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cpufreq/schedutil: Only bind threads if needed

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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: Christian Loehle <christian.loehle@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/5a8deed4-7764-4729-a9d4-9520c25fa7e8@arm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Christian Loehle 2025-01-20 10:09:46 +00:00 committed by Rafael J. Wysocki
parent 2b16c63183
commit 93940fbdc4
2 changed files with 12 additions and 1 deletions
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6
kernel/sched/cpufreq_schedutil.c
View File

@ -666,7 +666,11 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy)
}
sg_policy->thread = thread;
kthread_bind_mask(thread, policy->related_cpus);
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);

7
kernel/sched/syscalls.c
View File

@ -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