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PM: EM: Add em_dev_compute_costs()

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The device drivers can modify EM at runtime by providing a new EM table.
The EM is used by the EAS and the em_perf_state::cost stores
pre-calculated value to avoid overhead. This patch provides the API for
device drivers to calculate the cost values properly (and not duplicate
the same code).

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Lukasz Luba 2024-02-08 11:55:56 +00:00 committed by Rafael J. Wysocki
parent 24e9fb635d
commit 22ea02848c
2 changed files with 26 additions and 0 deletions
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8
include/linux/energy_model.h
View file

@ -170,6 +170,8 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
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
@ -379,6 +381,12 @@ 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

18
kernel/power/energy_model.c
View file

@ -276,6 +276,24 @@ static int em_compute_costs(struct device *dev, struct em_perf_state *table,
return 0;
}
/**
* em_dev_compute_costs() - Calculate cost values for new runtime EM table
* @dev : Device for which the EM table is to be updated
* @table : The new EM table that is going to get the costs calculated
*
* Calculate the em_perf_state::cost values for new runtime EM table. The
* values are used for EAS during task placement. It also calculates and sets
* the efficiency flag for each performance state. When the function finish
* successfully the EM table is ready to be updated and used by EAS.
*
* Return 0 on success or a proper error in case of failure.
*/
int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
int nr_states)
{
return em_compute_costs(dev, table, NULL, nr_states, 0);
}
/**
* em_dev_update_perf_domain() - Update runtime EM table for a device
* @dev : Device for which the EM is to be updated