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4f86d3a8 LB |
1 | /* |
2 | * menu.c - the menu idle governor | |
3 | * | |
4 | * Copyright (C) 2006-2007 Adam Belay <abelay@novell.com> | |
69d25870 AV |
5 | * Copyright (C) 2009 Intel Corporation |
6 | * Author: | |
7 | * Arjan van de Ven <arjan@linux.intel.com> | |
4f86d3a8 | 8 | * |
69d25870 AV |
9 | * This code is licenced under the GPL version 2 as described |
10 | * in the COPYING file that acompanies the Linux Kernel. | |
4f86d3a8 LB |
11 | */ |
12 | ||
13 | #include <linux/kernel.h> | |
14 | #include <linux/cpuidle.h> | |
e8db0be1 | 15 | #include <linux/pm_qos.h> |
4f86d3a8 LB |
16 | #include <linux/time.h> |
17 | #include <linux/ktime.h> | |
18 | #include <linux/hrtimer.h> | |
19 | #include <linux/tick.h> | |
69d25870 | 20 | #include <linux/sched.h> |
5787536e | 21 | #include <linux/math64.h> |
884b17e1 | 22 | #include <linux/module.h> |
4f86d3a8 | 23 | |
69d25870 | 24 | #define BUCKETS 12 |
1f85f87d | 25 | #define INTERVALS 8 |
69d25870 | 26 | #define RESOLUTION 1024 |
1f85f87d | 27 | #define DECAY 8 |
69d25870 | 28 | #define MAX_INTERESTING 50000 |
1f85f87d AV |
29 | #define STDDEV_THRESH 400 |
30 | ||
69a37bea YS |
31 | /* 60 * 60 > STDDEV_THRESH * INTERVALS = 400 * 8 */ |
32 | #define MAX_DEVIATION 60 | |
33 | ||
34 | static DEFINE_PER_CPU(struct hrtimer, menu_hrtimer); | |
35 | static DEFINE_PER_CPU(int, hrtimer_status); | |
36 | /* menu hrtimer mode */ | |
e11538d1 | 37 | enum {MENU_HRTIMER_STOP, MENU_HRTIMER_REPEAT, MENU_HRTIMER_GENERAL}; |
69d25870 AV |
38 | |
39 | /* | |
40 | * Concepts and ideas behind the menu governor | |
41 | * | |
42 | * For the menu governor, there are 3 decision factors for picking a C | |
43 | * state: | |
44 | * 1) Energy break even point | |
45 | * 2) Performance impact | |
46 | * 3) Latency tolerance (from pmqos infrastructure) | |
47 | * These these three factors are treated independently. | |
48 | * | |
49 | * Energy break even point | |
50 | * ----------------------- | |
51 | * C state entry and exit have an energy cost, and a certain amount of time in | |
52 | * the C state is required to actually break even on this cost. CPUIDLE | |
53 | * provides us this duration in the "target_residency" field. So all that we | |
54 | * need is a good prediction of how long we'll be idle. Like the traditional | |
55 | * menu governor, we start with the actual known "next timer event" time. | |
56 | * | |
57 | * Since there are other source of wakeups (interrupts for example) than | |
58 | * the next timer event, this estimation is rather optimistic. To get a | |
59 | * more realistic estimate, a correction factor is applied to the estimate, | |
60 | * that is based on historic behavior. For example, if in the past the actual | |
61 | * duration always was 50% of the next timer tick, the correction factor will | |
62 | * be 0.5. | |
63 | * | |
64 | * menu uses a running average for this correction factor, however it uses a | |
65 | * set of factors, not just a single factor. This stems from the realization | |
66 | * that the ratio is dependent on the order of magnitude of the expected | |
67 | * duration; if we expect 500 milliseconds of idle time the likelihood of | |
68 | * getting an interrupt very early is much higher than if we expect 50 micro | |
69 | * seconds of idle time. A second independent factor that has big impact on | |
70 | * the actual factor is if there is (disk) IO outstanding or not. | |
71 | * (as a special twist, we consider every sleep longer than 50 milliseconds | |
72 | * as perfect; there are no power gains for sleeping longer than this) | |
73 | * | |
74 | * For these two reasons we keep an array of 12 independent factors, that gets | |
75 | * indexed based on the magnitude of the expected duration as well as the | |
76 | * "is IO outstanding" property. | |
77 | * | |
1f85f87d AV |
78 | * Repeatable-interval-detector |
79 | * ---------------------------- | |
80 | * There are some cases where "next timer" is a completely unusable predictor: | |
81 | * Those cases where the interval is fixed, for example due to hardware | |
82 | * interrupt mitigation, but also due to fixed transfer rate devices such as | |
83 | * mice. | |
84 | * For this, we use a different predictor: We track the duration of the last 8 | |
85 | * intervals and if the stand deviation of these 8 intervals is below a | |
86 | * threshold value, we use the average of these intervals as prediction. | |
87 | * | |
69d25870 AV |
88 | * Limiting Performance Impact |
89 | * --------------------------- | |
90 | * C states, especially those with large exit latencies, can have a real | |
20e3341b | 91 | * noticeable impact on workloads, which is not acceptable for most sysadmins, |
69d25870 AV |
92 | * and in addition, less performance has a power price of its own. |
93 | * | |
94 | * As a general rule of thumb, menu assumes that the following heuristic | |
95 | * holds: | |
96 | * The busier the system, the less impact of C states is acceptable | |
97 | * | |
98 | * This rule-of-thumb is implemented using a performance-multiplier: | |
99 | * If the exit latency times the performance multiplier is longer than | |
100 | * the predicted duration, the C state is not considered a candidate | |
101 | * for selection due to a too high performance impact. So the higher | |
102 | * this multiplier is, the longer we need to be idle to pick a deep C | |
103 | * state, and thus the less likely a busy CPU will hit such a deep | |
104 | * C state. | |
105 | * | |
106 | * Two factors are used in determing this multiplier: | |
107 | * a value of 10 is added for each point of "per cpu load average" we have. | |
108 | * a value of 5 points is added for each process that is waiting for | |
109 | * IO on this CPU. | |
110 | * (these values are experimentally determined) | |
111 | * | |
112 | * The load average factor gives a longer term (few seconds) input to the | |
113 | * decision, while the iowait value gives a cpu local instantanious input. | |
114 | * The iowait factor may look low, but realize that this is also already | |
115 | * represented in the system load average. | |
116 | * | |
117 | */ | |
4f86d3a8 | 118 | |
e11538d1 YS |
119 | /* |
120 | * The C-state residency is so long that is is worthwhile to exit | |
121 | * from the shallow C-state and re-enter into a deeper C-state. | |
122 | */ | |
123 | static unsigned int perfect_cstate_ms __read_mostly = 30; | |
124 | module_param(perfect_cstate_ms, uint, 0000); | |
125 | ||
4f86d3a8 LB |
126 | struct menu_device { |
127 | int last_state_idx; | |
672917dc | 128 | int needs_update; |
4f86d3a8 LB |
129 | |
130 | unsigned int expected_us; | |
56e6943b | 131 | u64 predicted_us; |
69d25870 AV |
132 | unsigned int exit_us; |
133 | unsigned int bucket; | |
134 | u64 correction_factor[BUCKETS]; | |
1f85f87d AV |
135 | u32 intervals[INTERVALS]; |
136 | int interval_ptr; | |
4f86d3a8 LB |
137 | }; |
138 | ||
69d25870 AV |
139 | |
140 | #define LOAD_INT(x) ((x) >> FSHIFT) | |
141 | #define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100) | |
142 | ||
143 | static int get_loadavg(void) | |
144 | { | |
145 | unsigned long this = this_cpu_load(); | |
146 | ||
147 | ||
148 | return LOAD_INT(this) * 10 + LOAD_FRAC(this) / 10; | |
149 | } | |
150 | ||
151 | static inline int which_bucket(unsigned int duration) | |
152 | { | |
153 | int bucket = 0; | |
154 | ||
155 | /* | |
156 | * We keep two groups of stats; one with no | |
157 | * IO pending, one without. | |
158 | * This allows us to calculate | |
159 | * E(duration)|iowait | |
160 | */ | |
8c215bd3 | 161 | if (nr_iowait_cpu(smp_processor_id())) |
69d25870 AV |
162 | bucket = BUCKETS/2; |
163 | ||
164 | if (duration < 10) | |
165 | return bucket; | |
166 | if (duration < 100) | |
167 | return bucket + 1; | |
168 | if (duration < 1000) | |
169 | return bucket + 2; | |
170 | if (duration < 10000) | |
171 | return bucket + 3; | |
172 | if (duration < 100000) | |
173 | return bucket + 4; | |
174 | return bucket + 5; | |
175 | } | |
176 | ||
177 | /* | |
178 | * Return a multiplier for the exit latency that is intended | |
179 | * to take performance requirements into account. | |
180 | * The more performance critical we estimate the system | |
181 | * to be, the higher this multiplier, and thus the higher | |
182 | * the barrier to go to an expensive C state. | |
183 | */ | |
184 | static inline int performance_multiplier(void) | |
185 | { | |
186 | int mult = 1; | |
187 | ||
188 | /* for higher loadavg, we are more reluctant */ | |
189 | ||
190 | mult += 2 * get_loadavg(); | |
191 | ||
192 | /* for IO wait tasks (per cpu!) we add 5x each */ | |
8c215bd3 | 193 | mult += 10 * nr_iowait_cpu(smp_processor_id()); |
69d25870 AV |
194 | |
195 | return mult; | |
196 | } | |
197 | ||
4f86d3a8 LB |
198 | static DEFINE_PER_CPU(struct menu_device, menu_devices); |
199 | ||
46bcfad7 | 200 | static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev); |
672917dc | 201 | |
5787536e SH |
202 | /* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */ |
203 | static u64 div_round64(u64 dividend, u32 divisor) | |
204 | { | |
205 | return div_u64(dividend + (divisor / 2), divisor); | |
206 | } | |
207 | ||
69a37bea YS |
208 | /* Cancel the hrtimer if it is not triggered yet */ |
209 | void menu_hrtimer_cancel(void) | |
210 | { | |
211 | int cpu = smp_processor_id(); | |
212 | struct hrtimer *hrtmr = &per_cpu(menu_hrtimer, cpu); | |
213 | ||
214 | /* The timer is still not time out*/ | |
215 | if (per_cpu(hrtimer_status, cpu)) { | |
216 | hrtimer_cancel(hrtmr); | |
217 | per_cpu(hrtimer_status, cpu) = MENU_HRTIMER_STOP; | |
218 | } | |
219 | } | |
220 | EXPORT_SYMBOL_GPL(menu_hrtimer_cancel); | |
221 | ||
222 | /* Call back for hrtimer is triggered */ | |
223 | static enum hrtimer_restart menu_hrtimer_notify(struct hrtimer *hrtimer) | |
224 | { | |
225 | int cpu = smp_processor_id(); | |
e11538d1 YS |
226 | struct menu_device *data = &per_cpu(menu_devices, cpu); |
227 | ||
228 | /* In general case, the expected residency is much larger than | |
229 | * deepest C-state target residency, but prediction logic still | |
230 | * predicts a small predicted residency, so the prediction | |
231 | * history is totally broken if the timer is triggered. | |
232 | * So reset the correction factor. | |
233 | */ | |
234 | if (per_cpu(hrtimer_status, cpu) == MENU_HRTIMER_GENERAL) | |
235 | data->correction_factor[data->bucket] = RESOLUTION * DECAY; | |
69a37bea YS |
236 | |
237 | per_cpu(hrtimer_status, cpu) = MENU_HRTIMER_STOP; | |
238 | ||
239 | return HRTIMER_NORESTART; | |
240 | } | |
241 | ||
1f85f87d AV |
242 | /* |
243 | * Try detecting repeating patterns by keeping track of the last 8 | |
244 | * intervals, and checking if the standard deviation of that set | |
245 | * of points is below a threshold. If it is... then use the | |
246 | * average of these 8 points as the estimated value. | |
247 | */ | |
c96ca4fb | 248 | static u32 get_typical_interval(struct menu_device *data) |
1f85f87d | 249 | { |
c96ca4fb YS |
250 | int i = 0, divisor = 0; |
251 | uint64_t max = 0, avg = 0, stddev = 0; | |
252 | int64_t thresh = LLONG_MAX; /* Discard outliers above this value. */ | |
253 | unsigned int ret = 0; | |
1f85f87d | 254 | |
c96ca4fb | 255 | again: |
1f85f87d | 256 | |
c96ca4fb YS |
257 | /* first calculate average and standard deviation of the past */ |
258 | max = avg = divisor = stddev = 0; | |
259 | for (i = 0; i < INTERVALS; i++) { | |
260 | int64_t value = data->intervals[i]; | |
261 | if (value <= thresh) { | |
262 | avg += value; | |
263 | divisor++; | |
264 | if (value > max) | |
265 | max = value; | |
266 | } | |
267 | } | |
268 | do_div(avg, divisor); | |
269 | ||
270 | for (i = 0; i < INTERVALS; i++) { | |
271 | int64_t value = data->intervals[i]; | |
272 | if (value <= thresh) { | |
273 | int64_t diff = value - avg; | |
274 | stddev += diff * diff; | |
275 | } | |
276 | } | |
277 | do_div(stddev, divisor); | |
278 | stddev = int_sqrt(stddev); | |
1f85f87d | 279 | /* |
c96ca4fb YS |
280 | * If we have outliers to the upside in our distribution, discard |
281 | * those by setting the threshold to exclude these outliers, then | |
282 | * calculate the average and standard deviation again. Once we get | |
283 | * down to the bottom 3/4 of our samples, stop excluding samples. | |
284 | * | |
285 | * This can deal with workloads that have long pauses interspersed | |
286 | * with sporadic activity with a bunch of short pauses. | |
287 | * | |
288 | * The typical interval is obtained when standard deviation is small | |
289 | * or standard deviation is small compared to the average interval. | |
1f85f87d | 290 | */ |
c96ca4fb YS |
291 | if (((avg > stddev * 6) && (divisor * 4 >= INTERVALS * 3)) |
292 | || stddev <= 20) { | |
1f85f87d | 293 | data->predicted_us = avg; |
69a37bea | 294 | ret = 1; |
c96ca4fb YS |
295 | return ret; |
296 | ||
297 | } else if ((divisor * 4) > INTERVALS * 3) { | |
298 | /* Exclude the max interval */ | |
299 | thresh = max - 1; | |
300 | goto again; | |
69a37bea YS |
301 | } |
302 | ||
303 | return ret; | |
1f85f87d AV |
304 | } |
305 | ||
4f86d3a8 LB |
306 | /** |
307 | * menu_select - selects the next idle state to enter | |
46bcfad7 | 308 | * @drv: cpuidle driver containing state data |
4f86d3a8 LB |
309 | * @dev: the CPU |
310 | */ | |
46bcfad7 | 311 | static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) |
4f86d3a8 LB |
312 | { |
313 | struct menu_device *data = &__get_cpu_var(menu_devices); | |
ed77134b | 314 | int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); |
4f86d3a8 | 315 | int i; |
69d25870 | 316 | int multiplier; |
7467571f | 317 | struct timespec t; |
69a37bea YS |
318 | int repeat = 0, low_predicted = 0; |
319 | int cpu = smp_processor_id(); | |
320 | struct hrtimer *hrtmr = &per_cpu(menu_hrtimer, cpu); | |
69d25870 | 321 | |
672917dc | 322 | if (data->needs_update) { |
46bcfad7 | 323 | menu_update(drv, dev); |
672917dc CZ |
324 | data->needs_update = 0; |
325 | } | |
326 | ||
1c6fe036 AV |
327 | data->last_state_idx = 0; |
328 | data->exit_us = 0; | |
329 | ||
a2bd9202 | 330 | /* Special case when user has set very strict latency requirement */ |
69d25870 | 331 | if (unlikely(latency_req == 0)) |
a2bd9202 | 332 | return 0; |
a2bd9202 | 333 | |
69d25870 | 334 | /* determine the expected residency time, round up */ |
7467571f | 335 | t = ktime_to_timespec(tick_nohz_get_sleep_length()); |
4f86d3a8 | 336 | data->expected_us = |
7467571f | 337 | t.tv_sec * USEC_PER_SEC + t.tv_nsec / NSEC_PER_USEC; |
69d25870 AV |
338 | |
339 | ||
340 | data->bucket = which_bucket(data->expected_us); | |
341 | ||
342 | multiplier = performance_multiplier(); | |
343 | ||
344 | /* | |
345 | * if the correction factor is 0 (eg first time init or cpu hotplug | |
346 | * etc), we actually want to start out with a unity factor. | |
347 | */ | |
348 | if (data->correction_factor[data->bucket] == 0) | |
349 | data->correction_factor[data->bucket] = RESOLUTION * DECAY; | |
350 | ||
351 | /* Make sure to round up for half microseconds */ | |
5787536e SH |
352 | data->predicted_us = div_round64(data->expected_us * data->correction_factor[data->bucket], |
353 | RESOLUTION * DECAY); | |
69d25870 | 354 | |
c96ca4fb | 355 | repeat = get_typical_interval(data); |
1f85f87d | 356 | |
69d25870 AV |
357 | /* |
358 | * We want to default to C1 (hlt), not to busy polling | |
359 | * unless the timer is happening really really soon. | |
360 | */ | |
3a53396b | 361 | if (data->expected_us > 5 && |
cbc9ef02 | 362 | !drv->states[CPUIDLE_DRIVER_STATE_START].disabled && |
dc7fd275 | 363 | dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable == 0) |
69d25870 | 364 | data->last_state_idx = CPUIDLE_DRIVER_STATE_START; |
4f86d3a8 | 365 | |
71abbbf8 AL |
366 | /* |
367 | * Find the idle state with the lowest power while satisfying | |
368 | * our constraints. | |
369 | */ | |
46bcfad7 DD |
370 | for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) { |
371 | struct cpuidle_state *s = &drv->states[i]; | |
dc7fd275 | 372 | struct cpuidle_state_usage *su = &dev->states_usage[i]; |
4f86d3a8 | 373 | |
cbc9ef02 | 374 | if (s->disabled || su->disable) |
3a53396b | 375 | continue; |
69a37bea YS |
376 | if (s->target_residency > data->predicted_us) { |
377 | low_predicted = 1; | |
71abbbf8 | 378 | continue; |
69a37bea | 379 | } |
a2bd9202 | 380 | if (s->exit_latency > latency_req) |
71abbbf8 | 381 | continue; |
69d25870 | 382 | if (s->exit_latency * multiplier > data->predicted_us) |
71abbbf8 AL |
383 | continue; |
384 | ||
8aef33a7 DL |
385 | data->last_state_idx = i; |
386 | data->exit_us = s->exit_latency; | |
4f86d3a8 LB |
387 | } |
388 | ||
69a37bea YS |
389 | /* not deepest C-state chosen for low predicted residency */ |
390 | if (low_predicted) { | |
391 | unsigned int timer_us = 0; | |
e11538d1 | 392 | unsigned int perfect_us = 0; |
69a37bea YS |
393 | |
394 | /* | |
395 | * Set a timer to detect whether this sleep is much | |
396 | * longer than repeat mode predicted. If the timer | |
397 | * triggers, the code will evaluate whether to put | |
398 | * the CPU into a deeper C-state. | |
399 | * The timer is cancelled on CPU wakeup. | |
400 | */ | |
401 | timer_us = 2 * (data->predicted_us + MAX_DEVIATION); | |
402 | ||
e11538d1 YS |
403 | perfect_us = perfect_cstate_ms * 1000; |
404 | ||
69a37bea | 405 | if (repeat && (4 * timer_us < data->expected_us)) { |
a093b93e LZ |
406 | RCU_NONIDLE(hrtimer_start(hrtmr, |
407 | ns_to_ktime(1000 * timer_us), | |
408 | HRTIMER_MODE_REL_PINNED)); | |
69a37bea YS |
409 | /* In repeat case, menu hrtimer is started */ |
410 | per_cpu(hrtimer_status, cpu) = MENU_HRTIMER_REPEAT; | |
e11538d1 YS |
411 | } else if (perfect_us < data->expected_us) { |
412 | /* | |
413 | * The next timer is long. This could be because | |
414 | * we did not make a useful prediction. | |
415 | * In that case, it makes sense to re-enter | |
416 | * into a deeper C-state after some time. | |
417 | */ | |
a093b93e LZ |
418 | RCU_NONIDLE(hrtimer_start(hrtmr, |
419 | ns_to_ktime(1000 * timer_us), | |
420 | HRTIMER_MODE_REL_PINNED)); | |
e11538d1 YS |
421 | /* In general case, menu hrtimer is started */ |
422 | per_cpu(hrtimer_status, cpu) = MENU_HRTIMER_GENERAL; | |
69a37bea | 423 | } |
e11538d1 | 424 | |
69a37bea YS |
425 | } |
426 | ||
69d25870 | 427 | return data->last_state_idx; |
4f86d3a8 LB |
428 | } |
429 | ||
430 | /** | |
672917dc | 431 | * menu_reflect - records that data structures need update |
4f86d3a8 | 432 | * @dev: the CPU |
e978aa7d | 433 | * @index: the index of actual entered state |
4f86d3a8 LB |
434 | * |
435 | * NOTE: it's important to be fast here because this operation will add to | |
436 | * the overall exit latency. | |
437 | */ | |
e978aa7d | 438 | static void menu_reflect(struct cpuidle_device *dev, int index) |
672917dc CZ |
439 | { |
440 | struct menu_device *data = &__get_cpu_var(menu_devices); | |
e978aa7d DD |
441 | data->last_state_idx = index; |
442 | if (index >= 0) | |
443 | data->needs_update = 1; | |
672917dc CZ |
444 | } |
445 | ||
446 | /** | |
447 | * menu_update - attempts to guess what happened after entry | |
46bcfad7 | 448 | * @drv: cpuidle driver containing state data |
672917dc CZ |
449 | * @dev: the CPU |
450 | */ | |
46bcfad7 | 451 | static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) |
4f86d3a8 LB |
452 | { |
453 | struct menu_device *data = &__get_cpu_var(menu_devices); | |
454 | int last_idx = data->last_state_idx; | |
320eee77 | 455 | unsigned int last_idle_us = cpuidle_get_last_residency(dev); |
46bcfad7 | 456 | struct cpuidle_state *target = &drv->states[last_idx]; |
320eee77 | 457 | unsigned int measured_us; |
69d25870 | 458 | u64 new_factor; |
4f86d3a8 LB |
459 | |
460 | /* | |
461 | * Ugh, this idle state doesn't support residency measurements, so we | |
462 | * are basically lost in the dark. As a compromise, assume we slept | |
69d25870 | 463 | * for the whole expected time. |
4f86d3a8 | 464 | */ |
320eee77 | 465 | if (unlikely(!(target->flags & CPUIDLE_FLAG_TIME_VALID))) |
69d25870 AV |
466 | last_idle_us = data->expected_us; |
467 | ||
468 | ||
469 | measured_us = last_idle_us; | |
4f86d3a8 | 470 | |
320eee77 | 471 | /* |
69d25870 AV |
472 | * We correct for the exit latency; we are assuming here that the |
473 | * exit latency happens after the event that we're interested in. | |
320eee77 | 474 | */ |
69d25870 AV |
475 | if (measured_us > data->exit_us) |
476 | measured_us -= data->exit_us; | |
477 | ||
478 | ||
479 | /* update our correction ratio */ | |
480 | ||
481 | new_factor = data->correction_factor[data->bucket] | |
482 | * (DECAY - 1) / DECAY; | |
483 | ||
1c6fe036 | 484 | if (data->expected_us > 0 && measured_us < MAX_INTERESTING) |
69d25870 | 485 | new_factor += RESOLUTION * measured_us / data->expected_us; |
320eee77 | 486 | else |
69d25870 AV |
487 | /* |
488 | * we were idle so long that we count it as a perfect | |
489 | * prediction | |
490 | */ | |
491 | new_factor += RESOLUTION; | |
320eee77 | 492 | |
69d25870 AV |
493 | /* |
494 | * We don't want 0 as factor; we always want at least | |
495 | * a tiny bit of estimated time. | |
496 | */ | |
497 | if (new_factor == 0) | |
498 | new_factor = 1; | |
320eee77 | 499 | |
69d25870 | 500 | data->correction_factor[data->bucket] = new_factor; |
1f85f87d AV |
501 | |
502 | /* update the repeating-pattern data */ | |
503 | data->intervals[data->interval_ptr++] = last_idle_us; | |
504 | if (data->interval_ptr >= INTERVALS) | |
505 | data->interval_ptr = 0; | |
4f86d3a8 LB |
506 | } |
507 | ||
508 | /** | |
509 | * menu_enable_device - scans a CPU's states and does setup | |
46bcfad7 | 510 | * @drv: cpuidle driver |
4f86d3a8 LB |
511 | * @dev: the CPU |
512 | */ | |
46bcfad7 DD |
513 | static int menu_enable_device(struct cpuidle_driver *drv, |
514 | struct cpuidle_device *dev) | |
4f86d3a8 LB |
515 | { |
516 | struct menu_device *data = &per_cpu(menu_devices, dev->cpu); | |
69a37bea YS |
517 | struct hrtimer *t = &per_cpu(menu_hrtimer, dev->cpu); |
518 | hrtimer_init(t, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
519 | t->function = menu_hrtimer_notify; | |
4f86d3a8 LB |
520 | |
521 | memset(data, 0, sizeof(struct menu_device)); | |
522 | ||
523 | return 0; | |
524 | } | |
525 | ||
526 | static struct cpuidle_governor menu_governor = { | |
527 | .name = "menu", | |
528 | .rating = 20, | |
529 | .enable = menu_enable_device, | |
530 | .select = menu_select, | |
531 | .reflect = menu_reflect, | |
532 | .owner = THIS_MODULE, | |
533 | }; | |
534 | ||
535 | /** | |
536 | * init_menu - initializes the governor | |
537 | */ | |
538 | static int __init init_menu(void) | |
539 | { | |
540 | return cpuidle_register_governor(&menu_governor); | |
541 | } | |
542 | ||
543 | /** | |
544 | * exit_menu - exits the governor | |
545 | */ | |
546 | static void __exit exit_menu(void) | |
547 | { | |
548 | cpuidle_unregister_governor(&menu_governor); | |
549 | } | |
550 | ||
551 | MODULE_LICENSE("GPL"); | |
552 | module_init(init_menu); | |
553 | module_exit(exit_menu); |