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Diffstat (limited to 'include/linux/energy_model.h')
| -rw-r--r-- | include/linux/energy_model.h | 425 |
1 files changed, 425 insertions, 0 deletions
diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h new file mode 100644 index 000000000000..43aa6153dc57 --- /dev/null +++ b/include/linux/energy_model.h @@ -0,0 +1,425 @@ +/* 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/kref.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 + * @performance: CPU performance (capacity) at a given frequency + * @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 performance; + 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_table - Performance states table + * @rcu: RCU used for safe access and destruction + * @kref: Reference counter to track the users + * @state: List of performance states, in ascending order + */ +struct em_perf_table { + struct rcu_head rcu; + struct kref kref; + struct em_perf_state state[]; +}; + +/** + * struct em_perf_domain - Performance domain + * @em_table: Pointer to the runtime modifiable em_perf_table + * @node: node in em_pd_list (in energy_model.c) + * @id: A unique ID number for each performance domain + * @nr_perf_states: Number of performance states + * @min_perf_state: Minimum allowed Performance State index + * @max_perf_state: Maximum allowed Performance State index + * @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_table __rcu *em_table; + struct list_head node; + int id; + int nr_perf_states; + int min_perf_state; + int max_perf_state; + 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 + +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_update_perf_domain(struct device *dev, + struct em_perf_table *new_table); +int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, + const struct em_data_callback *cb, + const cpumask_t *cpus, bool microwatts); +int em_dev_register_pd_no_update(struct device *dev, unsigned int nr_states, + const struct em_data_callback *cb, + const cpumask_t *cpus, bool microwatts); +void em_dev_unregister_perf_domain(struct device *dev); +struct em_perf_table *em_table_alloc(struct em_perf_domain *pd); +void em_table_free(struct em_perf_table *table); +int em_dev_compute_costs(struct device *dev, struct em_perf_state *table, + int nr_states); +int em_dev_update_chip_binning(struct device *dev); +int em_update_performance_limits(struct em_perf_domain *pd, + unsigned long freq_min_khz, unsigned long freq_max_khz); +void em_adjust_cpu_capacity(unsigned int cpu); +void em_rebuild_sched_domains(void); + +/** + * em_pd_get_efficient_state() - Get an efficient performance state from the EM + * @table: List of performance states, in ascending order + * @pd: performance domain for which this must be done + * @max_util: Max utilization 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 id, high enough to meet @max_util + * requirement. + */ +static inline int +em_pd_get_efficient_state(struct em_perf_state *table, + struct em_perf_domain *pd, unsigned long max_util) +{ + unsigned long pd_flags = pd->flags; + int min_ps = pd->min_perf_state; + int max_ps = pd->max_perf_state; + struct em_perf_state *ps; + int i; + + for (i = min_ps; i <= max_ps; i++) { + ps = &table[i]; + if (ps->performance >= max_util) { + if (pd_flags & EM_PERF_DOMAIN_SKIP_INEFFICIENCIES && + ps->flags & EM_PERF_STATE_INEFFICIENT) + continue; + return i; + } + } + + return max_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) +{ + struct em_perf_table *em_table; + struct em_perf_state *ps; + int i; + + WARN_ONCE(!rcu_read_lock_held(), "EM: rcu read lock needed\n"); + + 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 + * performance, like schedutil. Take also into account that the real + * performance might be set lower (due to thermal capping). Thus, clamp + * max utilization to the allowed CPU capacity before calculating + * effective performance. + */ + max_util = min(max_util, allowed_cpu_cap); + + /* + * Find the lowest performance state of the Energy Model above the + * requested performance. + */ + em_table = rcu_dereference(pd->em_table); + i = em_pd_get_efficient_state(em_table->state, pd, max_util); + ps = &em_table->state[i]; + + /* + * The performance (capacity) of a CPU in the domain at the performance + * state (ps) can be computed as: + * + * ps->freq * scale_cpu + * ps->performance = -------------------- (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->performance + * + * since 'cpu_util / ps->performance' 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_nrg = ------------------------ * cpu_util (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: + * + * pd_nrg = ps->cost * \Sum cpu_util (4) + */ + return ps->cost * sum_util; +} + +/** + * 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; +} + +/** + * em_perf_state_from_pd() - Get the performance states table of perf. + * domain + * @pd : performance domain for which this must be done + * + * To use this function the rcu_read_lock() should be hold. After the usage + * of the performance states table is finished, the rcu_read_unlock() should + * be called. + * + * Return: the pointer to performance states table of the performance domain + */ +static inline +struct em_perf_state *em_perf_state_from_pd(struct em_perf_domain *pd) +{ + return rcu_dereference(pd->em_table)->state; +} + +#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, + const struct em_data_callback *cb, + const cpumask_t *cpus, bool microwatts) +{ + return -EINVAL; +} +static inline +int em_dev_register_pd_no_update(struct device *dev, unsigned int nr_states, + const struct em_data_callback *cb, + const cpumask_t *cpus, 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; +} +static inline +struct em_perf_table *em_table_alloc(struct em_perf_domain *pd) +{ + return NULL; +} +static inline void em_table_free(struct em_perf_table *table) {} +static inline +int em_dev_update_perf_domain(struct device *dev, + struct em_perf_table *new_table) +{ + return -EINVAL; +} +static inline +struct em_perf_state *em_perf_state_from_pd(struct em_perf_domain *pd) +{ + return NULL; +} +static inline +int em_dev_compute_costs(struct device *dev, struct em_perf_state *table, + int nr_states) +{ + return -EINVAL; +} +static inline int em_dev_update_chip_binning(struct device *dev) +{ + return -EINVAL; +} +static inline +int em_update_performance_limits(struct em_perf_domain *pd, + unsigned long freq_min_khz, unsigned long freq_max_khz) +{ + return -EINVAL; +} +static inline void em_adjust_cpu_capacity(unsigned int cpu) {} +static inline void em_rebuild_sched_domains(void) {} +#endif + +#endif |