1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * Hierarchical Budget Worst-case Fair Weighted Fair Queueing
4  * (B-WF2Q+): hierarchical scheduling algorithm by which the BFQ I/O
9 #include "bfq-iosched.h"
12  * bfq_gt - compare two timestamps.
20 	return (s64)(a - b) > 0;  in bfq_gt()
25 	struct rb_node *node = tree->rb_node;  in bfq_root_active_entity()
34 	return bfqq ? bfqq->ioprio_class - 1 :  in bfq_class_idx()
35 		BFQ_DEFAULT_GRP_CLASS - 1;  in bfq_class_idx()
40 	return bfqd->busy_queues[0] + bfqd->busy_queues[1] +  in bfq_tot_busy_queues()
41 		bfqd->busy_queues[2];  in bfq_tot_busy_queues()
50  * bfq_update_next_in_service - update sd->next_in_service
56  *             expiration of the in-service entity
58  * This function is called to update sd->next_in_service, which, in
60  * extraction of an entity into/from one of the active trees of
65  * reposition an entity in its active tree; see comments on
67  * both the last two activation sub-cases, new_entity points to the
70  * Returns true if sd->next_in_service changes in such a way that
71  * entity->parent may become the next_in_service for its parent
78 	struct bfq_entity *next_in_service = sd->next_in_service;  in bfq_update_next_in_service()
85 	 * sd->next_in_service, then a full lookup in the active tree  in bfq_update_next_in_service()
87 	 * just-modified entity has the same priority as  in bfq_update_next_in_service()
88 	 * sd->next_in_service, is eligible and has a lower virtual  in bfq_update_next_in_service()
89 	 * finish time than sd->next_in_service. If this compound  in bfq_update_next_in_service()
93 	if (new_entity && new_entity != sd->next_in_service) {  in bfq_update_next_in_service()
96 		 * sd->next_in_service with new_entity. Tentatively  in bfq_update_next_in_service()
98 		 * sd->next_in_service is NULL.  in bfq_update_next_in_service()
105 		 * to replace sd->service_tree with new_entity.  in bfq_update_next_in_service()
111 				sd->service_tree + new_entity_class_idx;  in bfq_update_next_in_service()
117 				 !bfq_gt(new_entity->start, st->vtime)  in bfq_update_next_in_service()
119 				 bfq_gt(next_in_service->finish,  in bfq_update_next_in_service()
120 					new_entity->finish));  in bfq_update_next_in_service()
134 		parent_sched_may_change = !sd->next_in_service ||  in bfq_update_next_in_service()
138 	sd->next_in_service = next_in_service;  in bfq_update_next_in_service()
146  * Returns true if this budget changes may let next_in_service->parent
156 	group_sd = next_in_service->sched_data;  in bfq_update_parent_budget()
160 	 * bfq_group's my_entity field is not NULL only if the group  in bfq_update_parent_budget()
162 	 * as it must never become an in-service entity.  in bfq_update_parent_budget()
164 	bfqg_entity = bfqg->my_entity;  in bfq_update_parent_budget()
166 		if (bfqg_entity->budget > next_in_service->budget)  in bfq_update_parent_budget()
168 		bfqg_entity->budget = next_in_service->budget;  in bfq_update_parent_budget()
176  * service, according to the restrictive definition of the field
182  * about to become the in-service queue. This function then returns
186  * it is not a queue, and has more than one active child. In fact,
187  * even if one of its children is about to be set in service, other
188  * active children may still be the next to serve, for the parent
189  * entity, even according to the above definition. As a consequence, a
190  * non-queue entity is not a candidate for next-service only if it has
191  * only one active child. And only if this condition holds, then this
192  * function returns true for a non-queue entity.
204 	 * The field active_entities does not always contain the  in bfq_no_longer_next_in_service()
205 	 * actual number of active children entities: it happens to  in bfq_no_longer_next_in_service()
206 	 * not account for the in-service entity in case the latter is  in bfq_no_longer_next_in_service()
207 	 * removed from its active tree (which may get done after  in bfq_no_longer_next_in_service()
213 	 * actual number of active entities.  in bfq_no_longer_next_in_service()
215 	if (bfqg->active_entities == 1)  in bfq_no_longer_next_in_service()
248 	if (!entity->my_sched_data)  in bfq_entity_to_bfqq()
256  * bfq_delta - map service into the virtual time domain.
266  * bfq_calc_finish - assign the finish time to an entity.
274 	entity->finish = entity->start +  in bfq_calc_finish()
275 		bfq_delta(service, entity->weight);  in bfq_calc_finish()
278 		bfq_log_bfqq(bfqq->bfqd, bfqq,  in bfq_calc_finish()
280 			service, entity->weight);  in bfq_calc_finish()
281 		bfq_log_bfqq(bfqq->bfqd, bfqq,  in bfq_calc_finish()
283 			entity->start, entity->finish,  in bfq_calc_finish()
284 			bfq_delta(service, entity->weight));  in bfq_calc_finish()
289  * bfq_entity_of - get an entity from a node.
290  * @node: the node field of the entity.
308  * bfq_extract - remove an entity from a tree.
314 	entity->tree = NULL;  in bfq_extract()
315 	rb_erase(&entity->rb_node, root);  in bfq_extract()
319  * bfq_idle_extract - extract an entity from the idle tree.
329 	if (entity == st->first_idle) {  in bfq_idle_extract()
330 		next = rb_next(&entity->rb_node);  in bfq_idle_extract()
331 		st->first_idle = bfq_entity_of(next);  in bfq_idle_extract()
334 	if (entity == st->last_idle) {  in bfq_idle_extract()
335 		next = rb_prev(&entity->rb_node);  in bfq_idle_extract()
336 		st->last_idle = bfq_entity_of(next);  in bfq_idle_extract()
339 	bfq_extract(&st->idle, entity);  in bfq_idle_extract()
342 		list_del(&bfqq->bfqq_list);  in bfq_idle_extract()
346  * bfq_insert - generic tree insertion.
350  * This is used for the idle and the active tree, since they are both
356 	struct rb_node **node = &root->rb_node;  in bfq_insert()
363 		if (bfq_gt(entry->finish, entity->finish))  in bfq_insert()
364 			node = &parent->rb_left;  in bfq_insert()
366 			node = &parent->rb_right;  in bfq_insert()
369 	rb_link_node(&entity->rb_node, parent, node);  in bfq_insert()
370 	rb_insert_color(&entity->rb_node, root);  in bfq_insert()
372 	entity->tree = root;  in bfq_insert()
376  * bfq_update_min - update the min_start field of a entity.
381  * min_start due to updates to the active tree.  The function  assumes
391 		if (bfq_gt(entity->min_start, child->min_start))  in bfq_update_min()
392 			entity->min_start = child->min_start;  in bfq_update_min()
397  * bfq_update_active_node - recalculate min_start.
408 	entity->min_start = entity->start;  in bfq_update_active_node()
409 	bfq_update_min(entity, node->rb_right);  in bfq_update_active_node()
410 	bfq_update_min(entity, node->rb_left);  in bfq_update_active_node()
414  * bfq_update_active_tree - update min_start for the whole active tree.
434 	if (node == parent->rb_left && parent->rb_right)  in bfq_update_active_tree()
435 		bfq_update_active_node(parent->rb_right);  in bfq_update_active_tree()
436 	else if (parent->rb_left)  in bfq_update_active_tree()
437 		bfq_update_active_node(parent->rb_left);  in bfq_update_active_tree()
444  * bfq_active_insert - insert an entity in the active tree of its
449  * The active tree is ordered by finish time, but an extra key is kept
458 	struct rb_node *node = &entity->rb_node;  in bfq_active_insert()
465 	bfq_insert(&st->active, entity);  in bfq_active_insert()
467 	if (node->rb_left)  in bfq_active_insert()
468 		node = node->rb_left;  in bfq_active_insert()
469 	else if (node->rb_right)  in bfq_active_insert()
470 		node = node->rb_right;  in bfq_active_insert()
475 	sd = entity->sched_data;  in bfq_active_insert()
477 	bfqd = (struct bfq_data *)bfqg->bfqd;  in bfq_active_insert()
480 		list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);  in bfq_active_insert()
482 	if (bfqg != bfqd->root_group)  in bfq_active_insert()
483 		bfqg->active_entities++;  in bfq_active_insert()
488  * bfq_ioprio_to_weight - calc a weight from an ioprio.
493 	return (IOPRIO_NR_LEVELS - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;  in bfq_ioprio_to_weight()
497  * bfq_weight_to_ioprio - calc an ioprio from a weight.
500  * To preserve as much as possible the old only-ioprio user interface,
507 		     IOPRIO_NR_LEVELS - weight / BFQ_WEIGHT_CONVERSION_COEFF);  in bfq_weight_to_ioprio()
515 		bfqq->ref++;  in bfq_get_entity()
516 		bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",  in bfq_get_entity()
517 			     bfqq, bfqq->ref);  in bfq_get_entity()
522  * bfq_find_deepest - find the deepest node that an extraction can modify.
534 	if (!node->rb_right && !node->rb_left)  in bfq_find_deepest()
536 	else if (!node->rb_right)  in bfq_find_deepest()
537 		deepest = node->rb_left;  in bfq_find_deepest()
538 	else if (!node->rb_left)  in bfq_find_deepest()
539 		deepest = node->rb_right;  in bfq_find_deepest()
542 		if (deepest->rb_right)  in bfq_find_deepest()
543 			deepest = deepest->rb_right;  in bfq_find_deepest()
552  * bfq_active_extract - remove an entity from the active tree.
567 	node = bfq_find_deepest(&entity->rb_node);  in bfq_active_extract()
568 	bfq_extract(&st->active, entity);  in bfq_active_extract()
574 	sd = entity->sched_data;  in bfq_active_extract()
576 	bfqd = (struct bfq_data *)bfqg->bfqd;  in bfq_active_extract()
579 		list_del(&bfqq->bfqq_list);  in bfq_active_extract()
581 	if (bfqg != bfqd->root_group)  in bfq_active_extract()
582 		bfqg->active_entities--;  in bfq_active_extract()
587  * bfq_idle_insert - insert an entity into the idle tree.
595 	struct bfq_entity *first_idle = st->first_idle;  in bfq_idle_insert()
596 	struct bfq_entity *last_idle = st->last_idle;  in bfq_idle_insert()
598 	if (!first_idle || bfq_gt(first_idle->finish, entity->finish))  in bfq_idle_insert()
599 		st->first_idle = entity;  in bfq_idle_insert()
600 	if (!last_idle || bfq_gt(entity->finish, last_idle->finish))  in bfq_idle_insert()
601 		st->last_idle = entity;  in bfq_idle_insert()
603 	bfq_insert(&st->idle, entity);  in bfq_idle_insert()
606 		list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);  in bfq_idle_insert()
610  * bfq_forget_entity - do not consider entity any longer for scheduling
613  * @is_in_service: true if entity is currently the in-service entity.
630 	entity->on_st_or_in_serv = false;  in bfq_forget_entity()
631 	st->wsum -= entity->weight;  in bfq_forget_entity()
637  * bfq_put_idle_entity - release the idle tree ref of an entity.
645 			  entity == entity->sched_data->in_service_entity);  in bfq_put_idle_entity()
649  * bfq_forget_idle - update the idle tree if necessary.
657 	struct bfq_entity *first_idle = st->first_idle;  in bfq_forget_idle()
658 	struct bfq_entity *last_idle = st->last_idle;  in bfq_forget_idle()
660 	if (RB_EMPTY_ROOT(&st->active) && last_idle &&  in bfq_forget_idle()
661 	    !bfq_gt(last_idle->finish, st->vtime)) {  in bfq_forget_idle()
666 		st->vtime = last_idle->finish;  in bfq_forget_idle()
669 	if (first_idle && !bfq_gt(first_idle->finish, st->vtime))  in bfq_forget_idle()
675 	struct bfq_sched_data *sched_data = entity->sched_data;  in bfq_entity_service_tree()
678 	return sched_data->service_tree + idx;  in bfq_entity_service_tree()
706 	if (entity->prio_changed) {  in __bfq_entity_update_weight_prio()
717 			bfqd = bfqq->bfqd;  in __bfq_entity_update_weight_prio()
720 			sd = entity->my_sched_data;  in __bfq_entity_update_weight_prio()
722 			bfqd = (struct bfq_data *)bfqg->bfqd;  in __bfq_entity_update_weight_prio()
728 		old_st->wsum -= entity->weight;  in __bfq_entity_update_weight_prio()
730 		if (entity->new_weight != entity->orig_weight) {  in __bfq_entity_update_weight_prio()
731 			if (entity->new_weight < BFQ_MIN_WEIGHT ||  in __bfq_entity_update_weight_prio()
732 			    entity->new_weight > BFQ_MAX_WEIGHT) {  in __bfq_entity_update_weight_prio()
734 					entity->new_weight);  in __bfq_entity_update_weight_prio()
735 				if (entity->new_weight < BFQ_MIN_WEIGHT)  in __bfq_entity_update_weight_prio()
736 					entity->new_weight = BFQ_MIN_WEIGHT;  in __bfq_entity_update_weight_prio()
738 					entity->new_weight = BFQ_MAX_WEIGHT;  in __bfq_entity_update_weight_prio()
740 			entity->orig_weight = entity->new_weight;  in __bfq_entity_update_weight_prio()
742 				bfqq->ioprio =  in __bfq_entity_update_weight_prio()
743 				  bfq_weight_to_ioprio(entity->orig_weight);  in __bfq_entity_update_weight_prio()
747 			bfqq->ioprio_class = bfqq->new_ioprio_class;  in __bfq_entity_update_weight_prio()
753 		if (!bfqq || bfqq->ioprio_class == bfqq->new_ioprio_class)  in __bfq_entity_update_weight_prio()
754 			entity->prio_changed = 0;  in __bfq_entity_update_weight_prio()
761 		 * when entity->finish <= old_st->vtime).  in __bfq_entity_update_weight_prio()
765 		prev_weight = entity->weight;  in __bfq_entity_update_weight_prio()
766 		new_weight = entity->orig_weight *  in __bfq_entity_update_weight_prio()
767 			     (bfqq ? bfqq->wr_coeff : 1);  in __bfq_entity_update_weight_prio()
774 			root = &bfqd->queue_weights_tree;  in __bfq_entity_update_weight_prio()
777 		entity->weight = new_weight;  in __bfq_entity_update_weight_prio()
779 		 * Add the entity, if it is not a weight-raised queue,  in __bfq_entity_update_weight_prio()
782 		if (prev_weight != new_weight && bfqq && bfqq->wr_coeff == 1) {  in __bfq_entity_update_weight_prio()
787 		new_st->wsum += entity->weight;  in __bfq_entity_update_weight_prio()
790 			entity->start = new_st->vtime;  in __bfq_entity_update_weight_prio()
797  * bfq_bfqq_served - update the scheduler status after selection for
808 	struct bfq_entity *entity = &bfqq->entity;  in bfq_bfqq_served()
811 	if (!bfqq->service_from_backlogged)  in bfq_bfqq_served()
812 		bfqq->first_IO_time = jiffies;  in bfq_bfqq_served()
814 	if (bfqq->wr_coeff > 1)  in bfq_bfqq_served()
815 		bfqq->service_from_wr += served;  in bfq_bfqq_served()
817 	bfqq->service_from_backlogged += served;  in bfq_bfqq_served()
821 		entity->service += served;  in bfq_bfqq_served()
823 		st->vtime += bfq_delta(served, st->wsum);  in bfq_bfqq_served()
826 	bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served);  in bfq_bfqq_served()
830  * bfq_bfqq_charge_time - charge an amount of service equivalent to the length
841  * goal is achieved through the BFQ scheduling engine, even if such an
859 	struct bfq_entity *entity = &bfqq->entity;  in bfq_bfqq_charge_time()
863 		(bfqd->bfq_max_budget * bounded_time_ms) / timeout_ms;  in bfq_bfqq_charge_time()
864 	int tot_serv_to_charge = max(serv_to_charge_for_time, entity->service);  in bfq_bfqq_charge_time()
867 	if (tot_serv_to_charge > entity->budget)  in bfq_bfqq_charge_time()
868 		entity->budget = tot_serv_to_charge;  in bfq_bfqq_charge_time()
871 			max_t(int, 0, tot_serv_to_charge - entity->service));  in bfq_bfqq_charge_time()
886 	bfq_calc_finish(entity, entity->budget);  in bfq_update_fin_time_enqueue()
898 	 * idle, the system virtual time may be pushed-up to much  in bfq_update_fin_time_enqueue()
913 	 * worst-case fairness guarantees.  in bfq_update_fin_time_enqueue()
915 	 * As a special case, if bfqq is weight-raised, push up  in bfq_update_fin_time_enqueue()
918 	 * weight-raised queues to become higher than the backshifted  in bfq_update_fin_time_enqueue()
919 	 * finish timestamps of non weight-raised queues.  in bfq_update_fin_time_enqueue()
921 	if (backshifted && bfq_gt(st->vtime, entity->finish)) {  in bfq_update_fin_time_enqueue()
922 		unsigned long delta = st->vtime - entity->finish;  in bfq_update_fin_time_enqueue()
925 			delta /= bfqq->wr_coeff;  in bfq_update_fin_time_enqueue()
927 		entity->start += delta;  in bfq_update_fin_time_enqueue()
928 		entity->finish += delta;  in bfq_update_fin_time_enqueue()
935  * __bfq_activate_entity - handle activation of entity.
939  * Called for a 'true' activation, i.e., if entity is not active and
943  * inserts entity into its active tree, after possibly extracting it
954 	if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {  in __bfq_activate_entity()
956 		min_vstart = entity->finish;  in __bfq_activate_entity()
958 		min_vstart = st->vtime;  in __bfq_activate_entity()
960 	if (entity->tree == &st->idle) {  in __bfq_activate_entity()
966 		entity->start = bfq_gt(min_vstart, entity->finish) ?  in __bfq_activate_entity()
967 			min_vstart : entity->finish;  in __bfq_activate_entity()
974 		entity->start = min_vstart;  in __bfq_activate_entity()
975 		st->wsum += entity->weight;  in __bfq_activate_entity()
984 		entity->on_st_or_in_serv = true;  in __bfq_activate_entity()
991 		struct bfq_data *bfqd = bfqg->bfqd;  in __bfq_activate_entity()
993 		if (!entity->in_groups_with_pending_reqs) {  in __bfq_activate_entity()
994 			entity->in_groups_with_pending_reqs = true;  in __bfq_activate_entity()
995 			bfqd->num_groups_with_pending_reqs++;  in __bfq_activate_entity()
1004  * __bfq_requeue_entity - handle requeueing or repositioning of an entity.
1013  * Basically, this function: 1) removes entity from its active tree if
1015  * entity back into its active tree (in the new, right position for
1020 	struct bfq_sched_data *sd = entity->sched_data;  in __bfq_requeue_entity()
1023 	if (entity == sd->in_service_entity) {  in __bfq_requeue_entity()
1025 		 * We are requeueing the current in-service entity,  in __bfq_requeue_entity()
1028 		 * - entity represents the in-service queue, and the  in __bfq_requeue_entity()
1029 		 *   in-service queue is being requeued after an  in __bfq_requeue_entity()
1031 		 * - entity represents a group, and its budget has  in __bfq_requeue_entity()
1046 		bfq_calc_finish(entity, entity->service);  in __bfq_requeue_entity()
1047 		entity->start = entity->finish;  in __bfq_requeue_entity()
1051 		 * the active tree. This implies that the position of  in __bfq_requeue_entity()
1052 		 * the entity in the active tree may need to be  in __bfq_requeue_entity()
1061 		if (entity->tree)  in __bfq_requeue_entity()
1063 	} else { /* The entity is already active, and not in service */  in __bfq_requeue_entity()
1071 		 * i.e., the position in the active tree, of this  in __bfq_requeue_entity()
1076 		 * non-extracted-entity sub-case above.  in __bfq_requeue_entity()
1090 	if (sd->in_service_entity == entity || entity->tree == &st->active)  in __bfq_activate_requeue_entity()
1092 		  * in service or already queued on the active tree,  in __bfq_activate_requeue_entity()
1098 		 * Not in service and not queued on its active tree:  in __bfq_activate_requeue_entity()
1106  * bfq_activate_requeue_entity - activate or requeue an entity representing a
1116  *             of the in-service queue
1125 		sd = entity->sched_data;  in bfq_activate_requeue_entity()
1135  * __bfq_deactivate_entity - update sched_data and service trees for
1146 	struct bfq_sched_data *sd = entity->sched_data;  in __bfq_deactivate_entity()
1150 	if (!entity->on_st_or_in_serv) /*  in __bfq_deactivate_entity()
1157 	 * If we get here, then entity is active, which implies that  in __bfq_deactivate_entity()
1159 	 * represented by entity. Therefore, the field  in __bfq_deactivate_entity()
1160 	 * entity->sched_data has been set, and we can safely use it.  in __bfq_deactivate_entity()
1163 	is_in_service = entity == sd->in_service_entity;  in __bfq_deactivate_entity()
1165 	bfq_calc_finish(entity, entity->service);  in __bfq_deactivate_entity()
1168 		sd->in_service_entity = NULL;  in __bfq_deactivate_entity()
1171 		 * Non in-service entity: nobody will take care of  in __bfq_deactivate_entity()
1175 		entity->service = 0;  in __bfq_deactivate_entity()
1177 	if (entity->tree == &st->active)  in __bfq_deactivate_entity()
1179 	else if (!is_in_service && entity->tree == &st->idle)  in __bfq_deactivate_entity()
1182 	if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime))  in __bfq_deactivate_entity()
1191  * bfq_deactivate_entity - deactivate an entity representing a bfq_queue.
1195  *             of the in-service queue
1205 		sd = entity->sched_data;  in bfq_deactivate_entity()
1210 			 * this deactivation is a no-op, and there is  in bfq_deactivate_entity()
1211 			 * nothing to change for upper-level entities  in bfq_deactivate_entity()
1218 		if (sd->next_in_service == entity)  in bfq_deactivate_entity()
1226 		if (sd->next_in_service || sd->in_service_entity) {  in bfq_deactivate_entity()
1228 			 * The parent entity is still active, because  in bfq_deactivate_entity()
1238 			 * active. This happens if 1) the entity  in bfq_deactivate_entity()
1240 			 * active entity in the parent entity, and 2)  in bfq_deactivate_entity()
1275 		 * Invoke __bfq_requeue_entity on entity, even if  in bfq_deactivate_entity()
1276 		 * already active, to requeue/reposition it in the  in bfq_deactivate_entity()
1277 		 * active tree (because sd->next_in_service has  in bfq_deactivate_entity()
1282 		sd = entity->sched_data;  in bfq_deactivate_entity()
1287 			 * any change in entity->parent->sd, and no  in bfq_deactivate_entity()
1296  * bfq_calc_vtime_jump - compute the value to which the vtime should jump,
1304 	struct bfq_entity *root_entity = bfq_root_active_entity(&st->active);  in bfq_calc_vtime_jump()
1306 	if (bfq_gt(root_entity->min_start, st->vtime))  in bfq_calc_vtime_jump()
1307 		return root_entity->min_start;  in bfq_calc_vtime_jump()
1309 	return st->vtime;  in bfq_calc_vtime_jump()
1314 	if (new_value > st->vtime) {  in bfq_update_vtime()
1315 		st->vtime = new_value;  in bfq_update_vtime()
1321  * bfq_first_active_entity - find the eligible entity with
1336 	struct rb_node *node = st->active.rb_node;  in bfq_first_active_entity()
1341 		if (!bfq_gt(entry->start, vtime))  in bfq_first_active_entity()
1344 		if (node->rb_left) {  in bfq_first_active_entity()
1345 			entry = rb_entry(node->rb_left,  in bfq_first_active_entity()
1347 			if (!bfq_gt(entry->min_start, vtime)) {  in bfq_first_active_entity()
1348 				node = node->rb_left;  in bfq_first_active_entity()
1354 		node = node->rb_right;  in bfq_first_active_entity()
1361  * __bfq_lookup_next_entity - return the first eligible entity in @st.
1363  * @in_service: whether or not there is an in-service entity for the sched_data
1364  *	this active tree belongs to.
1366  * If there is no in-service entity for the sched_data st belongs to,
1376  * In contrast, if there is an in-service entity, then return the
1379  * in-service entity, on expiration,
1390 	if (RB_EMPTY_ROOT(&st->active))  in __bfq_lookup_next_entity()
1400 	 * If there is no in-service entity for the sched_data this  in __bfq_lookup_next_entity()
1401 	 * active tree belongs to, then push the system virtual time  in __bfq_lookup_next_entity()
1403 	 * eligible. If, instead, there is an in-service entity, then  in __bfq_lookup_next_entity()
1405 	 * eligible entity, namely the in-service one (even if the  in __bfq_lookup_next_entity()
1418  * bfq_lookup_next_entity - return the first eligible entity in @sd.
1420  * @expiration: true if we are on the expiration path of the in-service queue
1429 	struct bfq_service_tree *st = sd->service_tree;  in bfq_lookup_next_entity()
1430 	struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1);  in bfq_lookup_next_entity()
1436 	 * bandwidth to this class (and if there is some active entity  in bfq_lookup_next_entity()
1438 	 * priority-inversion problems in case a low priority task is  in bfq_lookup_next_entity()
1441 	if (time_is_before_jiffies(sd->bfq_class_idle_last_service +  in bfq_lookup_next_entity()
1443 		if (!RB_EMPTY_ROOT(&idle_class_st->active))  in bfq_lookup_next_entity()
1444 			class_idx = BFQ_IOPRIO_CLASSES - 1;  in bfq_lookup_next_entity()
1446 		sd->bfq_class_idle_last_service = jiffies;  in bfq_lookup_next_entity()
1450 	 * Find the next entity to serve for the highest-priority  in bfq_lookup_next_entity()
1457 		 * of the in-service queue. In this case, even if  in bfq_lookup_next_entity()
1458 		 * sd->in_service_entity is not NULL,  in bfq_lookup_next_entity()
1459 		 * sd->in_service_entity at this point is actually not  in bfq_lookup_next_entity()
1462 		 * tree. The reason why sd->in_service_entity is still  in bfq_lookup_next_entity()
1463 		 * not NULL here, even if expiration is true, is that  in bfq_lookup_next_entity()
1464 		 * sd->in_service_entity is reset as a last step in the  in bfq_lookup_next_entity()
1467 		 * sd->in_service_entity.  in bfq_lookup_next_entity()
1470 						  sd->in_service_entity &&  in bfq_lookup_next_entity()
1482 	struct bfq_sched_data *sd = &bfqd->root_group->sched_data;  in next_queue_may_preempt()
1484 	return sd->next_in_service != sd->in_service_entity;  in next_queue_may_preempt()
1504 	sd = &bfqd->root_group->sched_data;  in bfq_get_next_queue()
1505 	for (; sd ; sd = entity->my_sched_data) {  in bfq_get_next_queue()
1507 		 * WARNING. We are about to set the in-service entity  in bfq_get_next_queue()
1508 		 * to sd->next_in_service, i.e., to the (cached) value  in bfq_get_next_queue()
1516 		 * pointed to by sd->next_in_service. This rare event  in bfq_get_next_queue()
1524 		 * service of the sd->next_in_service entity  in bfq_get_next_queue()
1527 		 * exactly to update sd->next_in_service.  in bfq_get_next_queue()
1531 		entity = sd->next_in_service;  in bfq_get_next_queue()
1532 		sd->in_service_entity = entity;  in bfq_get_next_queue()
1536 		 * service, then it must be extracted from its active  in bfq_get_next_queue()
1547 		 * Even if entity is not to be extracted according to  in bfq_get_next_queue()
1557 		 * the correct next-to-serve candidate entity for each  in bfq_get_next_queue()
1560 		 * the next-to-serve leaf entity, we can discover  in bfq_get_next_queue()
1562 		 * becomes the next-to-serve, and so on.  in bfq_get_next_queue()
1569 	 * We can finally update all next-to-serve entities along the  in bfq_get_next_queue()
1573 		struct bfq_sched_data *sd = entity->sched_data;  in bfq_get_next_queue()
1582 /* returns true if the in-service queue gets freed */
1585 	struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue;  in __bfq_bfqd_reset_in_service()
1586 	struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity;  in __bfq_bfqd_reset_in_service()
1590 	hrtimer_try_to_cancel(&bfqd->idle_slice_timer);  in __bfq_bfqd_reset_in_service()
1591 	bfqd->in_service_queue = NULL;  in __bfq_bfqd_reset_in_service()
1594 	 * When this function is called, all in-service entities have  in __bfq_bfqd_reset_in_service()
1600 		entity->sched_data->in_service_entity = NULL;  in __bfq_bfqd_reset_in_service()
1607 	if (!in_serv_entity->on_st_or_in_serv) {  in __bfq_bfqd_reset_in_service()
1614 		int ref = in_serv_bfqq->ref;  in __bfq_bfqd_reset_in_service()
1626 	struct bfq_entity *entity = &bfqq->entity;  in bfq_deactivate_bfqq()
1633 	struct bfq_entity *entity = &bfqq->entity;  in bfq_activate_bfqq()
1643 	struct bfq_entity *entity = &bfqq->entity;  in bfq_requeue_bfqq()
1646 				    bfqq == bfqd->in_service_queue, expiration);  in bfq_requeue_bfqq()
1656 	struct bfq_data *bfqd = bfqq->bfqd;  in bfq_del_bfqq_busy()
1662 	bfqd->busy_queues[bfqq->ioprio_class - 1]--;  in bfq_del_bfqq_busy()
1664 	if (bfqq->wr_coeff > 1)  in bfq_del_bfqq_busy()
1665 		bfqd->wr_busy_queues--;  in bfq_del_bfqq_busy()
1671 	if (!bfqq->dispatched)  in bfq_del_bfqq_busy()
1680 	struct bfq_data *bfqd = bfqq->bfqd;  in bfq_add_bfqq_busy()
1687 	bfqd->busy_queues[bfqq->ioprio_class - 1]++;  in bfq_add_bfqq_busy()
1689 	if (!bfqq->dispatched)  in bfq_add_bfqq_busy()
1690 		if (bfqq->wr_coeff == 1)  in bfq_add_bfqq_busy()
1692 					     &bfqd->queue_weights_tree);  in bfq_add_bfqq_busy()
1694 	if (bfqq->wr_coeff > 1)  in bfq_add_bfqq_busy()
1695 		bfqd->wr_busy_queues++;  in bfq_add_bfqq_busy()
1698 	if (!hlist_unhashed(&bfqq->woken_list_node) &&  in bfq_add_bfqq_busy()
1699 	    &bfqq->woken_list_node != bfqq->waker_bfqq->woken_list.first) {  in bfq_add_bfqq_busy()
1700 		hlist_del_init(&bfqq->woken_list_node);  in bfq_add_bfqq_busy()
1701 		hlist_add_head(&bfqq->woken_list_node,  in bfq_add_bfqq_busy()
1702 			       &bfqq->waker_bfqq->woken_list);  in bfq_add_bfqq_busy()