each_cpu(j, policy->cpus) {
struct cpu_dbs_info *j_cdbs;
u64 cur_wall_time, cur_idle_time;
unsigned int idle_time, wall_time;
unsigned int load;
int io_busy = 0;
j_cdbs = gov->get_cpu_cdbs(j);
/*
* For the purpose of ondemand, waiting for disk IO is
* an indication that you're performance critical, and
* not that the system is actually idle. So do not add
* the iowait time to the cpu idle time.
*/
if (gov->governor == GOV_ONDEMAND)
io_busy = od_tuners->io_is_busy;
cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy);
wall_time = (unsigned int)
(cur_wall_time - j_cdbs->prev_cpu_wall);
j_cdbs->prev_cpu_wall = cur_wall_time;
if (cur_idle_time < j_cdbs->prev_cpu_idle)
cur_idle_time = j_cdbs->prev_cpu_idle;
idle_time = (unsigned int)
(cur_idle_time - j_cdbs->prev_cpu_idle);
j_cdbs->prev_cpu_idle = cur_idle_time;
if (ignore_nice) {
struct cpu_dbs_info *cdbs = gov->get_cpu_cdbs(cpu);
u64 cur_nice;
unsigned long cur_nice_jiffies;
cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
cdbs->prev_cpu_nice;
/*
* Assumption: nice time between sampling periods will
* be less than 2^32 jiffies for 32 bit sys
*/
cur_nice_jiffies = (unsigned long)
cputime64_to_jiffies64(cur_nice);
cdbs->prev_cpu_nice =
kcpustat_cpu(j).cpustat[CPUTIME_NICE];
idle_time += jiffies_to_usecs(cur_nice_jiffies);
}
if (unlikely(!wall_time || wall_time < idle_time))
continue;
/*
* If the CPU had gone completely idle, and a task just woke up
* on this CPU now, it would be unfair to calculate 'load' the
* usual way for this elapsed time-window, because it will show
* near-zero load, irrespective of how CPU intensive that task
* actually is. This is undesirable for latency-sensitive bursty
* workloads.
*
* To avoid this, we reuse the 'load' from the previous
* time-window and give this task a chance to start with a
* reasonably high CPU frequency. (However, we shouldn't over-do
* this copy, lest we get stuck at a high load (high frequency)
* for too long, even when the current system load has actually
* dropped down. So we perform the copy only once, upon the
* first wake-up from idle.)
*
* Detecting this situation is easy: the governor's utilization
* update handler would not have run during CPU-idle periods.
* Hence, an unusually large 'wall_time' (as compared to the
* sampling rate) indicates this scenario.
*
* prev_load can be zero in two cases and we must recalculate it
* for both cases:
* - during long idle intervals
* - explicitly set to zero
*/
if (unlikely(wall_time > (2 * sampling_rate) &&
j_cdbs->prev_load)) {
load = j_cdbs->prev_load;
/*
* Perform a destructive copy, to ensure that we copy
* the previous load only once, upon the first wake-up
* from idle.
*/
j_cdbs->prev_load = 0;
} else {
load = 100 * (wall_time - idle_time) / wall_time;
j_cdbs->prev_load = load;
}
if (load > max_load)
max_load = load;
}
gov->gov_check_cpu(cpu, max_load);
}
EXPORT_SYMBOL_GPL(dbs_check_cpu);
void gov_set_update_util(struct policy_dbs_info *policy_dbs,
unsigned int delay_us)
{
struct cpufreq_policy *policy = policy_dbs->policy;
struct dbs_governor *gov = dbs_governor_of(policy);
int cpu;
gov_update_sample_delay(policy_dbs, delay_us);
policy_dbs->last_sample_time = 0;
for_each_cpu(cpu, policy->cpus) {
struct cpu_dbs_info *cdbs = gov->get_cpu_cdbs(cpu);
cpufreq_set_update_util_data(cpu, &cdbs->update_util);
}
}
EXPORT_SYMBOL_GPL(gov_set_update_util);
static inline void gov_clear_update_util(struct cpufreq_policy *policy)
{
int i;
for_each_cpu(i, policy->cpus)
cpufreq_set_update_util_data(i, NULL);
synchronize_rcu();
}
static void gov_cancel_work(struct policy_dbs_info *policy_dbs)
{
/* Tell dbs_update_util_handler() to skip queuing up work items. */
atomic_inc(&policy_dbs->work_count);
/*
* If dbs_update_util_handler() is already running, it may not notice
* the incremented work_count, so wait for it to complete to prevent its
* work item from being queued up after the cancel_work_sync() below.
*/
gov_clear_update_util(policy_dbs->policy);
irq_work_sync(&policy_dbs->irq_work);
cancel_work_sync(&policy_dbs->work);
atomic_set(&policy_dbs->work_count, 0);
}
static void dbs_work_handler(struct work_struct *work)
{
struct policy_dbs_info *policy_dbs;
struct cpufreq_policy *policy;
struct dbs_governor *gov;
unsigned int delay;
policy_dbs = container_of(work, struct policy_dbs_info, work);
policy = policy_dbs->policy;
gov = dbs_governor_of(policy);
/*
* Make sure cpufreq_governor_limits() isn't evaluating load or the
* ondemand governor isn't updating the sampling rate in parallel.
*/
mutex_lock(&policy_dbs->timer_mutex);
delay = gov->gov_dbs_timer(policy);
policy_dbs->sample_delay_ns = jiffies_to_nsecs(delay);
mutex_unlock(&policy_dbs->timer_mutex);
/*
* If the atomic operation below is reordered with respect to the
* sample delay modification, the utilization update handler may end
* up using a stale sample delay value.
*/
smp_mb__before_atomic();
atomic_dec(&policy_dbs->work_count);
}
static void dbs_irq_work(struct irq_work *irq_work)
{
struct policy_dbs_info *policy_dbs;
policy_dbs = container_of(irq_work, struct policy_dbs_info, irq_work);
schedule_work(&policy_dbs->work);
}
static inline void gov_queue_irq_work(struct policy_dbs_info *policy_dbs)
{
#ifdef CONFIG_SMP
irq_work_queue_on(&policy_dbs->irq_work, smp_processor_id());
#else
irq_work_queue(&policy_dbs->irq_work);
#endif
}
static void dbs_update_util_handler(struct update_util_data *data, u64 time,
unsigned long util, unsigned long max)
{
struct cpu_dbs_info *cdbs = container_of(data, struct cpu_dbs_info, update_util);
struct policy_dbs_info *policy_dbs = cdbs->policy_dbs;
/*
* The work may not be allowed to be queued up right now.
* Possible reasons:
* - Work has already been queued up or is in progress.
* - The governor is being stopped.
* - It is too early (too little time from the previous sample).
*/
if (atomic_inc_return(&policy_dbs->work_count) == 1) {
u64 delta_ns;
delta_ns = time - policy_dbs->last_sample_time;
if ((s64)delta_ns >= policy_dbs->sample_delay_ns) {
policy_dbs->last_sample_time = time;
gov_queue_irq_work(policy_dbs);
return;
}
}
atomic_dec(&policy_dbs->work_count);
}
static void set_sampling_rate(struct dbs_data *dbs_data,
struct dbs_governor *gov,
unsigned int sampling_rate)
{
if (gov->governor == GOV_CONSERVATIVE) {
struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
cs_tuners->sampling_rate = sampling_rate;
} else {
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
od_tuners->sampling_rate = sampling_rate;
}
}
static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *policy,
struct dbs_governor *gov)
{
struct policy_dbs_info *policy_dbs;
int j;
/* Allocate memory for the common information for policy->cpus */
policy_dbs = kzalloc(sizeof(*policy_dbs), GFP_KERNEL);
if (!policy_dbs)
return NULL;
mutex_init(&policy_dbs->timer_mutex);
atomic_set(&policy_dbs->work_count, 0);
init_irq_work(&policy_dbs->irq_work, dbs_irq_work);
INIT_WORK(&policy_dbs->work, dbs_work_handler);
/* Set policy_dbs for all CPUs, online+offline */
for_each_cpu(j, policy->related_cpus) {
struct cpu_dbs_info *j_cdbs = gov->get_cpu_cdbs(j);
j_cdbs->policy_dbs = policy_dbs;
j_cdbs->update_util.func = dbs_update_util_handler;
}
return policy_dbs;
}
static void free_policy_dbs_info(struct cpufreq_policy *policy,
struct dbs_governor *gov)
{
struct cpu_dbs_info *cdbs = gov->get_cpu_cdbs(policy->cpu);
struct policy_dbs_info *policy_dbs = cdbs->policy_dbs;
int j;
mutex_destroy(&policy_dbs->timer_mutex);
for_each_cpu(j, policy->related_cpus) {
struct cpu_dbs_info *j_cdbs = gov->get_cpu_cdbs(j);
j_cdbs->policy_dbs = NULL;
j_cdbs->update_util.func = NULL;
}
kfree(policy_dbs);
}
static int cpufreq_governor_init(struct cpufreq_policy *policy)
{
struct dbs_governor *gov = dbs_governor_of(policy);
struct dbs_data *dbs_data = gov->gdbs_data;
struct policy_dbs_info *policy_dbs;
unsigned int latency;
int ret;
/* State should be equivalent to EXIT */
if (policy->governor_data)
return -EBUSY;
policy_dbs = alloc_policy_dbs_info(policy, gov);
if (!policy_dbs)
return -ENOMEM;
if (dbs_data) {
if (WARN_ON(have_governor_per_policy())) {
ret = -EINVAL;
goto free_policy_dbs_info;
}
dbs_data->usage_count++;
policy_dbs->dbs_data = dbs_data;
policy->governor_data = policy_dbs;
return 0;
}
dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
if (!dbs_data) {
ret = -ENOMEM;
goto free_policy_dbs_info;
}
dbs_data->usage_count = 1;
ret = gov->init(dbs_data, !policy->governor->initialized);
if (ret)
goto free_policy_dbs_info;
/* policy latency is in ns. Convert it to us first */
latency = policy->cpuinfo.transition_latency / 1000;
if (latency == 0)
latency = 1;
/* Bring kernel and HW constraints together */
dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
MIN_LATENCY_MULTIPLIER * latency);
set_sampling_rate(dbs_data, gov, max(dbs_data->min_sampling_rate,
latency * LATENCY_MULTIPLIER));
if (!have_governor_per_policy())
gov->gdbs_data = dbs_data;
policy_dbs->dbs_data = dbs_data;
policy->governor_data = policy_dbs;
ret = sysfs_create_group(get_governor_parent_kobj(policy),
get_sysfs_attr(gov));
if (!ret)
return 0;
/* Failure, so roll back. */
policy->governor_data = NULL;
if (!have_governor_per_policy())
gov->gdbs_data = NULL;
gov->exit(dbs_data, !policy->governor->initialized);
kfree(dbs_data);
free_policy_dbs_info:
free_policy_dbs_info(policy, gov);
return ret;
}
static int cpufreq_governor_exit(struct cpufreq_policy *policy)
{
struct dbs_governor *gov = dbs_governor_of(policy);
struct policy_dbs_info *policy_dbs = policy->governor_data;
struct dbs_data *dbs_data = policy_dbs->dbs_data;
/* State should be equivalent to INIT */
if (policy_dbs->policy)
return -EBUSY;
if (!--dbs_data->usage_count) {
sysfs_remove_group(get_governor_parent_kobj(policy),
get_sysfs_attr(gov));
policy->governor_data = NULL;
if (!have_governor_per_policy())
gov->gdbs_data = NULL;
gov->exit(dbs_data, policy->governor->initialized == 1);
kfree(dbs_data);
} else {
policy->governor_data = NULL;
}
free_policy_dbs_info(policy, gov);
return 0;
}
static int cpufreq_governor_start(struct cpufreq_policy *policy)
{
struct dbs_governor *gov = dbs_governor_of(policy);
struct policy_dbs_info *policy_dbs = policy->governor_data;
struct dbs_data *dbs_data = policy_dbs->dbs_data;
unsigned int sampling_rate, ignore_nice, j, cpu = policy->cpu;
int io_busy = 0;
if (!policy->cur)
return -EINVAL;
/* State should be equivalent to INIT */
if (policy_dbs->policy)
return -EBUSY;
if (gov->governor == GOV_CONSERVATIVE) {
struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
sampling_rate = cs_tuners->sampling_rate;
ignore_nice = cs_tuners->ignore_nice_load;
} else {
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
sampling_rate = od_tuners->sampling_rate;
ignore_nice = od_tuners->ignore_nice_load;
io_busy = od_tuners->io_is_busy;
}
for_each_cpu(j, policy->cpus) {
struct cpu_dbs_info *j_cdbs = gov->get_cpu_cdbs(j);
unsigned int prev_load;
j_cdbs->prev_cpu_idle =
get_cpu_idle_time(j, &j_cdbs->prev_cpu_wall, io_busy);
prev_load = (unsigned int)(j_cdbs->prev_cpu_wall -
j_cdbs->prev_cpu_idle);
j_cdbs->prev_load = 100 * prev_load /
(unsigned int)j_cdbs->prev_cpu_wall;
if (ignore_nice)
j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
}
policy_dbs->policy = policy;
if (gov->governor == GOV_CONSERVATIVE) {
struct cs_cpu_dbs_info_s *cs_dbs_info =
gov->get_cpu_dbs_info_s(cpu);
cs_dbs_info->down_skip = 0;
cs_dbs_info->requested_freq = policy->cur;
} else {
struct od_ops *od_ops = gov->gov_ops;
struct od_cpu_dbs_info_s *od_dbs_info = gov->get_cpu_dbs_info_s(cpu);
od_dbs_info->rate_mult = 1;
od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
od_ops->powersave_bias_init_cpu(cpu);
}
gov_set_update_util(policy_dbs, sampling_rate);
return 0;
}
static int cpufreq_governor_stop(struct cpufreq_policy *policy)
{
struct policy_dbs_info *policy_dbs = policy->governor_data;
/* State should be equivalent to START */
if (!policy_dbs->policy)
return -EBUSY;
gov_cancel_work(policy_dbs);
policy_dbs->policy = NULL;
return 0;
}
static int cpufreq_governor_limits(struct cpufreq_policy *policy)
{
struct policy_dbs_info *policy_dbs = policy->governor_data;
/* State should be equivalent to START */
if (!policy_dbs->policy)
return -EBUSY;
mutex_lock(&policy_dbs->timer_mutex);
if (policy->max < policy->cur)
__cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H);
else if (policy->min > policy->cur)
__cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L);
dbs_check_cpu(policy);
mutex_unlock(&policy_dbs->timer_mutex);
return 0;
}
int cpufreq_governor_dbs(struct cpufreq_policy *policy, unsigned int event)
{
int ret = -EINVAL;
/* Lock governor to block concurrent initialization of governor */
mutex_lock(&dbs_data_mutex);
if (event == CPUFREQ_GOV_POLICY_INIT) {
ret = cpufreq_governor_init(policy);
} else if (policy->governor_data) {
switch (event) {
case CPUFREQ_GOV_POLICY_EXIT:
ret = cpufreq_governor_exit(policy);
break;
case CPUFREQ_GOV_START:
ret = cpufreq_governor_start(policy);
break;
case CPUFREQ_GOV_STOP:
ret = cpufreq_governor_stop(policy);
break;
case CPUFREQ_GOV_LIMITS:
ret = cpufreq_governor_limits(policy);
break;
}
}
mutex_unlock(&dbs_data_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);
|