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> 12 13 /** 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 20 */ 21 struct em_perf_state { 22 unsigned long frequency; 23 unsigned long power; 24 unsigned long cost; 25 }; 26 27 /** 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. 37 * 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 42 * field is unused. 43 */ 44 struct em_perf_domain { 45 struct em_perf_state *table; 46 int nr_perf_states; 47 int milliwatts; 48 unsigned long cpus[]; 49 }; 50 51 #define em_span_cpus(em) (to_cpumask((em)->cpus)) 52 53 #ifdef CONFIG_ENERGY_MODEL 54 #define EM_MAX_POWER 0xFFFF 55 56 struct em_data_callback { 57 /** 58 * active_power() - Provide power at the next performance state of 59 * a device 60 * @power : Active power at the performance state 61 * (modified) 62 * @freq : Frequency at the performance state in kHz 63 * (modified) 64 * @dev : Device for which we do this operation (can be a CPU) 65 * 66 * active_power() must find the lowest performance state of 'dev' above 67 * 'freq' and update 'power' and 'freq' to the matching active power 68 * and frequency. 69 * 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. 73 * 74 * Return 0 on success. 75 */ 76 int (*active_power)(unsigned long *power, unsigned long *freq, 77 struct device *dev); 78 }; 79 #define EM_DATA_CB(_active_power_cb) { .active_power = &_active_power_cb } 80 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, 85 bool milliwatts); 86 void em_dev_unregister_perf_domain(struct device *dev); 87 88 /** 89 * em_cpu_energy() - Estimates the energy consumed by the CPUs of a 90 performance domain 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) 96 * 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. 100 * 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. 103 */ 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) 107 { 108 unsigned long freq, scale_cpu; 109 struct em_perf_state *ps; 110 int i, cpu; 111 112 if (!sum_util) 113 return 0; 114 115 /* 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. 122 */ 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]; 126 127 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); 130 131 /* 132 * Find the lowest performance state of the Energy Model above the 133 * requested frequency. 134 */ 135 for (i = 0; i < pd->nr_perf_states; i++) { 136 ps = &pd->table[i]; 137 if (ps->frequency >= freq) 138 break; 139 } 140 141 /* 142 * The capacity of a CPU in the domain at the performance state (ps) 143 * can be computed as: 144 * 145 * ps->freq * scale_cpu 146 * ps->cap = -------------------- (1) 147 * cpu_max_freq 148 * 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 151 * is estimated as: 152 * 153 * ps->power * cpu_util 154 * cpu_nrg = -------------------- (2) 155 * ps->cap 156 * 157 * since 'cpu_util / ps->cap' represents its percentage of busy time. 158 * 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. 163 * 164 * By injecting (1) in (2), 'cpu_nrg' can be re-expressed as a product 165 * of two terms: 166 * 167 * ps->power * cpu_max_freq cpu_util 168 * cpu_nrg = ------------------------ * --------- (3) 169 * ps->freq scale_cpu 170 * 171 * The first term is static, and is stored in the em_perf_state struct 172 * as 'ps->cost'. 173 * 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: 178 * 179 * ps->cost * \Sum cpu_util 180 * pd_nrg = ------------------------ (4) 181 * scale_cpu 182 */ 183 return ps->cost * sum_util / scale_cpu; 184 } 185 186 /** 187 * em_pd_nr_perf_states() - Get the number of performance states of a perf. 188 * domain 189 * @pd : performance domain for which this must be done 190 * 191 * Return: the number of performance states in the performance domain table 192 */ 193 static inline int em_pd_nr_perf_states(struct em_perf_domain *pd) 194 { 195 return pd->nr_perf_states; 196 } 197 198 #else 199 struct em_data_callback {}; 200 #define EM_DATA_CB(_active_power_cb) { } 201 202 static inline 203 int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, 204 struct em_data_callback *cb, cpumask_t *span, 205 bool milliwatts) 206 { 207 return -EINVAL; 208 } 209 static inline void em_dev_unregister_perf_domain(struct device *dev) 210 { 211 } 212 static inline struct em_perf_domain *em_cpu_get(int cpu) 213 { 214 return NULL; 215 } 216 static inline struct em_perf_domain *em_pd_get(struct device *dev) 217 { 218 return NULL; 219 } 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) 223 { 224 return 0; 225 } 226 static inline int em_pd_nr_perf_states(struct em_perf_domain *pd) 227 { 228 return 0; 229 } 230 #endif 231 232 #endif 233