linux-kernel - [RFC][PATCH v021 3/9] PM: EM: Move perf rebuilding function from schedutil to EM

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Message-ID: <2229205.irdbgypaU6@rjwysocki.net>
Date: Fri, 29 Nov 2024 16:59:06 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Lukasz Luba <lukasz.luba@....com>,
 Peter Zijlstra <peterz@...radead.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 Dietmar Eggemann <dietmar.eggemann@....com>,
 Morten Rasmussen <morten.rasmussen@....com>,
 Vincent Guittot <vincent.guittot@...aro.org>,
 Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
 Pierre Gondois <pierre.gondois@....com>
Subject:
 [RFC][PATCH v021 3/9] PM: EM: Move perf rebuilding function from schedutil to
 EM

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

The sugov_eas_rebuild_sd() function defined in the schedutil cpufreq
governor implements generic functionality that may be useful in other
places.  In particular, going forward it will be used in the intel_pstate
driver.

For this reason, move it from schedutil to the energy model code and
rename it to em_rebuild_perf_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@...el.com>
---

v0.1 -> v0.2:
     * Update the comment regarding :register_em() in cpufreq.
     * Changelog edits.

---
 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(-)

Index: linux-pm/kernel/power/energy_model.c
===================================================================
--- linux-pm.orig/kernel/power/energy_model.c
+++ linux-pm/kernel/power/energy_model.c
@@ -908,3 +908,20 @@ int em_update_performance_limits(struct
 	return 0;
 }
 EXPORT_SYMBOL_GPL(em_update_performance_limits);
+
+static void rebuild_sd_workfn(struct work_struct *work)
+{
+	rebuild_sched_domains_energy();
+}
+
+static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
+
+void em_rebuild_perf_domains(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);
+}
Index: linux-pm/kernel/sched/cpufreq_schedutil.c
===================================================================
--- linux-pm.orig/kernel/sched/cpufreq_schedutil.c
+++ linux-pm/kernel/sched/cpufreq_schedutil.c
@@ -604,31 +604,6 @@ static const struct kobj_type sugov_tuna
 
 /********************** 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 @@ static int sugov_init(struct cpufreq_pol
 		goto fail;
 
 out:
-	sugov_eas_rebuild_sd();
+	/*
+	 * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
+	 * on governor changes to make sure the scheduler knows about them.
+	 */
+	em_rebuild_perf_domains();
 	mutex_unlock(&global_tunables_lock);
 	return 0;
 
@@ -826,7 +805,7 @@ static void sugov_exit(struct cpufreq_po
 	sugov_policy_free(sg_policy);
 	cpufreq_disable_fast_switch(policy);
 
-	sugov_eas_rebuild_sd();
+	em_rebuild_perf_domains();
 }
 
 static int sugov_start(struct cpufreq_policy *policy)
Index: linux-pm/include/linux/energy_model.h
===================================================================
--- linux-pm.orig/include/linux/energy_model.h
+++ linux-pm/include/linux/energy_model.h
@@ -179,6 +179,7 @@ int em_dev_compute_costs(struct device *
 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_perf_domains(void);
 
 /**
  * em_pd_get_efficient_state() - Get an efficient performance state from the EM
@@ -404,6 +405,7 @@ int em_update_performance_limits(struct
 {
 	return -EINVAL;
 }
+static inline void em_rebuild_perf_domains(void) {}
 #endif
 
 #endif
Index: linux-pm/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq.c
+++ linux-pm/drivers/cpufreq/cpufreq.c
@@ -1538,7 +1538,7 @@ static int cpufreq_online(unsigned int c
 
 		/*
 		 * Register with the energy model before
-		 * sugov_eas_rebuild_sd() is called, which will result
+		 * em_rebuild_perf_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.