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/rcupdate.h>
9 #include <linux/sched/cpufreq.h>
10 #include <linux/sched/topology.h>
11 #include <linux/types.h>
14 * em_perf_state - Performance state of a performance domain
15 * @frequency: The frequency in KHz, for consistency with CPUFreq
16 * @power: The power consumed at this level (by 1 CPU or by a registered
17 * device). It can be a total power: static and dynamic.
18 * @cost: The cost coefficient associated with this level, used during
19 * energy calculation. Equal to: power * max_frequency / frequency
21 struct em_perf_state {
22 unsigned long frequency;
28 * em_perf_domain - Performance domain
29 * @table: List of performance states, in ascending order
30 * @nr_perf_states: Number of performance states
31 * @milliwatts: Flag indicating the power values are in milli-Watts
32 * or some other scale.
33 * @cpus: Cpumask covering the CPUs of the domain. It's here
34 * for performance reasons to avoid potential cache
35 * misses during energy calculations in the scheduler
36 * and simplifies allocating/freeing that memory region.
38 * In case of CPU device, a "performance domain" represents a group of CPUs
39 * whose performance is scaled together. All CPUs of a performance domain
40 * must have the same micro-architecture. Performance domains often have
41 * a 1-to-1 mapping with CPUFreq policies. In case of other devices the @cpus
44 struct em_perf_domain {
45 struct em_perf_state *table;
51 #define em_span_cpus(em) (to_cpumask((em)->cpus))
53 #ifdef CONFIG_ENERGY_MODEL
54 #define EM_MAX_POWER 0xFFFF
56 struct em_data_callback {
58 * active_power() - Provide power at the next performance state of
60 * @power : Active power at the performance state
62 * @freq : Frequency at the performance state in kHz
64 * @dev : Device for which we do this operation (can be a CPU)
66 * active_power() must find the lowest performance state of 'dev' above
67 * 'freq' and update 'power' and 'freq' to the matching active power
70 * In case of CPUs, the power is the one of a single CPU in the domain,
71 * expressed in milli-Watts or an abstract scale. It is expected to
72 * fit in the [0, EM_MAX_POWER] range.
74 * Return 0 on success.
76 int (*active_power)(unsigned long *power, unsigned long *freq,
79 #define EM_DATA_CB(_active_power_cb) { .active_power = &_active_power_cb }
81 struct em_perf_domain *em_cpu_get(int cpu);
82 struct em_perf_domain *em_pd_get(struct device *dev);
83 int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
84 struct em_data_callback *cb, cpumask_t *span,
86 void em_dev_unregister_perf_domain(struct device *dev);
89 * em_cpu_energy() - Estimates the energy consumed by the CPUs of a
91 * @pd : performance domain for which energy has to be estimated
92 * @max_util : highest utilization among CPUs of the domain
93 * @sum_util : sum of the utilization of all CPUs in the domain
94 * @allowed_cpu_cap : maximum allowed CPU capacity for the @pd, which
95 might reflect reduced frequency (due to thermal)
97 * This function must be used only for CPU devices. There is no validation,
98 * i.e. if the EM is a CPU type and has cpumask allocated. It is called from
99 * the scheduler code quite frequently and that is why there is not checks.
101 * Return: the sum of the energy consumed by the CPUs of the domain assuming
102 * a capacity state satisfying the max utilization of the domain.
104 static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
105 unsigned long max_util, unsigned long sum_util,
106 unsigned long allowed_cpu_cap)
108 unsigned long freq, scale_cpu;
109 struct em_perf_state *ps;
116 * In order to predict the performance state, map the utilization of
117 * the most utilized CPU of the performance domain to a requested
118 * frequency, like schedutil. Take also into account that the real
119 * frequency might be set lower (due to thermal capping). Thus, clamp
120 * max utilization to the allowed CPU capacity before calculating
121 * effective frequency.
123 cpu = cpumask_first(to_cpumask(pd->cpus));
124 scale_cpu = arch_scale_cpu_capacity(cpu);
125 ps = &pd->table[pd->nr_perf_states - 1];
127 max_util = map_util_perf(max_util);
128 max_util = min(max_util, allowed_cpu_cap);
129 freq = map_util_freq(max_util, ps->frequency, scale_cpu);
132 * Find the lowest performance state of the Energy Model above the
133 * requested frequency.
135 for (i = 0; i < pd->nr_perf_states; i++) {
137 if (ps->frequency >= freq)
142 * The capacity of a CPU in the domain at the performance state (ps)
143 * can be computed as:
145 * ps->freq * scale_cpu
146 * ps->cap = -------------------- (1)
149 * So, ignoring the costs of idle states (which are not available in
150 * the EM), the energy consumed by this CPU at that performance state
153 * ps->power * cpu_util
154 * cpu_nrg = -------------------- (2)
157 * since 'cpu_util / ps->cap' represents its percentage of busy time.
159 * NOTE: Although the result of this computation actually is in
160 * units of power, it can be manipulated as an energy value
161 * over a scheduling period, since it is assumed to be
162 * constant during that interval.
164 * By injecting (1) in (2), 'cpu_nrg' can be re-expressed as a product
167 * ps->power * cpu_max_freq cpu_util
168 * cpu_nrg = ------------------------ * --------- (3)
171 * The first term is static, and is stored in the em_perf_state struct
174 * Since all CPUs of the domain have the same micro-architecture, they
175 * share the same 'ps->cost', and the same CPU capacity. Hence, the
176 * total energy of the domain (which is the simple sum of the energy of
177 * all of its CPUs) can be factorized as:
179 * ps->cost * \Sum cpu_util
180 * pd_nrg = ------------------------ (4)
183 return ps->cost * sum_util / scale_cpu;
187 * em_pd_nr_perf_states() - Get the number of performance states of a perf.
189 * @pd : performance domain for which this must be done
191 * Return: the number of performance states in the performance domain table
193 static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
195 return pd->nr_perf_states;
199 struct em_data_callback {};
200 #define EM_DATA_CB(_active_power_cb) { }
203 int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
204 struct em_data_callback *cb, cpumask_t *span,
209 static inline void em_dev_unregister_perf_domain(struct device *dev)
212 static inline struct em_perf_domain *em_cpu_get(int cpu)
216 static inline struct em_perf_domain *em_pd_get(struct device *dev)
220 static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
221 unsigned long max_util, unsigned long sum_util,
222 unsigned long allowed_cpu_cap)
226 static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)