Commit 93940fbd authored by Christian Loehle's avatar Christian Loehle Committed by Rafael J. Wysocki
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cpufreq/schedutil: Only bind threads if needed 



Remove the unconditional binding of sugov kthreads to the affected CPUs
if the cpufreq driver indicates that updates can happen from any CPU.
This allows userspace to set affinities to either save power (waking up
bigger CPUs on HMP can be expensive) or increasing performance (by
letting the utilized CPUs run without preemption of the sugov kthread).

Signed-off-by: default avatarChristian Loehle <christian.loehle@arm.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Acked-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Acked-by: default avatarRafael J. Wysocki <rafael@kernel.org>
Acked-by: default avatarJuri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/5a8deed4-7764-4729-a9d4-9520c25fa7e8@arm.com


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 2b16c631

kernel/sched/cpufreq_schedutil.c

+5 −1
Original line number Diff line number Diff line
@@ -666,7 +666,11 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy) 
	}



	sg_policy->thread = thread;

	if (policy->dvfs_possible_from_any_cpu)

		set_cpus_allowed_ptr(thread, policy->related_cpus);

	else

		kthread_bind_mask(thread, policy->related_cpus);



	init_irq_work(&sg_policy->irq_work, sugov_irq_work);

	mutex_init(&sg_policy->work_lock);

kernel/sched/syscalls.c

+7 −0
Original line number Diff line number Diff line
@@ -1129,6 +1129,13 @@ int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask) 
	if (!task_has_dl_policy(p) || !dl_bandwidth_enabled())

		return 0;



	/*

	 * The special/sugov task isn't part of regular bandwidth/admission

	 * control so let userspace change affinities.

	 */

	if (dl_entity_is_special(&p->dl))

		return 0;



	/*

	 * Since bandwidth control happens on root_domain basis,

	 * if admission test is enabled, we only admit -deadline