Commit 772b6539 authored by Dietmar Eggemann's avatar Dietmar Eggemann Committed by Peter Zijlstra
Browse files

sched/deadline: Merge dl_task_can_attach() and dl_cpu_busy() 



Both functions are doing almost the same, that is checking if admission
control is still respected.

With exclusive cpusets, dl_task_can_attach() checks if the destination
cpuset (i.e. its root domain) has enough CPU capacity to accommodate the
task.
dl_cpu_busy() checks if there is enough CPU capacity in the cpuset in
case the CPU is hot-plugged out.

dl_task_can_attach() is used to check if a task can be admitted while
dl_cpu_busy() is used to check if a CPU can be hotplugged out.

Make dl_cpu_busy() able to deal with a task and use it instead of
dl_task_can_attach() in task_can_attach().

Signed-off-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJuri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-4-dietmar.eggemann@arm.com
parent f1304ecb

kernel/sched/core.c

+9 −4
Original line number Diff line number Diff line
@@ -8805,8 +8805,11 @@ int task_can_attach(struct task_struct *p, 
	}



	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,

					      cs_cpus_allowed))

		ret = dl_task_can_attach(p, cs_cpus_allowed);

					      cs_cpus_allowed)) {

		int cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);



		ret = dl_cpu_busy(cpu, p);

	}



out:

	return ret;
@@ -9090,8 +9093,10 @@ static void cpuset_cpu_active(void) 
static int cpuset_cpu_inactive(unsigned int cpu)

{

	if (!cpuhp_tasks_frozen) {

		if (dl_cpu_busy(cpu))

			return -EBUSY;

		int ret = dl_cpu_busy(cpu, NULL);



		if (ret)

			return ret;

		cpuset_update_active_cpus();

	} else {

		num_cpus_frozen++;

kernel/sched/deadline.c

+14 −38
Original line number Diff line number Diff line
@@ -2992,41 +2992,6 @@ bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr) 
}



#ifdef CONFIG_SMP

int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed)

{

	unsigned long flags, cap;

	unsigned int dest_cpu;

	struct dl_bw *dl_b;

	bool overflow;

	int ret;



	dest_cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);



	rcu_read_lock_sched();

	dl_b = dl_bw_of(dest_cpu);

	raw_spin_lock_irqsave(&dl_b->lock, flags);

	cap = dl_bw_capacity(dest_cpu);

	overflow = __dl_overflow(dl_b, cap, 0, p->dl.dl_bw);

	if (overflow) {

		ret = -EBUSY;

	} else {

		/*

		 * We reserve space for this task in the destination

		 * root_domain, as we can't fail after this point.

		 * We will free resources in the source root_domain

		 * later on (see set_cpus_allowed_dl()).

		 */

		int cpus = dl_bw_cpus(dest_cpu);



		__dl_add(dl_b, p->dl.dl_bw, cpus);

		ret = 0;

	}

	raw_spin_unlock_irqrestore(&dl_b->lock, flags);

	rcu_read_unlock_sched();



	return ret;

}



int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,

				 const struct cpumask *trial)

{
@@ -3048,7 +3013,7 @@ int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, 
	return ret;

}



bool dl_cpu_busy(unsigned int cpu)

int dl_cpu_busy(int cpu, struct task_struct *p)

{

	unsigned long flags, cap;

	struct dl_bw *dl_b;
@@ -3058,11 +3023,22 @@ bool dl_cpu_busy(unsigned int cpu) 
	dl_b = dl_bw_of(cpu);

	raw_spin_lock_irqsave(&dl_b->lock, flags);

	cap = dl_bw_capacity(cpu);

	overflow = __dl_overflow(dl_b, cap, 0, 0);

	overflow = __dl_overflow(dl_b, cap, 0, p ? p->dl.dl_bw : 0);



	if (!overflow && p) {

		/*

		 * We reserve space for this task in the destination

		 * root_domain, as we can't fail after this point.

		 * We will free resources in the source root_domain

		 * later on (see set_cpus_allowed_dl()).

		 */

		__dl_add(dl_b, p->dl.dl_bw, dl_bw_cpus(cpu));

	}



	raw_spin_unlock_irqrestore(&dl_b->lock, flags);

	rcu_read_unlock_sched();



	return overflow;

	return overflow ? -EBUSY : 0;

}

#endif

kernel/sched/sched.h

+1 −2
Original line number Diff line number Diff line
@@ -324,9 +324,8 @@ extern void __setparam_dl(struct task_struct *p, const struct sched_attr *attr); 
extern void __getparam_dl(struct task_struct *p, struct sched_attr *attr);

extern bool __checkparam_dl(const struct sched_attr *attr);

extern bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr);

extern int  dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed);

extern int  dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);

extern bool dl_cpu_busy(unsigned int cpu);

extern int  dl_cpu_busy(int cpu, struct task_struct *p);



#ifdef CONFIG_CGROUP_SCHED