lkml.org 
[lkml]   [2023]   [Apr]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 10/17] PM: EM: Add runtime update interface to modify EM power
From
Hello Lukasz,

On 3/14/23 11:33, Lukasz Luba wrote:
> Add an interface which allows to modify EM power data at runtime.
> The new power information is populated by the provided callback, which
> is called for each performance state. The CPU frequencies' efficiency is
> re-calculated since that might be affected as well. The old EM memory
> is going to be freed later using RCU mechanism.
>
> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
> ---
> include/linux/energy_model.h | 8 +++
> kernel/power/energy_model.c | 109 +++++++++++++++++++++++++++++++++++
> 2 files changed, 117 insertions(+)
>
> diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> index a616006a8130..e1772aa6c843 100644
> --- a/include/linux/energy_model.h
> +++ b/include/linux/energy_model.h
> @@ -202,6 +202,8 @@ 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_data_callback *cb,
> + void *priv);
> int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
> struct em_data_callback *cb, cpumask_t *span,
> bool microwatts);
> @@ -382,6 +384,12 @@ static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
> {
> return 0;
> }
> +static inline
> +int em_dev_update_perf_domain(struct device *dev, struct em_data_callback *cb,
> + void *priv)
> +{
> + return -EINVAL;
> +}
> #endif
>
> #endif
> diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
> index 87962b877376..e0e8fba3d02b 100644
> --- a/kernel/power/energy_model.c
> +++ b/kernel/power/energy_model.c

[snip]

> @@ -531,9 +628,21 @@ void em_dev_unregister_perf_domain(struct device *dev)
>
> tmp = pd->runtime_table;
>
> + /*
> + * Safely destroy runtime modifiable EM. By using the call
> + * synchronize_rcu() we make sure we don't progress till last user
> + * finished the RCU section and our update got applied.
> + */
> rcu_assign_pointer(pd->runtime_table, NULL);
> synchronize_rcu();
>
> + /*
> + * After the sync no updates will be in-flight, so free the old
> + * memory.
> + */
> + if (tmp->state != pd->table)
> + kfree(tmp->state);
> +

NIT: I think that the call 'kfree(pd->default_table->state)' which is done in
the patch:
PM: EM: Refactor struct em_perf_domain and add default_table
should be done here, otherwise this bit of memory is not freed.

Regards,
Pierre


> kfree(tmp);
>
> kfree(dev->em_pd->table);

\
 
 \ /
  Last update: 2023-04-11 17:41    [W:0.171 / U:0.536 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site