1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_ENERGY_MODEL_H
3#define _LINUX_ENERGY_MODEL_H
4#include <linux/cpumask.h>
5#include <linux/device.h>
6#include <linux/jump_label.h>
7#include <linux/kobject.h>
8#include <linux/kref.h>
9#include <linux/rcupdate.h>
10#include <linux/sched/cpufreq.h>
11#include <linux/sched/topology.h>
12#include <linux/types.h>
13
14/**
15 * struct em_perf_state - Performance state of a performance domain
16 * @performance: CPU performance (capacity) at a given frequency
17 * @frequency: The frequency in KHz, for consistency with CPUFreq
18 * @power: The power consumed at this level (by 1 CPU or by a registered
19 * device). It can be a total power: static and dynamic.
20 * @cost: The cost coefficient associated with this level, used during
21 * energy calculation. Equal to: power * max_frequency / frequency
22 * @flags: see "em_perf_state flags" description below.
23 */
24struct em_perf_state {
25 unsigned long performance;
26 unsigned long frequency;
27 unsigned long power;
28 unsigned long cost;
29 unsigned long flags;
30};
31
32/*
33 * em_perf_state flags:
34 *
35 * EM_PERF_STATE_INEFFICIENT: The performance state is inefficient. There is
36 * in this em_perf_domain, another performance state with a higher frequency
37 * but a lower or equal power cost. Such inefficient states are ignored when
38 * using em_pd_get_efficient_*() functions.
39 */
40#define EM_PERF_STATE_INEFFICIENT BIT(0)
41
42/**
43 * struct em_perf_table - Performance states table
44 * @rcu: RCU used for safe access and destruction
45 * @kref: Reference counter to track the users
46 * @state: List of performance states, in ascending order
47 */
48struct em_perf_table {
49 struct rcu_head rcu;
50 struct kref kref;
51 struct em_perf_state state[];
52};
53
54/**
55 * struct em_perf_domain - Performance domain
56 * @em_table: Pointer to the runtime modifiable em_perf_table
57 * @nr_perf_states: Number of performance states
58 * @min_perf_state: Minimum allowed Performance State index
59 * @max_perf_state: Maximum allowed Performance State index
60 * @flags: See "em_perf_domain flags"
61 * @cpus: Cpumask covering the CPUs of the domain. It's here
62 * for performance reasons to avoid potential cache
63 * misses during energy calculations in the scheduler
64 * and simplifies allocating/freeing that memory region.
65 *
66 * In case of CPU device, a "performance domain" represents a group of CPUs
67 * whose performance is scaled together. All CPUs of a performance domain
68 * must have the same micro-architecture. Performance domains often have
69 * a 1-to-1 mapping with CPUFreq policies. In case of other devices the @cpus
70 * field is unused.
71 */
72struct em_perf_domain {
73 struct em_perf_table __rcu *em_table;
74 int nr_perf_states;
75 int min_perf_state;
76 int max_perf_state;
77 unsigned long flags;
78 unsigned long cpus[];
79};
80
81/*
82 * em_perf_domain flags:
83 *
84 * EM_PERF_DOMAIN_MICROWATTS: The power values are in micro-Watts or some
85 * other scale.
86 *
87 * EM_PERF_DOMAIN_SKIP_INEFFICIENCIES: Skip inefficient states when estimating
88 * energy consumption.
89 *
90 * EM_PERF_DOMAIN_ARTIFICIAL: The power values are artificial and might be
91 * created by platform missing real power information
92 */
93#define EM_PERF_DOMAIN_MICROWATTS BIT(0)
94#define EM_PERF_DOMAIN_SKIP_INEFFICIENCIES BIT(1)
95#define EM_PERF_DOMAIN_ARTIFICIAL BIT(2)
96
97#define em_span_cpus(em) (to_cpumask((em)->cpus))
98#define em_is_artificial(em) ((em)->flags & EM_PERF_DOMAIN_ARTIFICIAL)
99
100#ifdef CONFIG_ENERGY_MODEL
101/*
102 * The max power value in micro-Watts. The limit of 64 Watts is set as
103 * a safety net to not overflow multiplications on 32bit platforms. The
104 * 32bit value limit for total Perf Domain power implies a limit of
105 * maximum CPUs in such domain to 64.
106 */
107#define EM_MAX_POWER (64000000) /* 64 Watts */
108
109/*
110 * To avoid possible energy estimation overflow on 32bit machines add
111 * limits to number of CPUs in the Perf. Domain.
112 * We are safe on 64bit machine, thus some big number.
113 */
114#ifdef CONFIG_64BIT
115#define EM_MAX_NUM_CPUS 4096
116#else
117#define EM_MAX_NUM_CPUS 16
118#endif
119
120struct em_data_callback {
121 /**
122 * active_power() - Provide power at the next performance state of
123 * a device
124 * @dev : Device for which we do this operation (can be a CPU)
125 * @power : Active power at the performance state
126 * (modified)
127 * @freq : Frequency at the performance state in kHz
128 * (modified)
129 *
130 * active_power() must find the lowest performance state of 'dev' above
131 * 'freq' and update 'power' and 'freq' to the matching active power
132 * and frequency.
133 *
134 * In case of CPUs, the power is the one of a single CPU in the domain,
135 * expressed in micro-Watts or an abstract scale. It is expected to
136 * fit in the [0, EM_MAX_POWER] range.
137 *
138 * Return 0 on success.
139 */
140 int (*active_power)(struct device *dev, unsigned long *power,
141 unsigned long *freq);
142
143 /**
144 * get_cost() - Provide the cost at the given performance state of
145 * a device
146 * @dev : Device for which we do this operation (can be a CPU)
147 * @freq : Frequency at the performance state in kHz
148 * @cost : The cost value for the performance state
149 * (modified)
150 *
151 * In case of CPUs, the cost is the one of a single CPU in the domain.
152 * It is expected to fit in the [0, EM_MAX_POWER] range due to internal
153 * usage in EAS calculation.
154 *
155 * Return 0 on success, or appropriate error value in case of failure.
156 */
157 int (*get_cost)(struct device *dev, unsigned long freq,
158 unsigned long *cost);
159};
160#define EM_SET_ACTIVE_POWER_CB(em_cb, cb) ((em_cb).active_power = cb)
161#define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) \
162 { .active_power = _active_power_cb, \
163 .get_cost = _cost_cb }
164#define EM_DATA_CB(_active_power_cb) \
165 EM_ADV_DATA_CB(_active_power_cb, NULL)
166
167struct em_perf_domain *em_cpu_get(int cpu);
168struct em_perf_domain *em_pd_get(struct device *dev);
169int em_dev_update_perf_domain(struct device *dev,
170 struct em_perf_table *new_table);
171int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
172 const struct em_data_callback *cb,
173 const cpumask_t *cpus, bool microwatts);
174void em_dev_unregister_perf_domain(struct device *dev);
175struct em_perf_table *em_table_alloc(struct em_perf_domain *pd);
176void em_table_free(struct em_perf_table *table);
177int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
178 int nr_states);
179int em_dev_update_chip_binning(struct device *dev);
180int em_update_performance_limits(struct em_perf_domain *pd,
181 unsigned long freq_min_khz, unsigned long freq_max_khz);
182void em_adjust_cpu_capacity(unsigned int cpu);
183void em_rebuild_sched_domains(void);
184
185/**
186 * em_pd_get_efficient_state() - Get an efficient performance state from the EM
187 * @table: List of performance states, in ascending order
188 * @pd: performance domain for which this must be done
189 * @max_util: Max utilization to map with the EM
190 *
191 * It is called from the scheduler code quite frequently and as a consequence
192 * doesn't implement any check.
193 *
194 * Return: An efficient performance state id, high enough to meet @max_util
195 * requirement.
196 */
197static inline int
198em_pd_get_efficient_state(struct em_perf_state *table,
199 struct em_perf_domain *pd, unsigned long max_util)
200{
201 unsigned long pd_flags = pd->flags;
202 int min_ps = pd->min_perf_state;
203 int max_ps = pd->max_perf_state;
204 struct em_perf_state *ps;
205 int i;
206
207 for (i = min_ps; i <= max_ps; i++) {
208 ps = &table[i];
209 if (ps->performance >= max_util) {
210 if (pd_flags & EM_PERF_DOMAIN_SKIP_INEFFICIENCIES &&
211 ps->flags & EM_PERF_STATE_INEFFICIENT)
212 continue;
213 return i;
214 }
215 }
216
217 return max_ps;
218}
219
220/**
221 * em_cpu_energy() - Estimates the energy consumed by the CPUs of a
222 * performance domain
223 * @pd : performance domain for which energy has to be estimated
224 * @max_util : highest utilization among CPUs of the domain
225 * @sum_util : sum of the utilization of all CPUs in the domain
226 * @allowed_cpu_cap : maximum allowed CPU capacity for the @pd, which
227 * might reflect reduced frequency (due to thermal)
228 *
229 * This function must be used only for CPU devices. There is no validation,
230 * i.e. if the EM is a CPU type and has cpumask allocated. It is called from
231 * the scheduler code quite frequently and that is why there is not checks.
232 *
233 * Return: the sum of the energy consumed by the CPUs of the domain assuming
234 * a capacity state satisfying the max utilization of the domain.
235 */
236static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
237 unsigned long max_util, unsigned long sum_util,
238 unsigned long allowed_cpu_cap)
239{
240 struct em_perf_table *em_table;
241 struct em_perf_state *ps;
242 int i;
243
244 WARN_ONCE(!rcu_read_lock_held(), "EM: rcu read lock needed\n");
245
246 if (!sum_util)
247 return 0;
248
249 /*
250 * In order to predict the performance state, map the utilization of
251 * the most utilized CPU of the performance domain to a requested
252 * performance, like schedutil. Take also into account that the real
253 * performance might be set lower (due to thermal capping). Thus, clamp
254 * max utilization to the allowed CPU capacity before calculating
255 * effective performance.
256 */
257 max_util = min(max_util, allowed_cpu_cap);
258
259 /*
260 * Find the lowest performance state of the Energy Model above the
261 * requested performance.
262 */
263 em_table = rcu_dereference(pd->em_table);
264 i = em_pd_get_efficient_state(table: em_table->state, pd, max_util);
265 ps = &em_table->state[i];
266
267 /*
268 * The performance (capacity) of a CPU in the domain at the performance
269 * state (ps) can be computed as:
270 *
271 * ps->freq * scale_cpu
272 * ps->performance = -------------------- (1)
273 * cpu_max_freq
274 *
275 * So, ignoring the costs of idle states (which are not available in
276 * the EM), the energy consumed by this CPU at that performance state
277 * is estimated as:
278 *
279 * ps->power * cpu_util
280 * cpu_nrg = -------------------- (2)
281 * ps->performance
282 *
283 * since 'cpu_util / ps->performance' represents its percentage of busy
284 * time.
285 *
286 * NOTE: Although the result of this computation actually is in
287 * units of power, it can be manipulated as an energy value
288 * over a scheduling period, since it is assumed to be
289 * constant during that interval.
290 *
291 * By injecting (1) in (2), 'cpu_nrg' can be re-expressed as a product
292 * of two terms:
293 *
294 * ps->power * cpu_max_freq
295 * cpu_nrg = ------------------------ * cpu_util (3)
296 * ps->freq * scale_cpu
297 *
298 * The first term is static, and is stored in the em_perf_state struct
299 * as 'ps->cost'.
300 *
301 * Since all CPUs of the domain have the same micro-architecture, they
302 * share the same 'ps->cost', and the same CPU capacity. Hence, the
303 * total energy of the domain (which is the simple sum of the energy of
304 * all of its CPUs) can be factorized as:
305 *
306 * pd_nrg = ps->cost * \Sum cpu_util (4)
307 */
308 return ps->cost * sum_util;
309}
310
311/**
312 * em_pd_nr_perf_states() - Get the number of performance states of a perf.
313 * domain
314 * @pd : performance domain for which this must be done
315 *
316 * Return: the number of performance states in the performance domain table
317 */
318static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
319{
320 return pd->nr_perf_states;
321}
322
323/**
324 * em_perf_state_from_pd() - Get the performance states table of perf.
325 * domain
326 * @pd : performance domain for which this must be done
327 *
328 * To use this function the rcu_read_lock() should be hold. After the usage
329 * of the performance states table is finished, the rcu_read_unlock() should
330 * be called.
331 *
332 * Return: the pointer to performance states table of the performance domain
333 */
334static inline
335struct em_perf_state *em_perf_state_from_pd(struct em_perf_domain *pd)
336{
337 return rcu_dereference(pd->em_table)->state;
338}
339
340#else
341struct em_data_callback {};
342#define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) { }
343#define EM_DATA_CB(_active_power_cb) { }
344#define EM_SET_ACTIVE_POWER_CB(em_cb, cb) do { } while (0)
345
346static inline
347int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
348 const struct em_data_callback *cb,
349 const cpumask_t *cpus, bool microwatts)
350{
351 return -EINVAL;
352}
353static inline void em_dev_unregister_perf_domain(struct device *dev)
354{
355}
356static inline struct em_perf_domain *em_cpu_get(int cpu)
357{
358 return NULL;
359}
360static inline struct em_perf_domain *em_pd_get(struct device *dev)
361{
362 return NULL;
363}
364static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
365 unsigned long max_util, unsigned long sum_util,
366 unsigned long allowed_cpu_cap)
367{
368 return 0;
369}
370static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
371{
372 return 0;
373}
374static inline
375struct em_perf_table *em_table_alloc(struct em_perf_domain *pd)
376{
377 return NULL;
378}
379static inline void em_table_free(struct em_perf_table *table) {}
380static inline
381int em_dev_update_perf_domain(struct device *dev,
382 struct em_perf_table *new_table)
383{
384 return -EINVAL;
385}
386static inline
387struct em_perf_state *em_perf_state_from_pd(struct em_perf_domain *pd)
388{
389 return NULL;
390}
391static inline
392int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
393 int nr_states)
394{
395 return -EINVAL;
396}
397static inline int em_dev_update_chip_binning(struct device *dev)
398{
399 return -EINVAL;
400}
401static inline
402int em_update_performance_limits(struct em_perf_domain *pd,
403 unsigned long freq_min_khz, unsigned long freq_max_khz)
404{
405 return -EINVAL;
406}
407static inline void em_adjust_cpu_capacity(unsigned int cpu) {}
408static inline void em_rebuild_sched_domains(void) {}
409#endif
410
411#endif
412

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source code of linux/include/linux/energy_model.h