Commit 5b726e9b authored by Aaron Lu's avatar Aaron Lu Committed by Peter Zijlstra
Browse files

sched/fair: Get rid of throttled_lb_pair() 



Now that throttled tasks are dequeued and can not stay on rq's cfs_tasks
list, there is no need to take special care of these throttled tasks
anymore in load balance.

Suggested-by: default avatarK Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: default avatarAaron Lu <ziqianlu@bytedance.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarValentin Schneider <vschneid@redhat.com>
Tested-by: default avatarMatteo Martelli <matteo.martelli@codethink.co.uk>
Tested-by: default avatarK Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250829081120.806-6-ziqianlu@bytedance.com
parent eb962f25

kernel/sched/fair.c

+4 −31
Original line number Diff line number Diff line
@@ -5735,23 +5735,6 @@ static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) 
	return cfs_bandwidth_used() && cfs_rq->throttle_count;

}



/*

 * Ensure that neither of the group entities corresponding to src_cpu or

 * dest_cpu are members of a throttled hierarchy when performing group

 * load-balance operations.

 */

static inline int throttled_lb_pair(struct task_group *tg,

				    int src_cpu, int dest_cpu)

{

	struct cfs_rq *src_cfs_rq, *dest_cfs_rq;



	src_cfs_rq = tg->cfs_rq[src_cpu];

	dest_cfs_rq = tg->cfs_rq[dest_cpu];



	return throttled_hierarchy(src_cfs_rq) ||

	       throttled_hierarchy(dest_cfs_rq);

}



static inline bool task_is_throttled(struct task_struct *p)

{

	return cfs_bandwidth_used() && p->throttled;
@@ -6743,12 +6726,6 @@ static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) 
	return 0;

}



static inline int throttled_lb_pair(struct task_group *tg,

				    int src_cpu, int dest_cpu)

{

	return 0;

}



#ifdef CONFIG_FAIR_GROUP_SCHED

void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent) {}

static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
@@ -9385,18 +9362,14 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env) 
	/*

	 * We do not migrate tasks that are:

	 * 1) delayed dequeued unless we migrate load, or

	 * 2) throttled_lb_pair, or

	 * 3) cannot be migrated to this CPU due to cpus_ptr, or

	 * 4) running (obviously), or

	 * 5) are cache-hot on their current CPU, or

	 * 6) are blocked on mutexes (if SCHED_PROXY_EXEC is enabled)

	 * 2) cannot be migrated to this CPU due to cpus_ptr, or

	 * 3) running (obviously), or

	 * 4) are cache-hot on their current CPU, or

	 * 5) are blocked on mutexes (if SCHED_PROXY_EXEC is enabled)

	 */

	if ((p->se.sched_delayed) && (env->migration_type != migrate_load))

		return 0;



	if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))

		return 0;



	/*

	 * We want to prioritize the migration of eligible tasks.

	 * For ineligible tasks we soft-limit them and only allow