Commit e7a1b32e authored by Pierre Gondois's avatar Pierre Gondois Committed by Rafael J. Wysocki
Browse files

cpufreq: Rebuild sched-domains when removing cpufreq driver 



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: default avatarPierre Gondois <pierre.gondois@arm.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 9ef0ad49

drivers/cpufreq/cpufreq.c

+1 −2
Original line number Diff line number Diff line
@@ -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);

include/linux/cpufreq.h

+0 −8
Original line number Diff line number Diff line
@@ -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

kernel/sched/cpufreq_schedutil.c

+29 −26
Original line number Diff line number Diff line
@@ -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