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cpufreq: Rebuild sched-domains when removing cpufreq driver

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The Energy Aware Scheduler (EAS) relies on the schedutil governor.
When moving to/from the schedutil governor, sched domains must be
rebuilt to allow re-evaluating the enablement conditions of EAS.
This is done through sched_cpufreq_governor_change().

Having a cpufreq governor assumes a cpufreq driver is running.
Inserting/removing a cpufreq driver should trigger a re-evaluation
of EAS enablement conditions, avoiding to see EAS enabled when
removing a running cpufreq driver.

Rebuild the sched domains in schedutil's sugov_init()/sugov_exit(),
allowing to check EAS's enablement condition whenever schedutil
governor is initialized/exited from.
Move relevant code up in schedutil.c to avoid a split and conditional
function declaration.
Rename sched_cpufreq_governor_change() to sugov_eas_rebuild_sd().

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Pierre Gondois 2023-10-05 15:41:20 +02:00 committed by Rafael J. Wysocki
parent 9ef0ad49cc
commit e7a1b32e43
3 changed files with 30 additions and 36 deletions
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3
drivers/cpufreq/cpufreq.c
View File

@ -1544,7 +1544,7 @@ static int cpufreq_online(unsigned int cpu)
/*
* Register with the energy model before
* sched_cpufreq_governor_change() is called, which will result
* sugov_eas_rebuild_sd() 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.
@ -2652,7 +2652,6 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
ret = cpufreq_start_governor(policy);
if (!ret) {
pr_debug("governor change\n");
sched_cpufreq_governor_change(policy, old_gov);
return 0;
}
cpufreq_exit_governor(policy);

8
include/linux/cpufreq.h
View File

@ -1193,14 +1193,6 @@ static inline int of_perf_domain_get_sharing_cpumask(int pcpu, const char *list_
}
#endif
#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
struct cpufreq_governor *old_gov);
#else
static inline void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
struct cpufreq_governor *old_gov) { }
#endif
extern unsigned int arch_freq_get_on_cpu(int cpu);
#ifndef arch_set_freq_scale

55
kernel/sched/cpufreq_schedutil.c
View File

@ -555,6 +555,31 @@ static const struct kobj_type sugov_tunables_ktype = {
/********************** 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)
@ -709,6 +734,8 @@ static int sugov_init(struct cpufreq_policy *policy)
if (ret)
goto fail;
sugov_eas_rebuild_sd();
out:
mutex_unlock(&global_tunables_lock);
return 0;
@ -750,6 +777,8 @@ static void sugov_exit(struct cpufreq_policy *policy)
sugov_kthread_stop(sg_policy);
sugov_policy_free(sg_policy);
cpufreq_disable_fast_switch(policy);
sugov_eas_rebuild_sd();
}
static int sugov_start(struct cpufreq_policy *policy)
@ -833,29 +862,3 @@ struct cpufreq_governor *cpufreq_default_governor(void)
#endif
cpufreq_governor_init(schedutil_gov);
#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.
*/
void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
struct cpufreq_governor *old_gov)
{
if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
/*
* 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);
}
}
#endif