diff mbox series

[v2,03/17] PM: EM: Refactor em_pd_get_efficient_state() to be more flexible

Message ID 20230512095743.3393563-4-lukasz.luba@arm.com
State Superseded
Headers show
Series Introduce runtime modifiable Energy Model | expand

Commit Message

Lukasz Luba May 12, 2023, 9:57 a.m. UTC 
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. 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>
---
 include/linux/energy_model.h | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

Comments

Lukasz Luba July 3, 2023, 4:22 p.m. UTC | #1 
On 5/30/23 12:06, Dietmar Eggemann wrote:
> On 12/05/2023 11:57, Lukasz Luba wrote:
>> Prepare em_pd_get_efficient_state() for the upcoming changes and
>> make it possible to re-use. Return an index for the best performance
> 
> Don't get the `possible to re-use`? Did you mean `possible to be
> re-used`? But then `re-used` for what?

The function will no longer get a pointer to 'struct em_perf_domain'
but instead to 'struct em_perf_state'. It would also require to
get the number of states from 'pd->nr_perf_states'.

This is preparation for handling 2 tables:
modifiable (a) and default (b).

Then it also returns and ID not the pointer to state.
It all makes it more generic and ready for those 2 tables.

> 
>> state. 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.
> 
> This describes the WHAT but not the WHY.

I will add that description as 'why' in the header. I wanted to
avoid mentioning in the patch description something which
is coming in the next patch.
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)