Commit 15125a22 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched/smp: Use the SMP version of the RT scheduling class 



Simplify the scheduler by making CONFIG_SMP=y primitives and data
structures unconditional in the RT policies scheduler.

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-29-mingo@kernel.org
parent 74063c17

kernel/sched/rt.c

+0 −72
Original line number Diff line number Diff line
@@ -78,12 +78,10 @@ void init_rt_rq(struct rt_rq *rt_rq) 
	/* delimiter for bitsearch: */

	__set_bit(MAX_RT_PRIO, array->bitmap);



#if defined CONFIG_SMP

	rt_rq->highest_prio.curr = MAX_RT_PRIO-1;

	rt_rq->highest_prio.next = MAX_RT_PRIO-1;

	rt_rq->overloaded = 0;

	plist_head_init(&rt_rq->pushable_tasks);

#endif /* CONFIG_SMP */

	/* We start is dequeued state, because no RT tasks are queued */

	rt_rq->rt_queued = 0;
@@ -332,8 +330,6 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) 
}

#endif /* !CONFIG_RT_GROUP_SCHED */



#ifdef CONFIG_SMP



static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)

{

	/* Try to pull RT tasks here if we lower this rq's prio */
@@ -433,21 +429,6 @@ static void dequeue_pushable_task(struct rq *rq, struct task_struct *p) 
	}

}



#else /* !CONFIG_SMP: */



static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)

{

}



static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)

{

}



static inline void rt_queue_push_tasks(struct rq *rq)

{

}

#endif /* !CONFIG_SMP */



static void enqueue_top_rt_rq(struct rt_rq *rt_rq);

static void dequeue_top_rt_rq(struct rt_rq *rt_rq, unsigned int count);
@@ -597,17 +578,10 @@ static int rt_se_boosted(struct sched_rt_entity *rt_se) 
	return p->prio != p->normal_prio;

}



#ifdef CONFIG_SMP

static inline const struct cpumask *sched_rt_period_mask(void)

{

	return this_rq()->rd->span;

}

#else

static inline const struct cpumask *sched_rt_period_mask(void)

{

	return cpu_online_mask;

}

#endif



static inline

struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
@@ -628,7 +602,6 @@ bool sched_rt_bandwidth_account(struct rt_rq *rt_rq) 
		rt_rq->rt_time < rt_b->rt_runtime);

}



#ifdef CONFIG_SMP

/*

 * We ran out of runtime, see if we can borrow some from our neighbours.

 */
@@ -801,9 +774,6 @@ static void balance_runtime(struct rt_rq *rt_rq) 
		raw_spin_lock(&rt_rq->rt_runtime_lock);

	}

}

#else /* !CONFIG_SMP: */

static inline void balance_runtime(struct rt_rq *rt_rq) {}

#endif /* !CONFIG_SMP */



static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)

{
@@ -980,10 +950,8 @@ struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu) 
	return &cpu_rq(cpu)->rt;

}



#ifdef CONFIG_SMP

static void __enable_runtime(struct rq *rq) { }

static void __disable_runtime(struct rq *rq) { }

#endif



#endif /* !CONFIG_RT_GROUP_SCHED */
@@ -1078,8 +1046,6 @@ enqueue_top_rt_rq(struct rt_rq *rt_rq) 
	cpufreq_update_util(rq, 0);

}



#if defined CONFIG_SMP



static void

inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)

{
@@ -1110,16 +1076,6 @@ dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) 
		cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);

}



#else /* !CONFIG_SMP: */



static inline

void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}

static inline

void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}



#endif /* !CONFIG_SMP */



#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED

static void

inc_rt_prio(struct rt_rq *rt_rq, int prio)

{
@@ -1158,13 +1114,6 @@ dec_rt_prio(struct rt_rq *rt_rq, int prio) 
	dec_rt_prio_smp(rt_rq, prio, prev_prio);

}



#else /* !(CONFIG_SMP || CONFIG_RT_GROUP_SCHED): */



static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}

static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}



#endif /* !(CONFIG_SMP || CONFIG_RT_GROUP_SCHED) */



#ifdef CONFIG_RT_GROUP_SCHED



static void
@@ -1541,7 +1490,6 @@ static void yield_task_rt(struct rq *rq) 
	requeue_task_rt(rq, rq->curr, 0);

}



#ifdef CONFIG_SMP

static int find_lowest_rq(struct task_struct *task);



static int
@@ -1656,7 +1604,6 @@ static int balance_rt(struct rq *rq, struct task_struct *p, struct rq_flags *rf) 


	return sched_stop_runnable(rq) || sched_dl_runnable(rq) || sched_rt_runnable(rq);

}

#endif /* CONFIG_SMP */



/*

 * Preempt the current task with a newly woken task if needed:
@@ -1670,7 +1617,6 @@ static void wakeup_preempt_rt(struct rq *rq, struct task_struct *p, int flags) 
		return;

	}



#ifdef CONFIG_SMP

	/*

	 * If:

	 *
@@ -1685,7 +1631,6 @@ static void wakeup_preempt_rt(struct rq *rq, struct task_struct *p, int flags) 
	 */

	if (p->prio == donor->prio && !test_tsk_need_resched(rq->curr))

		check_preempt_equal_prio(rq, p);

#endif /* CONFIG_SMP */

}



static inline void set_next_task_rt(struct rq *rq, struct task_struct *p, bool first)
@@ -1779,8 +1724,6 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p, struct task_s 
		enqueue_pushable_task(rq, p);

}



#ifdef CONFIG_SMP



/* Only try algorithms three times */

#define RT_MAX_TRIES 3
@@ -2454,11 +2397,6 @@ void __init init_sched_rt_class(void) 
					GFP_KERNEL, cpu_to_node(i));

	}

}

#else /* !CONFIG_SMP: */

void __init init_sched_rt_class(void)

{

}

#endif /* !CONFIG_SMP */



/*

 * When switching a task to RT, we may overload the runqueue
@@ -2482,10 +2420,8 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p) 
	 * then see if we can move to another run queue.

	 */

	if (task_on_rq_queued(p)) {

#ifdef CONFIG_SMP

		if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)

			rt_queue_push_tasks(rq);

#endif /* CONFIG_SMP */

		if (p->prio < rq->donor->prio && cpu_online(cpu_of(rq)))

			resched_curr(rq);

	}
@@ -2502,7 +2438,6 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio) 
		return;



	if (task_current_donor(rq, p)) {

#ifdef CONFIG_SMP

		/*

		 * If our priority decreases while running, we

		 * may need to pull tasks to this runqueue.
@@ -2516,11 +2451,6 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio) 
		 */

		if (p->prio > rq->rt.highest_prio.curr)

			resched_curr(rq);

#else /* !CONFIG_SMP: */

		/* For UP simply resched on drop of prio */

		if (oldprio < p->prio)

			resched_curr(rq);

#endif /* !CONFIG_SMP */

	} else {

		/*

		 * This task is not running, but if it is
@@ -2641,7 +2571,6 @@ DEFINE_SCHED_CLASS(rt) = { 
	.put_prev_task		= put_prev_task_rt,

	.set_next_task          = set_next_task_rt,



#ifdef CONFIG_SMP

	.balance		= balance_rt,

	.select_task_rq		= select_task_rq_rt,

	.set_cpus_allowed       = set_cpus_allowed_common,
@@ -2650,7 +2579,6 @@ DEFINE_SCHED_CLASS(rt) = { 
	.task_woken		= task_woken_rt,

	.switched_from		= switched_from_rt,

	.find_lock_rq		= find_lock_lowest_rq,

#endif /* !CONFIG_SMP */



	.task_tick		= task_tick_rt,

kernel/sched/sched.h

+0 −2
Original line number Diff line number Diff line
@@ -792,11 +792,9 @@ struct rt_rq { 
		int		curr; /* highest queued rt task prio */

		int		next; /* next highest */

	} highest_prio;

#ifdef CONFIG_SMP

	bool			overloaded;

	struct plist_head	pushable_tasks;



#endif /* CONFIG_SMP */

	int			rt_queued;



#ifdef CONFIG_RT_GROUP_SCHED