350 lines
12 KiB
C
350 lines
12 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_ENERGY_MODEL_H
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#define _LINUX_ENERGY_MODEL_H
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#include <linux/cpumask.h>
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#include <linux/device.h>
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#include <linux/jump_label.h>
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#include <linux/kobject.h>
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#include <linux/rcupdate.h>
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#include <linux/sched/cpufreq.h>
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#include <linux/sched/topology.h>
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#include <linux/types.h>
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/**
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* struct em_perf_state - Performance state of a performance domain
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* @frequency: The frequency in KHz, for consistency with CPUFreq
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* @power: The power consumed at this level (by 1 CPU or by a registered
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* device). It can be a total power: static and dynamic.
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* @cost: The cost coefficient associated with this level, used during
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* energy calculation. Equal to: power * max_frequency / frequency
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* @flags: see "em_perf_state flags" description below.
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*/
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struct em_perf_state {
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unsigned long frequency;
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unsigned long power;
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unsigned long cost;
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unsigned long flags;
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};
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/*
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* em_perf_state flags:
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*
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* EM_PERF_STATE_INEFFICIENT: The performance state is inefficient. There is
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* in this em_perf_domain, another performance state with a higher frequency
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* but a lower or equal power cost. Such inefficient states are ignored when
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* using em_pd_get_efficient_*() functions.
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*/
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#define EM_PERF_STATE_INEFFICIENT BIT(0)
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/**
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* struct em_perf_domain - Performance domain
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* @table: List of performance states, in ascending order
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* @nr_perf_states: Number of performance states
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* @flags: See "em_perf_domain flags"
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* @cpus: Cpumask covering the CPUs of the domain. It's here
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* for performance reasons to avoid potential cache
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* misses during energy calculations in the scheduler
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* and simplifies allocating/freeing that memory region.
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*
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* In case of CPU device, a "performance domain" represents a group of CPUs
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* whose performance is scaled together. All CPUs of a performance domain
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* must have the same micro-architecture. Performance domains often have
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* a 1-to-1 mapping with CPUFreq policies. In case of other devices the @cpus
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* field is unused.
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*/
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struct em_perf_domain {
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struct em_perf_state *table;
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int nr_perf_states;
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unsigned long flags;
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unsigned long cpus[];
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};
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/*
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* em_perf_domain flags:
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*
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* EM_PERF_DOMAIN_MICROWATTS: The power values are in micro-Watts or some
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* other scale.
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*
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* EM_PERF_DOMAIN_SKIP_INEFFICIENCIES: Skip inefficient states when estimating
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* energy consumption.
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*
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* EM_PERF_DOMAIN_ARTIFICIAL: The power values are artificial and might be
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* created by platform missing real power information
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*/
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#define EM_PERF_DOMAIN_MICROWATTS BIT(0)
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#define EM_PERF_DOMAIN_SKIP_INEFFICIENCIES BIT(1)
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#define EM_PERF_DOMAIN_ARTIFICIAL BIT(2)
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#define em_span_cpus(em) (to_cpumask((em)->cpus))
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#define em_is_artificial(em) ((em)->flags & EM_PERF_DOMAIN_ARTIFICIAL)
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#ifdef CONFIG_ENERGY_MODEL
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/*
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* The max power value in micro-Watts. The limit of 64 Watts is set as
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* a safety net to not overflow multiplications on 32bit platforms. The
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* 32bit value limit for total Perf Domain power implies a limit of
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* maximum CPUs in such domain to 64.
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*/
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#define EM_MAX_POWER (64000000) /* 64 Watts */
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/*
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* To avoid possible energy estimation overflow on 32bit machines add
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* limits to number of CPUs in the Perf. Domain.
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* We are safe on 64bit machine, thus some big number.
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*/
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#ifdef CONFIG_64BIT
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#define EM_MAX_NUM_CPUS 4096
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#else
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#define EM_MAX_NUM_CPUS 16
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#endif
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/*
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* To avoid an overflow on 32bit machines while calculating the energy
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* use a different order in the operation. First divide by the 'cpu_scale'
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* which would reduce big value stored in the 'cost' field, then multiply by
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* the 'sum_util'. This would allow to handle existing platforms, which have
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* e.g. power ~1.3 Watt at max freq, so the 'cost' value > 1mln micro-Watts.
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* In such scenario, where there are 4 CPUs in the Perf. Domain the 'sum_util'
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* could be 4096, then multiplication: 'cost' * 'sum_util' would overflow.
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* This reordering of operations has some limitations, we lose small
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* precision in the estimation (comparing to 64bit platform w/o reordering).
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*
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* We are safe on 64bit machine.
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*/
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#ifdef CONFIG_64BIT
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#define em_estimate_energy(cost, sum_util, scale_cpu) \
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(((cost) * (sum_util)) / (scale_cpu))
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#else
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#define em_estimate_energy(cost, sum_util, scale_cpu) \
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(((cost) / (scale_cpu)) * (sum_util))
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#endif
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struct em_data_callback {
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/**
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* active_power() - Provide power at the next performance state of
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* a device
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* @dev : Device for which we do this operation (can be a CPU)
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* @power : Active power at the performance state
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* (modified)
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* @freq : Frequency at the performance state in kHz
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* (modified)
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*
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* active_power() must find the lowest performance state of 'dev' above
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* 'freq' and update 'power' and 'freq' to the matching active power
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* and frequency.
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*
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* In case of CPUs, the power is the one of a single CPU in the domain,
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* expressed in micro-Watts or an abstract scale. It is expected to
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* fit in the [0, EM_MAX_POWER] range.
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*
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* Return 0 on success.
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*/
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int (*active_power)(struct device *dev, unsigned long *power,
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unsigned long *freq);
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/**
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* get_cost() - Provide the cost at the given performance state of
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* a device
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* @dev : Device for which we do this operation (can be a CPU)
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* @freq : Frequency at the performance state in kHz
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* @cost : The cost value for the performance state
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* (modified)
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*
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* In case of CPUs, the cost is the one of a single CPU in the domain.
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* It is expected to fit in the [0, EM_MAX_POWER] range due to internal
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* usage in EAS calculation.
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*
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* Return 0 on success, or appropriate error value in case of failure.
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*/
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int (*get_cost)(struct device *dev, unsigned long freq,
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unsigned long *cost);
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};
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#define EM_SET_ACTIVE_POWER_CB(em_cb, cb) ((em_cb).active_power = cb)
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#define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) \
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{ .active_power = _active_power_cb, \
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.get_cost = _cost_cb }
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#define EM_DATA_CB(_active_power_cb) \
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EM_ADV_DATA_CB(_active_power_cb, NULL)
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struct em_perf_domain *em_cpu_get(int cpu);
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struct em_perf_domain *em_pd_get(struct device *dev);
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int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
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struct em_data_callback *cb, cpumask_t *span,
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bool microwatts);
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void em_dev_unregister_perf_domain(struct device *dev);
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/**
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* em_pd_get_efficient_state() - Get an efficient performance state from the EM
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* @pd : Performance domain for which we want an efficient frequency
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* @freq : Frequency to map with the EM
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*
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* It is called from the scheduler code quite frequently and as a consequence
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* doesn't implement any check.
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*
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* Return: An efficient performance state, high enough to meet @freq
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* requirement.
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*/
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static inline
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struct em_perf_state *em_pd_get_efficient_state(struct em_perf_domain *pd,
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unsigned long freq)
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{
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struct em_perf_state *ps;
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int i;
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for (i = 0; i < pd->nr_perf_states; i++) {
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ps = &pd->table[i];
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if (ps->frequency >= freq) {
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if (pd->flags & EM_PERF_DOMAIN_SKIP_INEFFICIENCIES &&
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ps->flags & EM_PERF_STATE_INEFFICIENT)
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continue;
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break;
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}
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}
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return ps;
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}
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/**
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* em_cpu_energy() - Estimates the energy consumed by the CPUs of a
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* performance domain
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* @pd : performance domain for which energy has to be estimated
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* @max_util : highest utilization among CPUs of the domain
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* @sum_util : sum of the utilization of all CPUs in the domain
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* @allowed_cpu_cap : maximum allowed CPU capacity for the @pd, which
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* might reflect reduced frequency (due to thermal)
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*
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* This function must be used only for CPU devices. There is no validation,
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* i.e. if the EM is a CPU type and has cpumask allocated. It is called from
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* the scheduler code quite frequently and that is why there is not checks.
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*
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* Return: the sum of the energy consumed by the CPUs of the domain assuming
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* a capacity state satisfying the max utilization of the domain.
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*/
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static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
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unsigned long max_util, unsigned long sum_util,
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unsigned long allowed_cpu_cap)
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{
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unsigned long freq, scale_cpu;
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struct em_perf_state *ps;
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int cpu;
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if (!sum_util)
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return 0;
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/*
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* In order to predict the performance state, map the utilization of
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* the most utilized CPU of the performance domain to a requested
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* frequency, like schedutil. Take also into account that the real
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* frequency might be set lower (due to thermal capping). Thus, clamp
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* max utilization to the allowed CPU capacity before calculating
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* effective frequency.
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*/
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cpu = cpumask_first(to_cpumask(pd->cpus));
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scale_cpu = arch_scale_cpu_capacity(cpu);
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ps = &pd->table[pd->nr_perf_states - 1];
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max_util = map_util_perf(max_util);
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max_util = min(max_util, allowed_cpu_cap);
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freq = map_util_freq(max_util, ps->frequency, scale_cpu);
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/*
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* Find the lowest performance state of the Energy Model above the
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* requested frequency.
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*/
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ps = em_pd_get_efficient_state(pd, freq);
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/*
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* The capacity of a CPU in the domain at the performance state (ps)
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* can be computed as:
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*
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* ps->freq * scale_cpu
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* ps->cap = -------------------- (1)
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* cpu_max_freq
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*
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* So, ignoring the costs of idle states (which are not available in
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* the EM), the energy consumed by this CPU at that performance state
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* is estimated as:
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*
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* ps->power * cpu_util
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* cpu_nrg = -------------------- (2)
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* ps->cap
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*
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* since 'cpu_util / ps->cap' represents its percentage of busy time.
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*
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* NOTE: Although the result of this computation actually is in
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* units of power, it can be manipulated as an energy value
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* over a scheduling period, since it is assumed to be
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* constant during that interval.
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*
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* By injecting (1) in (2), 'cpu_nrg' can be re-expressed as a product
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* of two terms:
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*
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* ps->power * cpu_max_freq cpu_util
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* cpu_nrg = ------------------------ * --------- (3)
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* ps->freq scale_cpu
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*
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* The first term is static, and is stored in the em_perf_state struct
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* as 'ps->cost'.
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*
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* Since all CPUs of the domain have the same micro-architecture, they
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* share the same 'ps->cost', and the same CPU capacity. Hence, the
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* total energy of the domain (which is the simple sum of the energy of
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* all of its CPUs) can be factorized as:
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*
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* ps->cost * \Sum cpu_util
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* pd_nrg = ------------------------ (4)
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* scale_cpu
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*/
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return em_estimate_energy(ps->cost, sum_util, scale_cpu);
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}
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/**
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* em_pd_nr_perf_states() - Get the number of performance states of a perf.
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* domain
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* @pd : performance domain for which this must be done
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*
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* Return: the number of performance states in the performance domain table
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*/
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static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
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{
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return pd->nr_perf_states;
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}
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#else
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struct em_data_callback {};
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#define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) { }
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#define EM_DATA_CB(_active_power_cb) { }
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#define EM_SET_ACTIVE_POWER_CB(em_cb, cb) do { } while (0)
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static inline
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int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
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struct em_data_callback *cb, cpumask_t *span,
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bool microwatts)
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{
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return -EINVAL;
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}
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static inline void em_dev_unregister_perf_domain(struct device *dev)
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{
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}
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static inline struct em_perf_domain *em_cpu_get(int cpu)
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{
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return NULL;
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}
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static inline struct em_perf_domain *em_pd_get(struct device *dev)
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{
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return NULL;
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}
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static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
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unsigned long max_util, unsigned long sum_util,
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unsigned long allowed_cpu_cap)
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{
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return 0;
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}
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static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
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{
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return 0;
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}
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#endif
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#endif
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