Re: [PATCH v2 1/4] PM / EM: add devices to Energy Model

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On 2/13/20 10:59 AM, Dietmar Eggemann wrote:
On 06/02/2020 14:46, lukasz.luba@xxxxxxx wrote:
From: Lukasz Luba <lukasz.luba@xxxxxxx>

[..]

@@ -26,7 +28,7 @@ framework, and interested clients reading the data from it::

s/::/: ?

         | Thermal (IPA) |  | Scheduler (EAS) |  |     Other     |
         +---------------+  +-----------------+  +---------------+
                 |                   | em_pd_energy()    |
-               |                   | em_cpu_get()      |
+               |  em_get_pd()      | em_cpu_get()      |
                 +---------+         |         +---------+

em_get_pd() and em_cpu_get()? Why not em_pd_get()? em_cpu_get() is a
specific em_get_pd(). right?

Yes. I will rename 'em_get_pd' to 'em_pd_get'


[...]

@@ -85,13 +89,20 @@ API.
  2.3 Accessing performance domains
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+There is two API functions which provide the access to the energy model:
+em_cpu_get() which takes CPU id as an argument and em_get_pd() with device
+pointer as an argument. It depends on the subsystem which interface it is
+going to use, but in case of CPU devices both functions return the same
+performance domain.

There is probably a reason why we need this specific function for CPU
devices? The reason should be described. People might ask why
em_get_pd() is not sufficient.

True, good point. I will extend the comment in em_cpu_get().


[...]

- * A "performance domain" represents a group of CPUs whose performance is
- * scaled together. All CPUs of a performance domain must have the same
- * micro-architecture. Performance domains often have a 1-to-1 mapping with
- * CPUFreq policies.
+ * In case of CPU device, a "performance domain" represents a group of CPUs
+ * whose performance is scaled together. All CPUs of a performance domain
+ * must have the same micro-architecture. Performance domains often have
+ * a 1-to-1 mapping with CPUFreq policies.
+ * In case of other devices the 'priv' field is unused.
   */
  struct em_perf_domain {
-	struct em_cap_state *table;
-	int nr_cap_states;
-	unsigned long cpus[0];
+	struct em_perf_state *table;
+	int nr_perf_states;
+	void *priv;

In case you go back to the variable length field plus type field to
distingush EM devices, keep cpus[0] as the name.

OK, I will.


[..]

  /**
- * em_pd_energy() - Estimates the energy consumed by the CPUs of a perf. domain
+ * em_pd_energy() - Estimates the energy consumed by the CPUs of a perf.
+			domain

Why this change?

hmmm, that's odd, maybe there was 'device' then I changed it back to
'CPUs' but forgot to move the 'domain' to the old place.


[...]

@@ -141,12 +210,12 @@ static struct em_perf_domain *em_create_pd(cpumask_t *span, int nr_states,
  		 */
  		opp_eff = freq / power;
  		if (opp_eff >= prev_opp_eff)
-			pr_warn("pd%d: hertz/watts ratio non-monotonically decreasing: em_cap_state %d >= em_cap_state%d\n",
-					cpu, i, i - 1);
+			dev_warn(dev, "energy_model: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",

s/energy_model/EM ?

OK, I will rename them in all places.

Thank you for the review.

Regards,
Lukasz



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