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

Rafael J. Wysocki
2024-11-29T16:28:26Z

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