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/* 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>
#ifdef CONFIG_ENERGY_MODEL
/**
* 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[0];
};
#define EM_CPU_MAX_POWER 0xFFFF
/*
* Increase resolution of energy estimation calculations for 64-bit
* architectures. The extra resolution improves decision made by EAS for the
* task placement when two Performance Domains might provide similar energy
* estimation values (w/o better resolution the values could be equal).
*
* We increase resolution only if we have enough bits to allow this increased
* resolution (i.e. 64-bit). The costs for increasing resolution when 32-bit
* are pretty high and the returns do not justify the increased costs.
*/
#ifdef CONFIG_64BIT
#define em_scale_power(p) ((p) * 1000)
#else
#define em_scale_power(p) (p)
#endif
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_perf_domain {};
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
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