[PATCH v1] PM: EM: Move sched domains rebuild function from schedutil to EM

[PATCH v1] PM: EM: Move sched domains rebuild function from schedutil to EM

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Function sugov_eas_rebuild_sd() defined in the schedutil cpufreq governor
implements generic functionality that may be useful in other places.  In
particular, there is a plan to use it in the intel_pstate driver in the
future.

For this reason, move it from schedutil to the energy model code and
rename it to em_rebuild_sched_domains().

This also helps to get rid of some #ifdeffery in schedutil which is a
plus.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

The previous RFC version of this patch is here:

https://lore.kernel.org/linux-pm/2229205.irdbgypaU6@rjwysocki.net/

Changes since the RFC:

 * The new function is called em_rebuild_sched_domains() now.
 * Update the subject and changelog.
 * Reword the comment in sugov_policy_alloc().

---
 drivers/cpufreq/cpufreq.c        |    2 +-
 include/linux/energy_model.h     |    2 ++
 kernel/power/energy_model.c      |   17 +++++++++++++++++
 kernel/sched/cpufreq_schedutil.c |   33 ++++++---------------------------
 4 files changed, 26 insertions(+), 28 deletions(-)

--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1538,7 +1538,7 @@
 
 		/*
 		 * Register with the energy model before
-		 * sugov_eas_rebuild_sd() is called, which will result
+		 * em_rebuild_sched_domains() is called, which will result
 		 * in rebuilding of the sched domains, which should only be done
 		 * once the energy model is properly initialized for the policy
 		 * first.
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -179,6 +179,7 @@
 int em_dev_update_chip_binning(struct device *dev);
 int em_update_performance_limits(struct em_perf_domain *pd,
 		unsigned long freq_min_khz, unsigned long freq_max_khz);
+void em_rebuild_sched_domains(void);
 
 /**
  * em_pd_get_efficient_state() - Get an efficient performance state from the EM
@@ -404,6 +405,7 @@
 {
 	return -EINVAL;
 }
+static inline void em_rebuild_sched_domains(void) {}
 #endif
 
 #endif
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -908,3 +908,20 @@
 	return 0;
 }
 EXPORT_SYMBOL_GPL(em_update_performance_limits);
+
+static void rebuild_sd_workfn(struct work_struct *work)
+{
+	rebuild_sched_domains_energy();
+}
+
+void em_rebuild_sched_domains(void)
+{
+	static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
+
+	/*
+	 * When called from the cpufreq_register_driver() path, the
+	 * cpu_hotplug_lock is already held, so use a work item to
+	 * avoid nested locking in rebuild_sched_domains().
+	 */
+	schedule_work(&rebuild_sd_work);
+}
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -604,31 +604,6 @@
 
 /********************** cpufreq governor interface *********************/
 
-#ifdef CONFIG_ENERGY_MODEL
-static void rebuild_sd_workfn(struct work_struct *work)
-{
-	rebuild_sched_domains_energy();
-}
-
-static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
-
-/*
- * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
- * on governor changes to make sure the scheduler knows about it.
- */
-static void sugov_eas_rebuild_sd(void)
-{
-	/*
-	 * When called from the cpufreq_register_driver() path, the
-	 * cpu_hotplug_lock is already held, so use a work item to
-	 * avoid nested locking in rebuild_sched_domains().
-	 */
-	schedule_work(&rebuild_sd_work);
-}
-#else
-static inline void sugov_eas_rebuild_sd(void) { };
-#endif
-
 struct cpufreq_governor schedutil_gov;
 
 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
@@ -784,7 +759,11 @@
 		goto fail;
 
 out:
-	sugov_eas_rebuild_sd();
+	/*
+	 * Schedutil is the preferred governor for EAS, so rebuild sched domains
+	 * on governor changes to make sure the scheduler knows about them.
+	 */
+	em_rebuild_sched_domains();
 	mutex_unlock(&global_tunables_lock);
 	return 0;
 
@@ -826,7 +805,7 @@
 	sugov_policy_free(sg_policy);
 	cpufreq_disable_fast_switch(policy);
 
-	sugov_eas_rebuild_sd();
+	em_rebuild_sched_domains();
 }
 
 static int sugov_start(struct cpufreq_policy *policy)

Re: [PATCH v1] PM: EM: Move sched domains rebuild function from schedutil to EM

[Christian Loehle]

On 12/12/24 12:01, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Function sugov_eas_rebuild_sd() defined in the schedutil cpufreq governor
> implements generic functionality that may be useful in other places.  In
> particular, there is a plan to use it in the intel_pstate driver in the
> future.
> 
> For this reason, move it from schedutil to the energy model code and
> rename it to em_rebuild_sched_domains().
> 
> This also helps to get rid of some #ifdeffery in schedutil which is a
> plus.
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

As already mentioned during the RFC, fine with me FWIW.
Reviewed-by: Christian Loehle <christian.loehle@arm.com>