diff options
Diffstat (limited to 'include/linux/energy_model.h')
| -rw-r--r-- | include/linux/energy_model.h | 166 |
1 files changed, 105 insertions, 61 deletions
diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h index 88d91e087471..770755df852f 100644 --- a/include/linux/energy_model.h +++ b/include/linux/energy_model.h @@ -5,6 +5,7 @@ #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> @@ -12,6 +13,7 @@ /** * 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. @@ -20,6 +22,7 @@ * @flags: see "em_perf_state flags" description below. */ struct em_perf_state { + unsigned long performance; unsigned long frequency; unsigned long power; unsigned long cost; @@ -37,8 +40,20 @@ struct em_perf_state { #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 - * @table: List of performance states, in ascending order + * @em_table: Pointer to the runtime modifiable em_perf_table * @nr_perf_states: Number of performance states * @flags: See "em_perf_domain flags" * @cpus: Cpumask covering the CPUs of the domain. It's here @@ -53,7 +68,7 @@ struct em_perf_state { * field is unused. */ struct em_perf_domain { - struct em_perf_state *table; + struct em_perf_table __rcu *em_table; int nr_perf_states; unsigned long flags; unsigned long cpus[]; @@ -98,27 +113,6 @@ struct em_perf_domain { #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 @@ -168,40 +162,48 @@ struct em_data_callback { 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 __rcu *new_table); 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); +struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd); +void em_table_free(struct em_perf_table __rcu *table); +int em_dev_compute_costs(struct device *dev, struct em_perf_state *table, + int nr_states); /** * 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 + * @table: List of performance states, in ascending order + * @nr_perf_states: Number of performance states + * @max_util: Max utilization to map with the EM + * @pd_flags: Performance Domain flags * * 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 + * Return: An efficient performance state id, high enough to meet @max_util * requirement. */ -static inline -struct em_perf_state *em_pd_get_efficient_state(struct em_perf_domain *pd, - unsigned long freq) +static inline int +em_pd_get_efficient_state(struct em_perf_state *table, int nr_perf_states, + unsigned long max_util, unsigned long pd_flags) { 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 && + for (i = 0; i < nr_perf_states; i++) { + ps = &table[i]; + if (ps->performance >= max_util) { + if (pd_flags & EM_PERF_DOMAIN_SKIP_INEFFICIENCIES && ps->flags & EM_PERF_STATE_INEFFICIENT) continue; - break; + return i; } } - return ps; + return nr_perf_states - 1; } /** @@ -224,9 +226,13 @@ 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_table *em_table; struct em_perf_state *ps; - int cpu; + int i; + +#ifdef CONFIG_SCHED_DEBUG + WARN_ONCE(!rcu_read_lock_held(), "EM: rcu read lock needed\n"); +#endif if (!sum_util) return 0; @@ -234,31 +240,30 @@ static inline unsigned long em_cpu_energy(struct em_perf_domain *pd, /* * 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 + * 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 frequency. + * effective performance. */ - cpu = cpumask_first(to_cpumask(pd->cpus)); - scale_cpu = arch_scale_cpu_capacity(cpu); - ref_freq = arch_scale_freq_ref(cpu); - + max_util = map_util_perf(max_util); 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. + * requested performance. */ - ps = em_pd_get_efficient_state(pd, freq); + em_table = rcu_dereference(pd->em_table); + i = em_pd_get_efficient_state(em_table->state, pd->nr_perf_states, + max_util, pd->flags); + ps = &em_table->state[i]; /* - * The capacity of a CPU in the domain at the performance state (ps) - * can be computed as: + * The performance (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 + * 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 @@ -266,9 +271,10 @@ static inline unsigned long em_cpu_energy(struct em_perf_domain *pd, * * ps->power * cpu_util * cpu_nrg = -------------------- (2) - * ps->cap + * ps->performance * - * since 'cpu_util / ps->cap' represents its percentage of busy time. + * 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 @@ -278,9 +284,9 @@ static inline unsigned long em_cpu_energy(struct em_perf_domain *pd, * 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 + * 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'. @@ -290,11 +296,9 @@ static inline unsigned long em_cpu_energy(struct em_perf_domain *pd, * 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 + * pd_nrg = ps->cost * \Sum cpu_util (4) */ - return em_estimate_energy(ps->cost, sum_util, scale_cpu); + return ps->cost * sum_util; } /** @@ -309,6 +313,23 @@ 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) { } @@ -343,6 +364,29 @@ static inline int em_pd_nr_perf_states(struct em_perf_domain *pd) { return 0; } +static inline +struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd) +{ + return NULL; +} +static inline void em_table_free(struct em_perf_table __rcu *table) {} +static inline +int em_dev_update_perf_domain(struct device *dev, + struct em_perf_table __rcu *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; +} #endif #endif |