diff mbox series

[v5,04/23] PM: EM: Refactor em_pd_get_efficient_state() to be more flexible

Message ID 20231129110853.94344-5-lukasz.luba@arm.com (mailing list archive)
State Changes Requested, archived
Headers show
Series Introduce runtime modifiable Energy Model | expand

Commit Message

Lukasz Luba Nov. 29, 2023, 11:08 a.m. UTC
The Energy Model (EM) is going to support runtime modification. There
are going to be 2 EM tables which store information. This patch aims
to prepare the code to be generic and use one of the tables. The function
will no longer get a pointer to 'struct em_perf_domain' (the EM) but
instead a pointer to 'struct em_perf_state' (which is one of the EM's
tables).

Prepare em_pd_get_efficient_state() for the upcoming changes and
make it possible to re-use. Return an index for the best performance
state for a given EM table. The function arguments that are introduced
should allow to work on different performance state arrays. The caller of
em_pd_get_efficient_state() should be able to use the index either
on the default or the modifiable EM table.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 include/linux/energy_model.h | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

Comments

Dietmar Eggemann Dec. 12, 2023, 6:49 p.m. UTC | #1
On 29/11/2023 12:08, Lukasz Luba wrote:
> The Energy Model (EM) is going to support runtime modification. There
> are going to be 2 EM tables which store information. This patch aims
> to prepare the code to be generic and use one of the tables. The function
> will no longer get a pointer to 'struct em_perf_domain' (the EM) but
> instead a pointer to 'struct em_perf_state' (which is one of the EM's
> tables).
I thought the 2 EM tables design is gone?

IMHO it would be less code changes and hence a more enjoyable review
experience if you would add the 'modifiable' feature to the existing EM
(1) and not add (2) and then remove (1) in [21/23].


 struct em_perf_domain {
-	struct em_perf_state *table;                <-- (1)
 	struct em_perf_table __rcu *runtime_table;  <-- (2)

> Prepare em_pd_get_efficient_state() for the upcoming changes and
> make it possible to re-use. Return an index for the best performance

s/make it possible to re-use/make it possible to be re-used ?

> state for a given EM table. The function arguments that are introduced
> should allow to work on different performance state arrays. The caller of
> em_pd_get_efficient_state() should be able to use the index either
> on the default or the modifiable EM table.
> 
> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
> Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> ---
>  include/linux/energy_model.h | 30 +++++++++++++++++-------------
>  1 file changed, 17 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> index b9caa01dfac4..8069f526c9d8 100644
> --- a/include/linux/energy_model.h
> +++ b/include/linux/energy_model.h
> @@ -175,33 +175,35 @@ void em_dev_unregister_perf_domain(struct device *dev);
>  
>  /**
>   * 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
> + * @state:		List of performance states, in ascending order

(3)

> + * @nr_perf_states:	Number of performance states
> + * @freq:		Frequency 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 @freq
>   * 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 freq, unsigned long pd_flags)

(3) but em_pd_get_efficient_state(struct em_perf_state *table
                                                        ^^^^^
[...]
Lukasz Luba Dec. 19, 2023, 10:58 a.m. UTC | #2
On 12/12/23 18:49, Dietmar Eggemann wrote:
> On 29/11/2023 12:08, Lukasz Luba wrote:
>> The Energy Model (EM) is going to support runtime modification. There
>> are going to be 2 EM tables which store information. This patch aims
>> to prepare the code to be generic and use one of the tables. The function
>> will no longer get a pointer to 'struct em_perf_domain' (the EM) but
>> instead a pointer to 'struct em_perf_state' (which is one of the EM's
>> tables).
> I thought the 2 EM tables design is gone?
> 
> IMHO it would be less code changes and hence a more enjoyable review
> experience if you would add the 'modifiable' feature to the existing EM
> (1) and not add (2) and then remove (1) in [21/23].

I have explained that to some other your email: such approach would
create a patch monster, touching all drivers and frameworks, to just
make sure they still can compile. This is not the right approach.


> 
> 
>   struct em_perf_domain {
> -	struct em_perf_state *table;                <-- (1)
>   	struct em_perf_table __rcu *runtime_table;  <-- (2)
> 
>> Prepare em_pd_get_efficient_state() for the upcoming changes and
>> make it possible to re-use. Return an index for the best performance
> 
> s/make it possible to re-use/make it possible to be re-used ?

OK

> 
>> state for a given EM table. The function arguments that are introduced
>> should allow to work on different performance state arrays. The caller of
>> em_pd_get_efficient_state() should be able to use the index either
>> on the default or the modifiable EM table.
>>
>> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
>> Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> ---
>>   include/linux/energy_model.h | 30 +++++++++++++++++-------------
>>   1 file changed, 17 insertions(+), 13 deletions(-)
>>
>> diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
>> index b9caa01dfac4..8069f526c9d8 100644
>> --- a/include/linux/energy_model.h
>> +++ b/include/linux/energy_model.h
>> @@ -175,33 +175,35 @@ void em_dev_unregister_perf_domain(struct device *dev);
>>   
>>   /**
>>    * 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
>> + * @state:		List of performance states, in ascending order
> 
> (3)
> 
>> + * @nr_perf_states:	Number of performance states
>> + * @freq:		Frequency 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 @freq
>>    * 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 freq, unsigned long pd_flags)
> 
> (3) but em_pd_get_efficient_state(struct em_perf_state *table
>                                                          ^^^^^
> [...]

Good catch, I'll change that.
diff mbox series

Patch

diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index b9caa01dfac4..8069f526c9d8 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -175,33 +175,35 @@  void em_dev_unregister_perf_domain(struct device *dev);
 
 /**
  * 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
+ * @state:		List of performance states, in ascending order
+ * @nr_perf_states:	Number of performance states
+ * @freq:		Frequency 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 @freq
  * 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 freq, unsigned long pd_flags)
 {
 	struct em_perf_state *ps;
 	int i;
 
-	for (i = 0; i < pd->nr_perf_states; i++) {
-		ps = &pd->table[i];
+	for (i = 0; i < nr_perf_states; i++) {
+		ps = &table[i];
 		if (ps->frequency >= freq) {
-			if (pd->flags & EM_PERF_DOMAIN_SKIP_INEFFICIENCIES &&
+			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;
 }
 
 /**
@@ -226,7 +228,7 @@  static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
 {
 	unsigned long freq, scale_cpu;
 	struct em_perf_state *ps;
-	int cpu;
+	int cpu, i;
 
 	if (!sum_util)
 		return 0;
@@ -251,7 +253,9 @@  static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
 	 * Find the lowest performance state of the Energy Model above the
 	 * requested frequency.
 	 */
-	ps = em_pd_get_efficient_state(pd, freq);
+	i = em_pd_get_efficient_state(pd->table, pd->nr_perf_states, freq,
+				      pd->flags);
+	ps = &pd->table[i];
 
 	/*
 	 * The capacity of a CPU in the domain at the performance state (ps)