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

Lukasz Luba
2023-11-29T11:08:28Z

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(-)

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)
--
2.25.1