1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_ENERGY_MODEL_H
#define _LINUX_ENERGY_MODEL_H
#include <linux/cpumask.h>
#include <linux/jump_label.h>
#include <linux/kobject.h>
#include <linux/rcupdate.h>
#include <linux/sched/cpufreq.h>
#include <linux/sched/topology.h>
#include <linux/types.h>
/**
* em_cap_state - Capacity state of a performance domain
* @frequency: The CPU frequency in KHz, for consistency with CPUFreq
* @power: The power consumed by 1 CPU at this level, in milli-watts
* @cost: The cost coefficient associated with this level, used during
* energy calculation. Equal to: power * max_frequency / frequency
*/
struct em_cap_state {
unsigned long frequency;
unsigned long power;
unsigned long cost;
};
/**
* em_perf_domain - Performance domain
* @table: List of capacity states, in ascending order
* @nr_cap_states: Number of capacity states
* @cpus: Cpumask covering the CPUs of the domain
*
* A "performance domain" represents a group of CPUs whose performance is
* scaled together. All CPUs of a performance domain must have the same
* micro-architecture. Performance domains often have a 1-to-1 mapping with
* CPUFreq policies.
*/
struct em_perf_domain {
struct em_cap_state *table;
int nr_cap_states;
unsigned long cpus[];
};
#ifdef CONFIG_ENERGY_MODEL
#define EM_CPU_MAX_POWER 0xFFFF
struct em_data_callback {
/**
* active_power() - Provide power at the next capacity state of a CPU
* @power : Active power at the capacity state in mW (modified)
* @freq : Frequency at the capacity state in kHz (modified)
* @cpu : CPU for which we do this operation
*
* active_power() must find the lowest capacity state of 'cpu' above
* 'freq' and update 'power' and 'freq' to the matching active power
* and frequency.
*
* The power is the one of a single CPU in the domain, expressed in
* milli-watts. It is expected to fit in the [0, EM_CPU_MAX_POWER]
* range.
*
* Return 0 on success.
*/
int (*active_power)(unsigned long *power, unsigned long *freq, int cpu);
};
#define EM_DATA_CB(_active_power_cb) { .active_power = &_active_power_cb }
struct em_perf_domain *em_cpu_get(int cpu);
int em_register_perf_domain(cpumask_t *span, unsigned int nr_states,
struct em_data_callback *cb);
/**
* em_pd_energy() - Estimates the energy consumed by the CPUs of a perf. domain
* @pd : performance domain for which energy has to be estimated
* @max_util : highest utilization among CPUs of the domain
* @sum_util : sum of the utilization of all CPUs in the domain
*
* Return: the sum of the energy consumed by the CPUs of the domain assuming
* a capacity state satisfying the max utilization of the domain.
*/
static inline unsigned long em_pd_energy(struct em_perf_domain *pd,
unsigned long max_util, unsigned long sum_util)
{
unsigned long freq, scale_cpu;
struct em_cap_state *cs;
int i, cpu;
/*
* In order to predict the capacity state, map the utilization of the
* most utilized CPU of the performance domain to a requested frequency,
* like schedutil.
*/
cpu = cpumask_first(to_cpumask(pd->cpus));
scale_cpu = arch_scale_cpu_capacity(cpu);
cs = &pd->table[pd->nr_cap_states - 1];
freq = map_util_freq(max_util, cs->frequency, scale_cpu);
/*
* Find the lowest capacity state of the Energy Model above the
* requested frequency.
*/
for (i = 0; i < pd->nr_cap_states; i++) {
cs = &pd->table[i];
if (cs->frequency >= freq)
break;
}
/*
* The capacity of a CPU in the domain at that capacity state (cs)
* can be computed as:
*
* cs->freq * scale_cpu
* cs->cap = -------------------- (1)
* cpu_max_freq
*
* So, ignoring the costs of idle states (which are not available in
* the EM), the energy consumed by this CPU at that capacity state is
* estimated as:
*
* cs->power * cpu_util
* cpu_nrg = -------------------- (2)
* cs->cap
*
* since 'cpu_util / cs->cap' represents its percentage of busy time.
*
* NOTE: Although the result of this computation actually is in
* units of power, it can be manipulated as an energy value
* over a scheduling period, since it is assumed to be
* constant during that interval.
*
* By injecting (1) in (2), 'cpu_nrg' can be re-expressed as a product
* of two terms:
*
* cs->power * cpu_max_freq cpu_util
* cpu_nrg = ------------------------ * --------- (3)
* cs->freq scale_cpu
*
* The first term is static, and is stored in the em_cap_state struct
* as 'cs->cost'.
*
* Since all CPUs of the domain have the same micro-architecture, they
* share the same 'cs->cost', and the same CPU capacity. Hence, the
* total energy of the domain (which is the simple sum of the energy of
* all of its CPUs) can be factorized as:
*
* cs->cost * \Sum cpu_util
* pd_nrg = ------------------------ (4)
* scale_cpu
*/
return cs->cost * sum_util / scale_cpu;
}
/**
* em_pd_nr_cap_states() - Get the number of capacity states of a perf. domain
* @pd : performance domain for which this must be done
*
* Return: the number of capacity states in the performance domain table
*/
static inline int em_pd_nr_cap_states(struct em_perf_domain *pd)
{
return pd->nr_cap_states;
}
#else
struct em_data_callback {};
#define EM_DATA_CB(_active_power_cb) { }
static inline int em_register_perf_domain(cpumask_t *span,
unsigned int nr_states, struct em_data_callback *cb)
{
return -EINVAL;
}
static inline struct em_perf_domain *em_cpu_get(int cpu)
{
return NULL;
}
static inline unsigned long em_pd_energy(struct em_perf_domain *pd,
unsigned long max_util, unsigned long sum_util)
{
return 0;
}
static inline int em_pd_nr_cap_states(struct em_perf_domain *pd)
{
return 0;
}
#endif
#endif
|
