[v4,04/18] PM: EM: Refactor em_pd_get_efficient_state() to be more flexible
Commit Message
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>
---
include/linux/energy_model.h | 30 +++++++++++++++++-------------
1 file changed, 17 insertions(+), 13 deletions(-)
Comments
On 25/09/2023 10:11, 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).
>
> 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>
> ---
[ ... ]
> @@ -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);
nitpicking but s/i/state/
Other than that:
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> + ps = &pd->table[i];
>
> /*
> * The capacity of a CPU in the domain at the performance state (ps)
On 10/23/23 18:39, Daniel Lezcano wrote:
> On 25/09/2023 10:11, 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).
>>
>> 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>
>> ---
>
> [ ... ]
>
>> @@ -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);
>
> nitpicking but s/i/state/
Here it makes sense, I'll try to use 'state', but if that could be a bit
odd in later patches code, where I have:
ps = &runtime_table->state[i];
than:
'->state[state]'
won't fly. Although, let me check, because I'm going to drop the
2 tables design so some fields might get different names.
>
> Other than that:
>
> Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Thanks!
>
>
>> + ps = &pd->table[i];
>> /*
>> * The capacity of a CPU in the domain at the performance state
>> (ps)
>
@@ -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)