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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/device.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>
/**
* struct em_perf_state - Performance state of a performance domain
* @frequency: The frequency in KHz, for consistency with CPUFreq
* @power: The power consumed at this level (by 1 CPU or by a registered
* device). It can be a total power: static and dynamic.
* @cost: The cost coefficient associated with this level, used during
* energy calculation. Equal to: power * max_frequency / frequency
* @flags: see "em_perf_state flags" description below.
*/
struct em_perf_state {
unsigned long frequency;
unsigned long power;
unsigned long cost;
unsigned long flags;
};
/*
* em_perf_state flags:
*
* EM_PERF_STATE_INEFFICIENT: The performance state is inefficient. There is
* in this em_perf_domain, another performance state with a higher frequency
* but a lower or equal power cost. Such inefficient states are ignored when
* using em_pd_get_efficient_*() functions.
*/
#define EM_PERF_STATE_INEFFICIENT BIT(0)
/**
* struct em_perf_domain - Performance domain
* @table: List of performance states, in ascending order
* @nr_perf_states: Number of performance states
* @flags: See "em_perf_domain flags"
* @cpus: Cpumask covering the CPUs of the domain. It's here
* for performance reasons to avoid potential cache
* misses during energy calculations in the scheduler
* and simplifies allocating/freeing that memory region.
*
* In case of CPU device, 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. In case of other devices the @cpus
* field is unused.
*/
struct em_perf_domain {
struct em_perf_state *table;
int nr_perf_states;
unsigned long flags;
unsigned long cpus[];
};
/*
* em_perf_domain flags:
*
* EM_PERF_DOMAIN_MICROWATTS: The power values are in micro-Watts or some
* other scale.
*
* EM_PERF_DOMAIN_SKIP_INEFFICIENCIES: Skip inefficient states when estimating
* energy consumption.
*
* EM_PERF_DOMAIN_ARTIFICIAL: The power values are artificial and might be
* created by platform missing real power information
*/
#define EM_PERF_DOMAIN_MICROWATTS BIT(0)
#define EM_PERF_DOMAIN_SKIP_INEFFICIENCIES BIT(1)
#define EM_PERF_DOMAIN_ARTIFICIAL BIT(2)
#define em_span_cpus(em) (to_cpumask((em)->cpus))
#define em_is_artificial(em) ((em)->flags & EM_PERF_DOMAIN_ARTIFICIAL)
#ifdef CONFIG_ENERGY_MODEL
/*
* The max power value in micro-Watts. The limit of 64 Watts is set as
* a safety net to not overflow multiplications on 32bit platforms. The
* 32bit value limit for total Perf Domain power implies a limit of
* maximum CPUs in such domain to 64.
*/
#define EM_MAX_POWER (64000000) /* 64 Watts */
/*
* To avoid possible energy estimation overflow on 32bit machines add
* limits to number of CPUs in the Perf. Domain.
* We are safe on 64bit machine, thus some big number.
*/
#ifdef CONFIG_64BIT
#define EM_MAX_NUM_CPUS 4096
#else
#define EM_MAX_NUM_CPUS 16
#endif
/*
* To avoid an overflow on 32bit machines while calculating the energy
* use a different order in the operation. First divide by the 'cpu_scale'
* which would reduce big value stored in the 'cost' field, then multiply by
* the 'sum_util'. This would allow to handle existing platforms, which have
* e.g. power ~1.3 Watt at max freq, so the 'cost' value > 1mln micro-Watts.
* In such scenario, where there are 4 CPUs in the Perf. Domain the 'sum_util'
* could be 4096, then multiplication: 'cost' * 'sum_util' would overflow.
* This reordering of operations has some limitations, we lose small
* precision in the estimation (comparing to 64bit platform w/o reordering).
*
* We are safe on 64bit machine.
*/
#ifdef CONFIG_64BIT
#define em_estimate_energy(cost, sum_util, scale_cpu) \
(((cost) * (sum_util)) / (scale_cpu))
#else
#define em_estimate_energy(cost, sum_util, scale_cpu) \
(((cost) / (scale_cpu)) * (sum_util))
#endif
struct em_data_callback {
/**
* active_power() - Provide power at the next performance state of
* a device
* @dev : Device for which we do this operation (can be a CPU)
* @power : Active power at the performance state
* (modified)
* @freq : Frequency at the performance state in kHz
* (modified)
*
* active_power() must find the lowest performance state of 'dev' above
* 'freq' and update 'power' and 'freq' to the matching active power
* and frequency.
*
* In case of CPUs, the power is the one of a single CPU in the domain,
* expressed in micro-Watts or an abstract scale. It is expected to
* fit in the [0, EM_MAX_POWER] range.
*
* Return 0 on success.
*/
int (*active_power)(struct device *dev, unsigned long *power,
unsigned long *freq);
/**
* get_cost() - Provide the cost at the given performance state of
* a device
* @dev : Device for which we do this operation (can be a CPU)
* @freq : Frequency at the performance state in kHz
* @cost : The cost value for the performance state
* (modified)
*
* In case of CPUs, the cost is the one of a single CPU in the domain.
* It is expected to fit in the [0, EM_MAX_POWER] range due to internal
* usage in EAS calculation.
*
* Return 0 on success, or appropriate error value in case of failure.
*/
int (*get_cost)(struct device *dev, unsigned long freq,
unsigned long *cost);
};
#define EM_SET_ACTIVE_POWER_CB(em_cb, cb) ((em_cb).active_power = cb)
#define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) \
{ .active_power = _active_power_cb, \
.get_cost = _cost_cb }
#define EM_DATA_CB(_active_power_cb) \
EM_ADV_DATA_CB(_active_power_cb, NULL)
struct em_perf_domain *em_cpu_get(int cpu);
struct em_perf_domain *em_pd_get(struct device *dev);
int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
struct em_data_callback *cb, cpumask_t *span,
bool microwatts);
void em_dev_unregister_perf_domain(struct device *dev);
/**
* em_pd_get_efficient_state() - Get an efficient performance state from the EM
* @pd : Performance domain for which we want an efficient frequency
* @freq : Frequency to map with the EM
*
* It is called from the scheduler code quite frequently and as a consequence
* doesn't implement any check.
*
* Return: An efficient performance state, high enough to meet @freq
* requirement.
*/
static inline
struct em_perf_state *em_pd_get_efficient_state(struct em_perf_domain *pd,
unsigned long freq)
{
struct em_perf_state *ps;
int i;
for (i = 0; i < pd->nr_perf_states; i++) {
ps = &pd->table[i];
if (ps->frequency >= freq) {
if (pd->flags & EM_PERF_DOMAIN_SKIP_INEFFICIENCIES &&
ps->flags & EM_PERF_STATE_INEFFICIENT)
continue;
break;
}
}
return ps;
}
/**
* em_cpu_energy() - Estimates the energy consumed by the CPUs of a
* performance 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
* @allowed_cpu_cap : maximum allowed CPU capacity for the @pd, which
* might reflect reduced frequency (due to thermal)
*
* This function must be used only for CPU devices. There is no validation,
* i.e. if the EM is a CPU type and has cpumask allocated. It is called from
* the scheduler code quite frequently and that is why there is not checks.
*
* 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_cpu_energy(struct em_perf_domain *pd,
unsigned long max_util, unsigned long sum_util,
unsigned long allowed_cpu_cap)
{
unsigned long freq, ref_freq, scale_cpu;
struct em_perf_state *ps;
int cpu;
if (!sum_util)
return 0;
/*
* In order to predict the performance state, map the utilization of
* the most utilized CPU of the performance domain to a requested
* frequency, like schedutil. Take also into account that the real
* frequency might be set lower (due to thermal capping). Thus, clamp
* max utilization to the allowed CPU capacity before calculating
* effective frequency.
*/
cpu = cpumask_first(to_cpumask(pd->cpus));
scale_cpu = arch_scale_cpu_capacity(cpu);
ref_freq = arch_scale_freq_ref(cpu);
max_util = min(max_util, allowed_cpu_cap);
freq = map_util_freq(max_util, ref_freq, scale_cpu);
/*
* Find the lowest performance state of the Energy Model above the
* requested frequency.
*/
ps = em_pd_get_efficient_state(pd, freq);
/*
* The capacity of a CPU in the domain at the performance state (ps)
* can be computed as:
*
* ps->freq * scale_cpu
* ps->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 performance state
* is estimated as:
*
* ps->power * cpu_util
* cpu_nrg = -------------------- (2)
* ps->cap
*
* since 'cpu_util / ps->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:
*
* ps->power * cpu_max_freq cpu_util
* cpu_nrg = ------------------------ * --------- (3)
* ps->freq scale_cpu
*
* The first term is static, and is stored in the em_perf_state struct
* as 'ps->cost'.
*
* Since all CPUs of the domain have the same micro-architecture, they
* share the same 'ps->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:
*
* ps->cost * \Sum cpu_util
* pd_nrg = ------------------------ (4)
* scale_cpu
*/
return em_estimate_energy(ps->cost, sum_util, scale_cpu);
}
/**
* em_pd_nr_perf_states() - Get the number of performance states of a perf.
* domain
* @pd : performance domain for which this must be done
*
* Return: the number of performance states in the performance domain table
*/
static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
{
return pd->nr_perf_states;
}
#else
struct em_data_callback {};
#define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) { }
#define EM_DATA_CB(_active_power_cb) { }
#define EM_SET_ACTIVE_POWER_CB(em_cb, cb) do { } while (0)
static inline
int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
struct em_data_callback *cb, cpumask_t *span,
bool microwatts)
{
return -EINVAL;
}
static inline void em_dev_unregister_perf_domain(struct device *dev)
{
}
static inline struct em_perf_domain *em_cpu_get(int cpu)
{
return NULL;
}
static inline struct em_perf_domain *em_pd_get(struct device *dev)
{
return NULL;
}
static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
unsigned long max_util, unsigned long sum_util,
unsigned long allowed_cpu_cap)
{
return 0;
}
static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
{
return 0;
}
#endif
#endif
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