include/linux/energy_model.h

1 /* SPDX-License-Identifier: GPL-2.0 */
14  * em_perf_state - Performance state of a performance domain
16  * @power:	The power consumed at this level, in milli-watts (by 1 CPU or
29  * em_perf_domain - Performance domain
32  * @cpus:		Cpumask covering the CPUs of the domain. It's here
37  * In case of CPU device, a "performance domain" represents a group of CPUs
38  * whose performance is scaled together. All CPUs of a performance domain
39  * must have the same micro-architecture. Performance domains often have
40  * a 1-to-1 mapping with CPUFreq policies. In case of other devices the @cpus
49 #define em_span_cpus(em) (to_cpumask((em)->cpus))
56 	 * active_power() - Provide power at the next performance state of
58 	 * @power	: Active power at the performance state in mW
60 	 * @freq	: Frequency at the performance state in kHz
64 	 * active_power() must find the lowest performance state of 'dev' above
68 	 * In case of CPUs, the power is the one of a single CPU in the domain,
69 	 * expressed in milli-watts. It is expected to fit in the
86  * em_cpu_energy() - Estimates the energy consumed by the CPUs of a
87 		performance domain
88  * @pd		: performance domain for which energy has to be estimated
89  * @max_util	: highest utilization among CPUs of the domain
90  * @sum_util	: sum of the utilization of all CPUs in the domain
96  * Return: the sum of the energy consumed by the CPUs of the domain assuming
97  * a capacity state satisfying the max utilization of the domain.
107 	 * In order to predict the performance state, map the utilization of  in em_cpu_energy()
108 	 * the most utilized CPU of the performance domain to a requested  in em_cpu_energy()
111 	cpu = cpumask_first(to_cpumask(pd->cpus));  in em_cpu_energy()
113 	ps = &pd->table[pd->nr_perf_states - 1];  in em_cpu_energy()
114 	freq = map_util_freq(max_util, ps->frequency, scale_cpu);  in em_cpu_energy()
117 	 * Find the lowest performance state of the Energy Model above the  in em_cpu_energy()
120 	for (i = 0; i < pd->nr_perf_states; i++) {  in em_cpu_energy()
121 		ps = &pd->table[i];  in em_cpu_energy()
122 		if (ps->frequency >= freq)  in em_cpu_energy()
127 	 * The capacity of a CPU in the domain at the performance state (ps)  in em_cpu_energy()
130 	 *             ps->freq * scale_cpu  in em_cpu_energy()
131 	 *   ps->cap = --------------------                          (1)  in em_cpu_energy()
134 	 * So, ignoring the costs of idle states (which are not available in  in em_cpu_energy()
135 	 * the EM), the energy consumed by this CPU at that performance state  in em_cpu_energy()
138 	 *             ps->power * cpu_util  in em_cpu_energy()
139 	 *   cpu_nrg = --------------------                          (2)  in em_cpu_energy()
140 	 *                   ps->cap  in em_cpu_energy()
142 	 * since 'cpu_util / ps->cap' represents its percentage of busy time.  in em_cpu_energy()
149 	 * By injecting (1) in (2), 'cpu_nrg' can be re-expressed as a product  in em_cpu_energy()
152 	 *             ps->power * cpu_max_freq   cpu_util  in em_cpu_energy()
153 	 *   cpu_nrg = ------------------------ * ---------          (3)  in em_cpu_energy()
154 	 *                    ps->freq            scale_cpu  in em_cpu_energy()
157 	 * as 'ps->cost'.  in em_cpu_energy()
159 	 * Since all CPUs of the domain have the same micro-architecture, they  in em_cpu_energy()
160 	 * share the same 'ps->cost', and the same CPU capacity. Hence, the  in em_cpu_energy()
161 	 * total energy of the domain (which is the simple sum of the energy of  in em_cpu_energy()
164 	 *            ps->cost * \Sum cpu_util  in em_cpu_energy()
165 	 *   pd_nrg = ------------------------                       (4)  in em_cpu_energy()
168 	return ps->cost * sum_util / scale_cpu;  in em_cpu_energy()
172  * em_pd_nr_perf_states() - Get the number of performance states of a perf.
173  *				domain
174  * @pd		: performance domain for which this must be done
176  * Return: the number of performance states in the performance domain table
180 	return pd->nr_perf_states;  in em_pd_nr_perf_states()
191 	return -EINVAL;  in em_dev_register_perf_domain()