diff options
Diffstat (limited to 'block/bfq-iosched.c')
| -rw-r--r-- | block/bfq-iosched.c | 1083 |
1 files changed, 637 insertions, 446 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 71b51c1b4..05944cbaa 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -82,6 +82,9 @@ static const int bfq_back_penalty = 2; /* Idling period duration, in jiffies. */ static int bfq_slice_idle = HZ / 125; +/* Minimum number of assigned budgets for which stats are safe to compute. */ +static const int bfq_stats_min_budgets = 194; + /* Default maximum budget values, in sectors and number of requests. */ static const int bfq_default_max_budget = 16 * 1024; static const int bfq_max_budget_async_rq = 4; @@ -163,38 +166,22 @@ static int device_speed_thresh[2]; #define RQ_BIC(rq) ((struct bfq_io_cq *) (rq)->elv.priv[0]) #define RQ_BFQQ(rq) ((rq)->elv.priv[1]) -static inline void bfq_schedule_dispatch(struct bfq_data *bfqd); +static void bfq_schedule_dispatch(struct bfq_data *bfqd); #include "bfq-ioc.c" #include "bfq-sched.c" #include "bfq-cgroup.c" -#define bfq_class_idle(bfqq) ((bfqq)->entity.ioprio_class ==\ - IOPRIO_CLASS_IDLE) -#define bfq_class_rt(bfqq) ((bfqq)->entity.ioprio_class ==\ - IOPRIO_CLASS_RT) +#define bfq_class_idle(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE) +#define bfq_class_rt(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_RT) #define bfq_sample_valid(samples) ((samples) > 80) /* - * The following macro groups conditions that need to be evaluated when - * checking if existing queues and groups form a symmetric scenario - * and therefore idling can be reduced or disabled for some of the - * queues. See the comment to the function bfq_bfqq_must_not_expire() - * for further details. - */ -#ifdef CONFIG_CGROUP_BFQIO -#define symmetric_scenario (!bfqd->active_numerous_groups && \ - !bfq_differentiated_weights(bfqd)) -#else -#define symmetric_scenario (!bfq_differentiated_weights(bfqd)) -#endif - -/* * We regard a request as SYNC, if either it's a read or has the SYNC bit * set (in which case it could also be a direct WRITE). */ -static inline int bfq_bio_sync(struct bio *bio) +static int bfq_bio_sync(struct bio *bio) { if (bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC)) return 1; @@ -206,7 +193,7 @@ static inline int bfq_bio_sync(struct bio *bio) * Scheduler run of queue, if there are requests pending and no one in the * driver that will restart queueing. */ -static inline void bfq_schedule_dispatch(struct bfq_data *bfqd) +static void bfq_schedule_dispatch(struct bfq_data *bfqd) { if (bfqd->queued != 0) { bfq_log(bfqd, "schedule dispatch"); @@ -230,9 +217,9 @@ static struct request *bfq_choose_req(struct bfq_data *bfqd, #define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */ unsigned wrap = 0; /* bit mask: requests behind the disk head? */ - if (rq1 == NULL || rq1 == rq2) + if (!rq1 || rq1 == rq2) return rq2; - if (rq2 == NULL) + if (!rq2) return rq1; if (rq_is_sync(rq1) && !rq_is_sync(rq2)) @@ -345,17 +332,17 @@ bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root, bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d", (long long unsigned)sector, - bfqq != NULL ? bfqq->pid : 0); + bfqq ? bfqq->pid : 0); return bfqq; } -static void bfq_rq_pos_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq) +static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) { struct rb_node **p, *parent; struct bfq_queue *__bfqq; - if (bfqq->pos_root != NULL) { + if (bfqq->pos_root) { rb_erase(&bfqq->pos_node, bfqq->pos_root); bfqq->pos_root = NULL; } @@ -365,10 +352,10 @@ static void bfq_rq_pos_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq) if (!bfqq->next_rq) return; - bfqq->pos_root = &bfqd->rq_pos_tree; + bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree; __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root, blk_rq_pos(bfqq->next_rq), &parent, &p); - if (__bfqq == NULL) { + if (!__bfqq) { rb_link_node(&bfqq->pos_node, parent, p); rb_insert_color(&bfqq->pos_node, bfqq->pos_root); } else @@ -378,7 +365,7 @@ static void bfq_rq_pos_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq) /* * Tell whether there are active queues or groups with differentiated weights. */ -static inline bool bfq_differentiated_weights(struct bfq_data *bfqd) +static bool bfq_differentiated_weights(struct bfq_data *bfqd) { /* * For weights to differ, at least one of the trees must contain @@ -387,7 +374,7 @@ static inline bool bfq_differentiated_weights(struct bfq_data *bfqd) return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) && (bfqd->queue_weights_tree.rb_node->rb_left || bfqd->queue_weights_tree.rb_node->rb_right) -#ifdef CONFIG_CGROUP_BFQIO +#ifdef CONFIG_BFQ_GROUP_IOSCHED ) || (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) && (bfqd->group_weights_tree.rb_node->rb_left || @@ -397,6 +384,40 @@ static inline bool bfq_differentiated_weights(struct bfq_data *bfqd) } /* + * The following function returns true if every queue must receive the + * same share of the throughput (this condition is used when deciding + * whether idling may be disabled, see the comments in the function + * bfq_bfqq_may_idle()). + * + * Such a scenario occurs when: + * 1) all active queues have the same weight, + * 2) all active groups at the same level in the groups tree have the same + * weight, + * 3) all active groups at the same level in the groups tree have the same + * number of children. + * + * Unfortunately, keeping the necessary state for evaluating exactly the + * above symmetry conditions would be quite complex and time-consuming. + * Therefore this function evaluates, instead, the following stronger + * sub-conditions, for which it is much easier to maintain the needed + * state: + * 1) all active queues have the same weight, + * 2) all active groups have the same weight, + * 3) all active groups have at most one active child each. + * In particular, the last two conditions are always true if hierarchical + * support and the cgroups interface are not enabled, thus no state needs + * to be maintained in this case. + */ +static bool bfq_symmetric_scenario(struct bfq_data *bfqd) +{ + return +#ifdef CONFIG_BFQ_GROUP_IOSCHED + !bfqd->active_numerous_groups && +#endif + !bfq_differentiated_weights(bfqd); +} + +/* * If the weight-counter tree passed as input contains no counter for * the weight of the input entity, then add that counter; otherwise just * increment the existing counter. @@ -495,10 +516,10 @@ static struct request *bfq_find_next_rq(struct bfq_data *bfqd, BUG_ON(RB_EMPTY_NODE(&last->rb_node)); - if (rbprev != NULL) + if (rbprev) prev = rb_entry_rq(rbprev); - if (rbnext != NULL) + if (rbnext) next = rb_entry_rq(rbnext); else { rbnext = rb_first(&bfqq->sort_list); @@ -510,8 +531,8 @@ static struct request *bfq_find_next_rq(struct bfq_data *bfqd, } /* see the definition of bfq_async_charge_factor for details */ -static inline unsigned long bfq_serv_to_charge(struct request *rq, - struct bfq_queue *bfqq) +static unsigned long bfq_serv_to_charge(struct request *rq, + struct bfq_queue *bfqq) { return blk_rq_sectors(rq) * (1 + ((!bfq_bfqq_sync(bfqq)) * (bfqq->wr_coeff == 1) * @@ -537,7 +558,7 @@ static void bfq_updated_next_req(struct bfq_data *bfqd, struct request *next_rq = bfqq->next_rq; unsigned long new_budget; - if (next_rq == NULL) + if (!next_rq) return; if (bfqq == bfqd->in_service_queue) @@ -560,7 +581,7 @@ static void bfq_updated_next_req(struct bfq_data *bfqd, } } -static inline unsigned int bfq_wr_duration(struct bfq_data *bfqd) +static unsigned int bfq_wr_duration(struct bfq_data *bfqd) { u64 dur; @@ -573,13 +594,12 @@ static inline unsigned int bfq_wr_duration(struct bfq_data *bfqd) return dur; } -static inline unsigned -bfq_bfqq_cooperations(struct bfq_queue *bfqq) +static unsigned bfq_bfqq_cooperations(struct bfq_queue *bfqq) { return bfqq->bic ? bfqq->bic->cooperations : 0; } -static inline void +static void bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic) { if (bic->saved_idle_window) @@ -603,7 +623,7 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic) bfqq->wr_coeff = bfqq->bfqd->bfq_wr_coeff; bfqq->wr_cur_max_time = bic->wr_time_left; bfqq->last_wr_start_finish = jiffies; - bfqq->entity.ioprio_changed = 1; + bfqq->entity.prio_changed = 1; } /* * Clear wr_time_left to prevent bfq_bfqq_save_state() from @@ -613,11 +633,12 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic) bic->wr_time_left = 0; } -/* Must be called with the queue_lock held. */ static int bfqq_process_refs(struct bfq_queue *bfqq) { int process_refs, io_refs; + lockdep_assert_held(bfqq->bfqd->queue->queue_lock); + io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE]; process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st; BUG_ON(process_refs < 0); @@ -625,8 +646,7 @@ static int bfqq_process_refs(struct bfq_queue *bfqq) } /* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */ -static inline void bfq_reset_burst_list(struct bfq_data *bfqd, - struct bfq_queue *bfqq) +static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq) { struct bfq_queue *item; struct hlist_node *n; @@ -858,14 +878,14 @@ static void bfq_add_request(struct request *rq) */ prev = bfqq->next_rq; next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position); - BUG_ON(next_rq == NULL); + BUG_ON(!next_rq); bfqq->next_rq = next_rq; /* * Adjust priority tree position, if next_rq changes. */ if (prev != bfqq->next_rq) - bfq_rq_pos_tree_add(bfqd, bfqq); + bfq_pos_tree_add_move(bfqd, bfqq); if (!bfq_bfqq_busy(bfqq)) { bool soft_rt, coop_or_in_burst, @@ -873,6 +893,10 @@ static void bfq_add_request(struct request *rq) bfqq->budget_timeout + bfqd->bfq_wr_min_idle_time); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, + rq->cmd_flags); +#endif if (bfq_bfqq_sync(bfqq)) { bool already_in_burst = !hlist_unhashed(&bfqq->burst_list_node) || @@ -917,7 +941,7 @@ static void bfq_add_request(struct request *rq) goto add_bfqq_busy; if (bfq_bfqq_just_split(bfqq)) - goto set_ioprio_changed; + goto set_prio_changed; /* * If the queue: @@ -929,7 +953,7 @@ static void bfq_add_request(struct request *rq) * start a weight-raising period. */ if (old_wr_coeff == 1 && (interactive || soft_rt) && - (!bfq_bfqq_sync(bfqq) || bfqq->bic != NULL)) { + (!bfq_bfqq_sync(bfqq) || bfqq->bic)) { bfqq->wr_coeff = bfqd->bfq_wr_coeff; if (interactive) bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); @@ -1008,9 +1032,9 @@ static void bfq_add_request(struct request *rq) bfqd->bfq_wr_rt_max_time; } } -set_ioprio_changed: +set_prio_changed: if (old_wr_coeff != bfqq->wr_coeff) - entity->ioprio_changed = 1; + entity->prio_changed = 1; add_bfqq_busy: bfqq->last_idle_bklogged = jiffies; bfqq->service_from_backlogged = 0; @@ -1025,7 +1049,7 @@ add_bfqq_busy: bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); bfqd->wr_busy_queues++; - entity->ioprio_changed = 1; + entity->prio_changed = 1; bfq_log_bfqq(bfqd, bfqq, "non-idle wrais starting at %lu, rais_max_time %u", jiffies, @@ -1048,11 +1072,11 @@ static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd, struct bfq_queue *bfqq; bic = bfq_bic_lookup(bfqd, tsk->io_context); - if (bic == NULL) + if (!bic) return NULL; bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio)); - if (bfqq != NULL) + if (bfqq) return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio)); return NULL; @@ -1068,8 +1092,7 @@ static void bfq_activate_request(struct request_queue *q, struct request *rq) (long long unsigned)bfqd->last_position); } -static inline void bfq_deactivate_request(struct request_queue *q, - struct request *rq) +static void bfq_deactivate_request(struct request_queue *q, struct request *rq) { struct bfq_data *bfqd = q->elevator->elevator_data; @@ -1101,7 +1124,7 @@ static void bfq_remove_request(struct request *rq) /* * Remove queue from request-position tree as it is empty. */ - if (bfqq->pos_root != NULL) { + if (bfqq->pos_root) { rb_erase(&bfqq->pos_node, bfqq->pos_root); bfqq->pos_root = NULL; } @@ -1111,6 +1134,9 @@ static void bfq_remove_request(struct request *rq) BUG_ON(bfqq->meta_pending == 0); bfqq->meta_pending--; } +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags); +#endif } static int bfq_merge(struct request_queue *q, struct request **req, @@ -1120,7 +1146,7 @@ static int bfq_merge(struct request_queue *q, struct request **req, struct request *__rq; __rq = bfq_find_rq_fmerge(bfqd, bio); - if (__rq != NULL && elv_rq_merge_ok(__rq, bio)) { + if (__rq && elv_rq_merge_ok(__rq, bio)) { *req = __rq; return ELEVATOR_FRONT_MERGE; } @@ -1147,7 +1173,7 @@ static void bfq_merged_request(struct request_queue *q, struct request *req, prev = bfqq->next_rq; next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req, bfqd->last_position); - BUG_ON(next_rq == NULL); + BUG_ON(!next_rq); bfqq->next_rq = next_rq; /* * If next_rq changes, update both the queue's budget to @@ -1156,11 +1182,19 @@ static void bfq_merged_request(struct request_queue *q, struct request *req, */ if (prev != bfqq->next_rq) { bfq_updated_next_req(bfqd, bfqq); - bfq_rq_pos_tree_add(bfqd, bfqq); + bfq_pos_tree_add_move(bfqd, bfqq); } } } +#ifdef CONFIG_BFQ_GROUP_IOSCHED +static void bfq_bio_merged(struct request_queue *q, struct request *req, + struct bio *bio) +{ + bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_rw); +} +#endif + static void bfq_merged_requests(struct request_queue *q, struct request *rq, struct request *next) { @@ -1187,18 +1221,21 @@ static void bfq_merged_requests(struct request_queue *q, struct request *rq, bfqq->next_rq = rq; bfq_remove_request(next); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags); +#endif } /* Must be called with bfqq != NULL */ -static inline void bfq_bfqq_end_wr(struct bfq_queue *bfqq) +static void bfq_bfqq_end_wr(struct bfq_queue *bfqq) { - BUG_ON(bfqq == NULL); + BUG_ON(!bfqq); if (bfq_bfqq_busy(bfqq)) bfqq->bfqd->wr_busy_queues--; bfqq->wr_coeff = 1; bfqq->wr_cur_max_time = 0; /* Trigger a weight change on the next activation of the queue */ - bfqq->entity.ioprio_changed = 1; + bfqq->entity.prio_changed = 1; } static void bfq_end_wr_async_queues(struct bfq_data *bfqd, @@ -1208,9 +1245,9 @@ static void bfq_end_wr_async_queues(struct bfq_data *bfqd, for (i = 0; i < 2; i++) for (j = 0; j < IOPRIO_BE_NR; j++) - if (bfqg->async_bfqq[i][j] != NULL) + if (bfqg->async_bfqq[i][j]) bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]); - if (bfqg->async_idle_bfqq != NULL) + if (bfqg->async_idle_bfqq) bfq_bfqq_end_wr(bfqg->async_idle_bfqq); } @@ -1229,7 +1266,7 @@ static void bfq_end_wr(struct bfq_data *bfqd) spin_unlock_irq(bfqd->queue->queue_lock); } -static inline sector_t bfq_io_struct_pos(void *io_struct, bool request) +static sector_t bfq_io_struct_pos(void *io_struct, bool request) { if (request) return blk_rq_pos(io_struct); @@ -1237,25 +1274,18 @@ static inline sector_t bfq_io_struct_pos(void *io_struct, bool request) return ((struct bio *)io_struct)->bi_iter.bi_sector; } -static inline sector_t bfq_dist_from(sector_t pos1, - sector_t pos2) -{ - if (pos1 >= pos2) - return pos1 - pos2; - else - return pos2 - pos1; -} - -static inline int bfq_rq_close_to_sector(void *io_struct, bool request, - sector_t sector) +static int bfq_rq_close_to_sector(void *io_struct, bool request, + sector_t sector) { - return bfq_dist_from(bfq_io_struct_pos(io_struct, request), sector) <= + return abs64(bfq_io_struct_pos(io_struct, request) - sector) <= BFQQ_SEEK_THR; } -static struct bfq_queue *bfqq_close(struct bfq_data *bfqd, sector_t sector) +static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd, + struct bfq_queue *bfqq, + sector_t sector) { - struct rb_root *root = &bfqd->rq_pos_tree; + struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree; struct rb_node *parent, *node; struct bfq_queue *__bfqq; @@ -1267,7 +1297,7 @@ static struct bfq_queue *bfqq_close(struct bfq_data *bfqd, sector_t sector) * request, choose it. */ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL); - if (__bfqq != NULL) + if (__bfqq) return __bfqq; /* @@ -1283,7 +1313,7 @@ static struct bfq_queue *bfqq_close(struct bfq_data *bfqd, sector_t sector) node = rb_next(&__bfqq->pos_node); else node = rb_prev(&__bfqq->pos_node); - if (node == NULL) + if (!node) return NULL; __bfqq = rb_entry(node, struct bfq_queue, pos_node); @@ -1293,56 +1323,19 @@ static struct bfq_queue *bfqq_close(struct bfq_data *bfqd, sector_t sector) return NULL; } -/* - * bfqd - obvious - * cur_bfqq - passed in so that we don't decide that the current queue - * is closely cooperating with itself - * sector - used as a reference point to search for a close queue - */ -static struct bfq_queue *bfq_close_cooperator(struct bfq_data *bfqd, - struct bfq_queue *cur_bfqq, - sector_t sector) +static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd, + struct bfq_queue *cur_bfqq, + sector_t sector) { struct bfq_queue *bfqq; - if (bfq_class_idle(cur_bfqq)) - return NULL; - if (!bfq_bfqq_sync(cur_bfqq)) - return NULL; - if (BFQQ_SEEKY(cur_bfqq)) - return NULL; - - /* If device has only one backlogged bfq_queue, don't search. */ - if (bfqd->busy_queues == 1) - return NULL; - /* * We should notice if some of the queues are cooperating, e.g. * working closely on the same area of the disk. In that case, * we can group them together and don't waste time idling. */ - bfqq = bfqq_close(bfqd, sector); - if (bfqq == NULL || bfqq == cur_bfqq) - return NULL; - - /* - * Do not merge queues from different bfq_groups. - */ - if (bfqq->entity.parent != cur_bfqq->entity.parent) - return NULL; - - /* - * It only makes sense to merge sync queues. - */ - if (!bfq_bfqq_sync(bfqq)) - return NULL; - if (BFQQ_SEEKY(bfqq)) - return NULL; - - /* - * Do not merge queues of different priority classes. - */ - if (bfq_class_rt(bfqq) != bfq_class_rt(cur_bfqq)) + bfqq = bfqq_find_close(bfqd, cur_bfqq, sector); + if (!bfqq || bfqq == cur_bfqq) return NULL; return bfqq; @@ -1409,6 +1402,35 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) return new_bfqq; } +static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq, + struct bfq_queue *new_bfqq) +{ + if (WARN_ON(bfqq->entity.parent != new_bfqq->entity.parent)) + return false; + + if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) || + (bfqq->ioprio_class != new_bfqq->ioprio_class)) + return false; + + /* + * If either of the queues has already been detected as seeky, + * then merging it with the other queue is unlikely to lead to + * sequential I/O. + */ + if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq)) + return false; + + /* + * Interleaved I/O is known to be done by (some) applications + * only for reads, so it does not make sense to merge async + * queues. + */ + if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq)) + return false; + + return true; +} + /* * Attempt to schedule a merge of bfqq with the currently in-service queue * or with a close queue among the scheduled queues. @@ -1430,56 +1452,48 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, if (bfqq->new_bfqq) return bfqq->new_bfqq; - if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) return NULL; + /* If device has only one backlogged bfq_queue, don't search. */ + if (bfqd->busy_queues == 1) + return NULL; in_service_bfqq = bfqd->in_service_queue; - if (in_service_bfqq == NULL || in_service_bfqq == bfqq || + if (!in_service_bfqq || in_service_bfqq == bfqq || !bfqd->in_service_bic || unlikely(in_service_bfqq == &bfqd->oom_bfqq)) goto check_scheduled; - if (bfq_class_idle(in_service_bfqq) || bfq_class_idle(bfqq)) - goto check_scheduled; - - if (bfq_class_rt(in_service_bfqq) != bfq_class_rt(bfqq)) - goto check_scheduled; - - if (in_service_bfqq->entity.parent != bfqq->entity.parent) - goto check_scheduled; - if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) && - bfq_bfqq_sync(in_service_bfqq) && bfq_bfqq_sync(bfqq)) { + bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) { new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq); - if (new_bfqq != NULL) - return new_bfqq; /* Merge with in-service queue */ + if (new_bfqq) + return new_bfqq; } - /* * Check whether there is a cooperator among currently scheduled * queues. The only thing we need is that the bio/request is not * NULL, as we need it to establish whether a cooperator exists. */ check_scheduled: - new_bfqq = bfq_close_cooperator(bfqd, bfqq, - bfq_io_struct_pos(io_struct, request)); - if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq)) + new_bfqq = bfq_find_close_cooperator(bfqd, bfqq, + bfq_io_struct_pos(io_struct, request)); + if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) && + bfq_may_be_close_cooperator(bfqq, new_bfqq)) return bfq_setup_merge(bfqq, new_bfqq); return NULL; } -static inline void -bfq_bfqq_save_state(struct bfq_queue *bfqq) +static void bfq_bfqq_save_state(struct bfq_queue *bfqq) { /* - * If bfqq->bic == NULL, the queue is already shared or its requests + * If !bfqq->bic, the queue is already shared or its requests * have already been redirected to a shared queue; both idle window * and weight raising state have already been saved. Do nothing. */ - if (bfqq->bic == NULL) + if (!bfqq->bic) return; if (bfqq->bic->wr_time_left) /* @@ -1523,8 +1537,7 @@ bfq_bfqq_save_state(struct bfq_queue *bfqq) bfqq->bic->failed_cooperations = 0; } -static inline void -bfq_get_bic_reference(struct bfq_queue *bfqq) +static void bfq_get_bic_reference(struct bfq_queue *bfqq) { /* * If bfqq->bic has a non-NULL value, the bic to which it belongs @@ -1572,7 +1585,7 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, bfq_put_queue(bfqq); } -static inline void bfq_bfqq_increase_failed_cooperations(struct bfq_queue *bfqq) +static void bfq_bfqq_increase_failed_cooperations(struct bfq_queue *bfqq) { struct bfq_io_cq *bic = bfqq->bic; struct bfq_data *bfqd = bfqq->bfqd; @@ -1603,7 +1616,7 @@ static int bfq_allow_merge(struct request_queue *q, struct request *rq, * Queue lock is held here. */ bic = bfq_bic_lookup(bfqd, current->io_context); - if (bic == NULL) + if (!bic) return 0; bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio)); @@ -1611,9 +1624,9 @@ static int bfq_allow_merge(struct request_queue *q, struct request *rq, * We take advantage of this function to perform an early merge * of the queues of possible cooperating processes. */ - if (bfqq != NULL) { + if (bfqq) { new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false); - if (new_bfqq != NULL) { + if (new_bfqq) { bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq); /* * If we get here, the bio will be queued in the @@ -1631,7 +1644,10 @@ static int bfq_allow_merge(struct request_queue *q, struct request *rq, static void __bfq_set_in_service_queue(struct bfq_data *bfqd, struct bfq_queue *bfqq) { - if (bfqq != NULL) { + if (bfqq) { +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_avg_queue_size(bfqq_group(bfqq)); +#endif bfq_mark_bfqq_must_alloc(bfqq); bfq_mark_bfqq_budget_new(bfqq); bfq_clear_bfqq_fifo_expire(bfqq); @@ -1639,7 +1655,7 @@ static void __bfq_set_in_service_queue(struct bfq_data *bfqd, bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8; bfq_log_bfqq(bfqd, bfqq, - "set_in_service_queue, cur-budget = %lu", + "set_in_service_queue, cur-budget = %d", bfqq->entity.budget); } @@ -1662,9 +1678,9 @@ static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd) * stored in bfqd, which is dynamically updated according to the * estimated disk peak rate; otherwise return the default max budget */ -static inline unsigned long bfq_max_budget(struct bfq_data *bfqd) +static int bfq_max_budget(struct bfq_data *bfqd) { - if (bfqd->budgets_assigned < 194) + if (bfqd->budgets_assigned < bfq_stats_min_budgets) return bfq_default_max_budget; else return bfqd->bfq_max_budget; @@ -1674,9 +1690,9 @@ static inline unsigned long bfq_max_budget(struct bfq_data *bfqd) * Return min budget, which is a fraction of the current or default * max budget (trying with 1/32) */ -static inline unsigned long bfq_min_budget(struct bfq_data *bfqd) +static int bfq_min_budget(struct bfq_data *bfqd) { - if (bfqd->budgets_assigned < 194) + if (bfqd->budgets_assigned < bfq_stats_min_budgets) return bfq_default_max_budget / 32; else return bfqd->bfq_max_budget / 32; @@ -1692,7 +1708,7 @@ static void bfq_arm_slice_timer(struct bfq_data *bfqd) /* Processes have exited, don't wait. */ bic = bfqd->in_service_bic; - if (bic == NULL || atomic_read(&bic->icq.ioc->active_ref) == 0) + if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0) return; bfq_mark_bfqq_wait_request(bfqq); @@ -1718,12 +1734,15 @@ static void bfq_arm_slice_timer(struct bfq_data *bfqd) ((BFQQ_SEEKY(bfqq) && bfqq->entity.service > bfq_max_budget(bfqq->bfqd) / 8) || bfq_bfqq_constantly_seeky(bfqq)) && bfqq->wr_coeff == 1 && - symmetric_scenario) + bfq_symmetric_scenario(bfqd)) sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT)); else if (bfqq->wr_coeff > 1) sl = sl * 3; bfqd->last_idling_start = ktime_get(); mod_timer(&bfqd->idle_slice_timer, jiffies + sl); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_set_start_idle_time(bfqq_group(bfqq)); +#endif bfq_log(bfqd, "arm idle: %u/%u ms", jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle)); } @@ -1777,6 +1796,10 @@ static void bfq_dispatch_insert(struct request_queue *q, struct request *rq) if (bfq_bfqq_sync(bfqq)) bfqd->sync_flight++; +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_dispatch(bfqq_group(bfqq), blk_rq_bytes(rq), + rq->cmd_flags); +#endif } /* @@ -1802,7 +1825,7 @@ static struct request *bfq_check_fifo(struct bfq_queue *bfqq) return rq; } -static inline unsigned long bfq_bfqq_budget_left(struct bfq_queue *bfqq) +static int bfq_bfqq_budget_left(struct bfq_queue *bfqq) { struct bfq_entity *entity = &bfqq->entity; return entity->budget - entity->service; @@ -1836,7 +1859,7 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) /* * Resort priority tree of potential close cooperators. */ - bfq_rq_pos_tree_add(bfqd, bfqq); + bfq_pos_tree_add_move(bfqd, bfqq); } } @@ -1846,24 +1869,24 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) * @bfqq: queue to update. * @reason: reason for expiration. * - * Handle the feedback on @bfqq budget. See the body for detailed - * comments. + * Handle the feedback on @bfqq budget at queue expiration. + * See the body for detailed comments. */ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, struct bfq_queue *bfqq, enum bfqq_expiration reason) { struct request *next_rq; - unsigned long budget, min_budget; + int budget, min_budget; budget = bfqq->max_budget; min_budget = bfq_min_budget(bfqd); BUG_ON(bfqq != bfqd->in_service_queue); - bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %lu, budg left %lu", + bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d", bfqq->entity.budget, bfq_bfqq_budget_left(bfqq)); - bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %lu, min budg %lu", + bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d", budget, bfq_min_budget(bfqd)); bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d", bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue)); @@ -1940,18 +1963,19 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, default: return; } - } else /* async queue */ - /* async queues get always the maximum possible budget - * (their ability to dispatch is limited by - * @bfqd->bfq_max_budget_async_rq). - */ + } else + /* + * Async queues get always the maximum possible budget + * (their ability to dispatch is limited by + * @bfqd->bfq_max_budget_async_rq). + */ budget = bfqd->bfq_max_budget; bfqq->max_budget = budget; - if (bfqd->budgets_assigned >= 194 && bfqd->bfq_user_max_budget == 0 && - bfqq->max_budget > bfqd->bfq_max_budget) - bfqq->max_budget = bfqd->bfq_max_budget; + if (bfqd->budgets_assigned >= bfq_stats_min_budgets && + !bfqd->bfq_user_max_budget) + bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget); /* * Make sure that we have enough budget for the next request. @@ -1960,14 +1984,14 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, * update. */ next_rq = bfqq->next_rq; - if (next_rq != NULL) + if (next_rq) bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget, bfq_serv_to_charge(next_rq, bfqq)); else bfqq->entity.budget = bfqq->max_budget; - bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %lu", - next_rq != NULL ? blk_rq_sectors(next_rq) : 0, + bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d", + next_rq ? blk_rq_sectors(next_rq) : 0, bfqq->entity.budget); } @@ -1993,15 +2017,15 @@ static unsigned long bfq_calc_max_budget(u64 peak_rate, u64 timeout) * seeky processes, and hence reduce their chances to lower the * throughput. See the code for more details. */ -static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, - int compensate, enum bfqq_expiration reason) +static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bool compensate, enum bfqq_expiration reason) { u64 bw, usecs, expected, timeout; ktime_t delta; int update = 0; if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq)) - return 0; + return false; if (compensate) delta = bfqd->last_idling_start; @@ -2012,7 +2036,7 @@ static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, /* Don't trust short/unrealistic values. */ if (usecs < 100 || usecs >= LONG_MAX) - return 0; + return false; /* * Calculate the bandwidth for the last slice. We use a 64 bit @@ -2061,7 +2085,7 @@ static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd->peak_rate, timeout); - bfq_log(bfqd, "new max_budget=%lu", + bfq_log(bfqd, "new max_budget=%d", bfqd->bfq_max_budget); } if (bfqd->device_speed == BFQ_BFQD_FAST && @@ -2086,7 +2110,7 @@ static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, * and for the moment return false. */ if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8) - return 0; + return false; /* * A process is considered ``slow'' (i.e., seeky, so that we @@ -2161,8 +2185,8 @@ static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, * seems to be quite precise also in embedded systems and KVM/QEMU virtual * machines. */ -static inline unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, - struct bfq_queue *bfqq) +static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, + struct bfq_queue *bfqq) { return max(bfqq->last_idle_bklogged + HZ * bfqq->service_from_backlogged / @@ -2175,7 +2199,7 @@ static inline unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, * the current time will be lower than this time instant according to the macro * time_is_before_jiffies(). */ -static inline unsigned long bfq_infinity_from_now(unsigned long now) +static unsigned long bfq_infinity_from_now(unsigned long now) { return now + ULONG_MAX / 2; } @@ -2212,13 +2236,14 @@ static inline unsigned long bfq_infinity_from_now(unsigned long now) */ static void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq, - int compensate, + bool compensate, enum bfqq_expiration reason) { - int slow; + bool slow; BUG_ON(bfqq != bfqd->in_service_queue); - /* Update disk peak rate for autotuning and check whether the + /* + * Update disk peak rate for autotuning and check whether the * process is slow (see bfq_update_peak_rate). */ slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason); @@ -2312,12 +2337,12 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd, * just checked on request arrivals and completions, as well as on * idle timer expirations. */ -static int bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) +static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) { if (bfq_bfqq_budget_new(bfqq) || time_before(jiffies, bfqq->budget_timeout)) - return 0; - return 1; + return false; + return true; } /* @@ -2328,7 +2353,7 @@ static int bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) * does not hold, or if the queue is slow enough to deserve only to be * kicked off for preserving a high throughput. */ -static inline int bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) +static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) { bfq_log_bfqq(bfqq->bfqd, bfqq, "may_budget_timeout: wait_request %d left %d timeout %d", @@ -2343,183 +2368,278 @@ static inline int bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) } /* - * Device idling is allowed only for the queues for which this function - * returns true. For this reason, the return value of this function plays a - * critical role for both throughput boosting and service guarantees. The - * return value is computed through a logical expression. In this rather - * long comment, we try to briefly describe all the details and motivations - * behind the components of this logical expression. - * - * First, the expression is false if bfqq is not sync, or if: bfqq happened - * to become active during a large burst of queue activations, and the - * pattern of requests bfqq contains boosts the throughput if bfqq is - * expired. In fact, queues that became active during a large burst benefit - * only from throughput, as discussed in the comments to bfq_handle_burst. - * In this respect, expiring bfqq certainly boosts the throughput on NCQ- - * capable flash-based devices, whereas, on rotational devices, it boosts - * the throughput only if bfqq contains random requests. - * - * On the opposite end, if (a) bfqq is sync, (b) the above burst-related - * condition does not hold, and (c) bfqq is being weight-raised, then the - * expression always evaluates to true, as device idling is instrumental - * for preserving low-latency guarantees (see [1]). If, instead, conditions - * (a) and (b) do hold, but (c) does not, then the expression evaluates to - * true only if: (1) bfqq is I/O-bound and has a non-null idle window, and - * (2) at least one of the following two conditions holds. - * The first condition is that the device is not performing NCQ, because - * idling the device most certainly boosts the throughput if this condition - * holds and bfqq is I/O-bound and has been granted a non-null idle window. - * The second compound condition is made of the logical AND of two components. - * - * The first component is true only if there is no weight-raised busy - * queue. This guarantees that the device is not idled for a sync non- - * weight-raised queue when there are busy weight-raised queues. The former - * is then expired immediately if empty. Combined with the timestamping - * rules of BFQ (see [1] for details), this causes sync non-weight-raised - * queues to get a lower number of requests served, and hence to ask for a - * lower number of requests from the request pool, before the busy weight- - * raised queues get served again. - * - * This is beneficial for the processes associated with weight-raised - * queues, when the request pool is saturated (e.g., in the presence of - * write hogs). In fact, if the processes associated with the other queues - * ask for requests at a lower rate, then weight-raised processes have a - * higher probability to get a request from the pool immediately (or at - * least soon) when they need one. Hence they have a higher probability to - * actually get a fraction of the disk throughput proportional to their - * high weight. This is especially true with NCQ-capable drives, which - * enqueue several requests in advance and further reorder internally- - * queued requests. - * - * In the end, mistreating non-weight-raised queues when there are busy - * weight-raised queues seems to mitigate starvation problems in the - * presence of heavy write workloads and NCQ, and hence to guarantee a - * higher application and system responsiveness in these hostile scenarios. - * - * If the first component of the compound condition is instead true, i.e., - * there is no weight-raised busy queue, then the second component of the - * compound condition takes into account service-guarantee and throughput - * issues related to NCQ (recall that the compound condition is evaluated - * only if the device is detected as supporting NCQ). + * For a queue that becomes empty, device idling is allowed only if + * this function returns true for that queue. As a consequence, since + * device idling plays a critical role for both throughput boosting + * and service guarantees, the return value of this function plays a + * critical role as well. * - * As for service guarantees, allowing the drive to enqueue more than one - * request at a time, and hence delegating de facto final scheduling - * decisions to the drive's internal scheduler, causes loss of control on - * the actual request service order. In this respect, when the drive is - * allowed to enqueue more than one request at a time, the service - * distribution enforced by the drive's internal scheduler is likely to - * coincide with the desired device-throughput distribution only in the - * following, perfectly symmetric, scenario: - * 1) all active queues have the same weight, - * 2) all active groups at the same level in the groups tree have the same - * weight, - * 3) all active groups at the same level in the groups tree have the same - * number of children. - * - * Even in such a scenario, sequential I/O may still receive a preferential - * treatment, but this is not likely to be a big issue with flash-based - * devices, because of their non-dramatic loss of throughput with random - * I/O. Things do differ with HDDs, for which additional care is taken, as - * explained after completing the discussion for flash-based devices. + * In a nutshell, this function returns true only if idling is + * beneficial for throughput or, even if detrimental for throughput, + * idling is however necessary to preserve service guarantees (low + * latency, desired throughput distribution, ...). In particular, on + * NCQ-capable devices, this function tries to return false, so as to + * help keep the drives' internal queues full, whenever this helps the + * device boost the throughput without causing any service-guarantee + * issue. * - * Unfortunately, keeping the necessary state for evaluating exactly the - * above symmetry conditions would be quite complex and time-consuming. - * Therefore BFQ evaluates instead the following stronger sub-conditions, - * for which it is much easier to maintain the needed state: - * 1) all active queues have the same weight, - * 2) all active groups have the same weight, - * 3) all active groups have at most one active child each. - * In particular, the last two conditions are always true if hierarchical - * support and the cgroups interface are not enabled, hence no state needs - * to be maintained in this case. - * - * According to the above considerations, the second component of the - * compound condition evaluates to true if any of the above symmetry - * sub-condition does not hold, or the device is not flash-based. Therefore, - * if also the first component is true, then idling is allowed for a sync - * queue. These are the only sub-conditions considered if the device is - * flash-based, as, for such a device, it is sensible to force idling only - * for service-guarantee issues. In fact, as for throughput, idling - * NCQ-capable flash-based devices would not boost the throughput even - * with sequential I/O; rather it would lower the throughput in proportion - * to how fast the device is. In the end, (only) if all the three - * sub-conditions hold and the device is flash-based, the compound - * condition evaluates to false and therefore no idling is performed. - * - * As already said, things change with a rotational device, where idling - * boosts the throughput with sequential I/O (even with NCQ). Hence, for - * such a device the second component of the compound condition evaluates - * to true also if the following additional sub-condition does not hold: - * the queue is constantly seeky. Unfortunately, this different behavior - * with respect to flash-based devices causes an additional asymmetry: if - * some sync queues enjoy idling and some other sync queues do not, then - * the latter get a low share of the device throughput, simply because the - * former get many requests served after being set as in service, whereas - * the latter do not. As a consequence, to guarantee the desired throughput - * distribution, on HDDs the compound expression evaluates to true (and - * hence device idling is performed) also if the following last symmetry - * condition does not hold: no other queue is benefiting from idling. Also - * this last condition is actually replaced with a simpler-to-maintain and - * stronger condition: there is no busy queue which is not constantly seeky - * (and hence may also benefit from idling). - * - * To sum up, when all the required symmetry and throughput-boosting - * sub-conditions hold, the second component of the compound condition - * evaluates to false, and hence no idling is performed. This helps to - * keep the drives' internal queues full on NCQ-capable devices, and hence - * to boost the throughput, without causing 'almost' any loss of service - * guarantees. The 'almost' follows from the fact that, if the internal - * queue of one such device is filled while all the sub-conditions hold, - * but at some point in time some sub-condition stops to hold, then it may - * become impossible to let requests be served in the new desired order - * until all the requests already queued in the device have been served. + * In more detail, the return value of this function is obtained by, + * first, computing a number of boolean variables that take into + * account throughput and service-guarantee issues, and, then, + * combining these variables in a logical expression. Most of the + * issues taken into account are not trivial. We discuss these issues + * while introducing the variables. */ -static inline bool bfq_bfqq_must_not_expire(struct bfq_queue *bfqq) +static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) { struct bfq_data *bfqd = bfqq->bfqd; -#define cond_for_seeky_on_ncq_hdd (bfq_bfqq_constantly_seeky(bfqq) && \ - bfqd->busy_in_flight_queues == \ - bfqd->const_seeky_busy_in_flight_queues) + bool idling_boosts_thr, idling_boosts_thr_without_issues, + all_queues_seeky, on_hdd_and_not_all_queues_seeky, + idling_needed_for_service_guarantees, + asymmetric_scenario; -#define cond_for_expiring_in_burst (bfq_bfqq_in_large_burst(bfqq) && \ - bfqd->hw_tag && \ - (blk_queue_nonrot(bfqd->queue) || \ - bfq_bfqq_constantly_seeky(bfqq))) + /* + * The next variable takes into account the cases where idling + * boosts the throughput. + * + * The value of the variable is computed considering, first, that + * idling is virtually always beneficial for the throughput if: + * (a) the device is not NCQ-capable, or + * (b) regardless of the presence of NCQ, the device is rotational + * and the request pattern for bfqq is I/O-bound and sequential. + * + * Secondly, and in contrast to the above item (b), idling an + * NCQ-capable flash-based device would not boost the + * throughput even with sequential I/O; rather it would lower + * the throughput in proportion to how fast the device + * is. Accordingly, the next variable is true if any of the + * above conditions (a) and (b) is true, and, in particular, + * happens to be false if bfqd is an NCQ-capable flash-based + * device. + */ + idling_boosts_thr = !bfqd->hw_tag || + (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) && + bfq_bfqq_idle_window(bfqq)) ; -/* - * Condition for expiring a non-weight-raised queue (and hence not idling - * the device). - */ -#define cond_for_expiring_non_wr (bfqd->hw_tag && \ - (bfqd->wr_busy_queues > 0 || \ - (blk_queue_nonrot(bfqd->queue) || \ - cond_for_seeky_on_ncq_hdd))) + /* + * The value of the next variable, + * idling_boosts_thr_without_issues, is equal to that of + * idling_boosts_thr, unless a special case holds. In this + * special case, described below, idling may cause problems to + * weight-raised queues. + * + * When the request pool is saturated (e.g., in the presence + * of write hogs), if the processes associated with + * non-weight-raised queues ask for requests at a lower rate, + * then processes associated with weight-raised queues have a + * higher probability to get a request from the pool + * immediately (or at least soon) when they need one. Thus + * they have a higher probability to actually get a fraction + * of the device throughput proportional to their high + * weight. This is especially true with NCQ-capable drives, + * which enqueue several requests in advance, and further + * reorder internally-queued requests. + * + * For this reason, we force to false the value of + * idling_boosts_thr_without_issues if there are weight-raised + * busy queues. In this case, and if bfqq is not weight-raised, + * this guarantees that the device is not idled for bfqq (if, + * instead, bfqq is weight-raised, then idling will be + * guaranteed by another variable, see below). Combined with + * the timestamping rules of BFQ (see [1] for details), this + * behavior causes bfqq, and hence any sync non-weight-raised + * queue, to get a lower number of requests served, and thus + * to ask for a lower number of requests from the request + * pool, before the busy weight-raised queues get served + * again. This often mitigates starvation problems in the + * presence of heavy write workloads and NCQ, thereby + * guaranteeing a higher application and system responsiveness + * in these hostile scenarios. + */ + idling_boosts_thr_without_issues = idling_boosts_thr && + bfqd->wr_busy_queues == 0; + + /* + * There are then two cases where idling must be performed not + * for throughput concerns, but to preserve service + * guarantees. In the description of these cases, we say, for + * short, that a queue is sequential/random if the process + * associated to the queue issues sequential/random requests + * (in the second case the queue may be tagged as seeky or + * even constantly_seeky). + * + * To introduce the first case, we note that, since + * bfq_bfqq_idle_window(bfqq) is false if the device is + * NCQ-capable and bfqq is random (see + * bfq_update_idle_window()), then, from the above two + * assignments it follows that + * idling_boosts_thr_without_issues is false if the device is + * NCQ-capable and bfqq is random. Therefore, for this case, + * device idling would never be allowed if we used just + * idling_boosts_thr_without_issues to decide whether to allow + * it. And, beneficially, this would imply that throughput + * would always be boosted also with random I/O on NCQ-capable + * HDDs. + * + * But we must be careful on this point, to avoid an unfair + * treatment for bfqq. In fact, because of the same above + * assignments, idling_boosts_thr_without_issues is, on the + * other hand, true if 1) the device is an HDD and bfqq is + * sequential, and 2) there are no busy weight-raised + * queues. As a consequence, if we used just + * idling_boosts_thr_without_issues to decide whether to idle + * the device, then with an HDD we might easily bump into a + * scenario where queues that are sequential and I/O-bound + * would enjoy idling, whereas random queues would not. The + * latter might then get a low share of the device throughput, + * simply because the former would get many requests served + * after being set as in service, while the latter would not. + * + * To address this issue, we start by setting to true a + * sentinel variable, on_hdd_and_not_all_queues_seeky, if the + * device is rotational and not all queues with pending or + * in-flight requests are constantly seeky (i.e., there are + * active sequential queues, and bfqq might then be mistreated + * if it does not enjoy idling because it is random). + */ + all_queues_seeky = bfq_bfqq_constantly_seeky(bfqq) && + bfqd->busy_in_flight_queues == + bfqd->const_seeky_busy_in_flight_queues; + + on_hdd_and_not_all_queues_seeky = + !blk_queue_nonrot(bfqd->queue) && !all_queues_seeky; + + /* + * To introduce the second case where idling needs to be + * performed to preserve service guarantees, we can note that + * allowing the drive to enqueue more than one request at a + * time, and hence delegating de facto final scheduling + * decisions to the drive's internal scheduler, causes loss of + * control on the actual request service order. In particular, + * the critical situation is when requests from different + * processes happens to be present, at the same time, in the + * internal queue(s) of the drive. In such a situation, the + * drive, by deciding the service order of the + * internally-queued requests, does determine also the actual + * throughput distribution among these processes. But the + * drive typically has no notion or concern about per-process + * throughput distribution, and makes its decisions only on a + * per-request basis. Therefore, the service distribution + * enforced by the drive's internal scheduler is likely to + * coincide with the desired device-throughput distribution + * only in a completely symmetric scenario where: + * (i) each of these processes must get the same throughput as + * the others; + * (ii) all these processes have the same I/O pattern + (either sequential or random). + * In fact, in such a scenario, the drive will tend to treat + * the requests of each of these processes in about the same + * way as the requests of the others, and thus to provide + * each of these processes with about the same throughput + * (which is exactly the desired throughput distribution). In + * contrast, in any asymmetric scenario, device idling is + * certainly needed to guarantee that bfqq receives its + * assigned fraction of the device throughput (see [1] for + * details). + * + * We address this issue by controlling, actually, only the + * symmetry sub-condition (i), i.e., provided that + * sub-condition (i) holds, idling is not performed, + * regardless of whether sub-condition (ii) holds. In other + * words, only if sub-condition (i) holds, then idling is + * allowed, and the device tends to be prevented from queueing + * many requests, possibly of several processes. The reason + * for not controlling also sub-condition (ii) is that, first, + * in the case of an HDD, the asymmetry in terms of types of + * I/O patterns is already taken in to account in the above + * sentinel variable + * on_hdd_and_not_all_queues_seeky. Secondly, in the case of a + * flash-based device, we prefer however to privilege + * throughput (and idling lowers throughput for this type of + * devices), for the following reasons: + * 1) differently from HDDs, the service time of random + * requests is not orders of magnitudes lower than the service + * time of sequential requests; thus, even if processes doing + * sequential I/O get a preferential treatment with respect to + * others doing random I/O, the consequences are not as + * dramatic as with HDDs; + * 2) if a process doing random I/O does need strong + * throughput guarantees, it is hopefully already being + * weight-raised, or the user is likely to have assigned it a + * higher weight than the other processes (and thus + * sub-condition (i) is likely to be false, which triggers + * idling). + * + * According to the above considerations, the next variable is + * true (only) if sub-condition (i) holds. To compute the + * value of this variable, we not only use the return value of + * the function bfq_symmetric_scenario(), but also check + * whether bfqq is being weight-raised, because + * bfq_symmetric_scenario() does not take into account also + * weight-raised queues (see comments to + * bfq_weights_tree_add()). + * + * As a side note, it is worth considering that the above + * device-idling countermeasures may however fail in the + * following unlucky scenario: if idling is (correctly) + * disabled in a time period during which all symmetry + * sub-conditions hold, and hence the device is allowed to + * enqueue many requests, but at some later point in time some + * sub-condition stops to hold, then it may become impossible + * to let requests be served in the desired order until all + * the requests already queued in the device have been served. + */ + asymmetric_scenario = bfqq->wr_coeff > 1 || + !bfq_symmetric_scenario(bfqd); + + /* + * Finally, there is a case where maximizing throughput is the + * best choice even if it may cause unfairness toward + * bfqq. Such a case is when bfqq became active in a burst of + * queue activations. Queues that became active during a large + * burst benefit only from throughput, as discussed in the + * comments to bfq_handle_burst. Thus, if bfqq became active + * in a burst and not idling the device maximizes throughput, + * then the device must no be idled, because not idling the + * device provides bfqq and all other queues in the burst with + * maximum benefit. Combining this and the two cases above, we + * can now establish when idling is actually needed to + * preserve service guarantees. + */ + idling_needed_for_service_guarantees = + (on_hdd_and_not_all_queues_seeky || asymmetric_scenario) && + !bfq_bfqq_in_large_burst(bfqq); + /* + * We have now all the components we need to compute the return + * value of the function, which is true only if both the following + * conditions hold: + * 1) bfqq is sync, because idling make sense only for sync queues; + * 2) idling either boosts the throughput (without issues), or + * is necessary to preserve service guarantees. + */ return bfq_bfqq_sync(bfqq) && - !cond_for_expiring_in_burst && - (bfqq->wr_coeff > 1 || !symmetric_scenario || - (bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_idle_window(bfqq) && - !cond_for_expiring_non_wr) - ); + (idling_boosts_thr_without_issues || + idling_needed_for_service_guarantees); } /* - * If the in-service queue is empty but sync, and the function - * bfq_bfqq_must_not_expire returns true, then: + * If the in-service queue is empty but the function bfq_bfqq_may_idle + * returns true, then: * 1) the queue must remain in service and cannot be expired, and - * 2) the disk must be idled to wait for the possible arrival of a new + * 2) the device must be idled to wait for the possible arrival of a new * request for the queue. - * See the comments to the function bfq_bfqq_must_not_expire for the reasons + * See the comments to the function bfq_bfqq_may_idle for the reasons * why performing device idling is the best choice to boost the throughput - * and preserve service guarantees when bfq_bfqq_must_not_expire itself + * and preserve service guarantees when bfq_bfqq_may_idle itself * returns true. */ -static inline bool bfq_bfqq_must_idle(struct bfq_queue *bfqq) +static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq) { struct bfq_data *bfqd = bfqq->bfqd; return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 && - bfq_bfqq_must_not_expire(bfqq); + bfq_bfqq_may_idle(bfqq); } /* @@ -2533,7 +2653,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT; bfqq = bfqd->in_service_queue; - if (bfqq == NULL) + if (!bfqq) goto new_queue; bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue"); @@ -2548,7 +2668,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) * If bfqq has requests queued and it has enough budget left to * serve them, keep the queue, otherwise expire it. */ - if (next_rq != NULL) { + if (next_rq) { if (bfq_serv_to_charge(next_rq, bfqq) > bfq_bfqq_budget_left(bfqq)) { reason = BFQ_BFQQ_BUDGET_EXHAUSTED; @@ -2575,6 +2695,9 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) */ bfq_clear_bfqq_wait_request(bfqq); del_timer(&bfqd->idle_slice_timer); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_idle_time(bfqq_group(bfqq)); +#endif } goto keep_queue; } @@ -2586,18 +2709,18 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) * may idle after their completion, then keep it anyway. */ if (timer_pending(&bfqd->idle_slice_timer) || - (bfqq->dispatched != 0 && bfq_bfqq_must_not_expire(bfqq))) { + (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) { bfqq = NULL; goto keep_queue; } reason = BFQ_BFQQ_NO_MORE_REQUESTS; expire: - bfq_bfqq_expire(bfqd, bfqq, 0, reason); + bfq_bfqq_expire(bfqd, bfqq, false, reason); new_queue: bfqq = bfq_set_in_service_queue(bfqd); bfq_log(bfqd, "select_queue: new queue %d returned", - bfqq != NULL ? bfqq->pid : 0); + bfqq ? bfqq->pid : 0); keep_queue: return bfqq; } @@ -2615,7 +2738,7 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq) BUG_ON(bfqq != bfqd->in_service_queue && entity->weight != entity->orig_weight * bfqq->wr_coeff); - if (entity->ioprio_changed) + if (entity->prio_changed) bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change"); /* @@ -2659,7 +2782,7 @@ static int bfq_dispatch_request(struct bfq_data *bfqd, /* Follow expired path, else get first next available. */ rq = bfq_check_fifo(bfqq); - if (rq == NULL) + if (!rq) rq = bfqq->next_rq; service_to_charge = bfq_serv_to_charge(rq, bfqq); @@ -2695,14 +2818,14 @@ static int bfq_dispatch_request(struct bfq_data *bfqd, bfq_update_wr_data(bfqd, bfqq); bfq_log_bfqq(bfqd, bfqq, - "dispatched %u sec req (%llu), budg left %lu", + "dispatched %u sec req (%llu), budg left %d", blk_rq_sectors(rq), (long long unsigned)blk_rq_pos(rq), bfq_bfqq_budget_left(bfqq)); dispatched++; - if (bfqd->in_service_bic == NULL) { + if (!bfqd->in_service_bic) { atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount); bfqd->in_service_bic = RQ_BIC(rq); } @@ -2715,7 +2838,7 @@ static int bfq_dispatch_request(struct bfq_data *bfqd, return dispatched; expire: - bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_EXHAUSTED); + bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED); return dispatched; } @@ -2723,7 +2846,7 @@ static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq) { int dispatched = 0; - while (bfqq->next_rq != NULL) { + while (bfqq->next_rq) { bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq); dispatched++; } @@ -2743,7 +2866,7 @@ static int bfq_forced_dispatch(struct bfq_data *bfqd) int dispatched = 0; bfqq = bfqd->in_service_queue; - if (bfqq != NULL) + if (bfqq) __bfq_bfqq_expire(bfqd, bfqq); /* @@ -2779,7 +2902,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force) return bfq_forced_dispatch(bfqd); bfqq = bfq_select_queue(bfqd); - if (bfqq == NULL) + if (!bfqq) return 0; if (bfq_class_idle(bfqq)) @@ -2819,6 +2942,9 @@ static int bfq_dispatch_requests(struct request_queue *q, int force) static void bfq_put_queue(struct bfq_queue *bfqq) { struct bfq_data *bfqd = bfqq->bfqd; +#ifdef CONFIG_BFQ_GROUP_IOSCHED + struct bfq_group *bfqg = bfqq_group(bfqq); +#endif BUG_ON(atomic_read(&bfqq->ref) <= 0); @@ -2827,9 +2953,9 @@ static void bfq_put_queue(struct bfq_queue *bfqq) if (!atomic_dec_and_test(&bfqq->ref)) return; - BUG_ON(rb_first(&bfqq->sort_list) != NULL); + BUG_ON(rb_first(&bfqq->sort_list)); BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0); - BUG_ON(bfqq->entity.tree != NULL); + BUG_ON(bfqq->entity.tree); BUG_ON(bfq_bfqq_busy(bfqq)); BUG_ON(bfqd->in_service_queue == bfqq); @@ -2847,6 +2973,9 @@ static void bfq_put_queue(struct bfq_queue *bfqq) bfq_log_bfqq(bfqd, bfqq, "put_queue: %p freed", bfqq); kmem_cache_free(bfq_pool, bfqq); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_put(bfqg); +#endif } static void bfq_put_cooperator(struct bfq_queue *bfqq) @@ -2883,7 +3012,7 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) bfq_put_queue(bfqq); } -static inline void bfq_init_icq(struct io_cq *icq) +static void bfq_init_icq(struct io_cq *icq) { struct bfq_io_cq *bic = icq_to_bic(icq); @@ -2950,40 +3079,38 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *b /* * No prio set, inherit CPU scheduling settings. */ - bfqq->entity.new_ioprio = task_nice_ioprio(tsk); - bfqq->entity.new_ioprio_class = task_nice_ioclass(tsk); + bfqq->new_ioprio = task_nice_ioprio(tsk); + bfqq->new_ioprio_class = task_nice_ioclass(tsk); break; case IOPRIO_CLASS_RT: - bfqq->entity.new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); - bfqq->entity.new_ioprio_class = IOPRIO_CLASS_RT; + bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); + bfqq->new_ioprio_class = IOPRIO_CLASS_RT; break; case IOPRIO_CLASS_BE: - bfqq->entity.new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); - bfqq->entity.new_ioprio_class = IOPRIO_CLASS_BE; + bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); + bfqq->new_ioprio_class = IOPRIO_CLASS_BE; break; case IOPRIO_CLASS_IDLE: - bfqq->entity.new_ioprio_class = IOPRIO_CLASS_IDLE; - bfqq->entity.new_ioprio = 7; + bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE; + bfqq->new_ioprio = 7; bfq_clear_bfqq_idle_window(bfqq); break; } - if (bfqq->entity.new_ioprio < 0 || - bfqq->entity.new_ioprio >= IOPRIO_BE_NR) { + if (bfqq->new_ioprio < 0 || bfqq->new_ioprio >= IOPRIO_BE_NR) { printk(KERN_CRIT "bfq_set_next_ioprio_data: new_ioprio %d\n", - bfqq->entity.new_ioprio); + bfqq->new_ioprio); BUG(); } - bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->entity.new_ioprio); - bfqq->entity.ioprio_changed = 1; + bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio); + bfqq->entity.prio_changed = 1; } -static void bfq_check_ioprio_change(struct bfq_io_cq *bic) +static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio) { struct bfq_data *bfqd; struct bfq_queue *bfqq, *new_bfqq; - struct bfq_group *bfqg; unsigned long uninitialized_var(flags); int ioprio = bic->icq.ioc->ioprio; @@ -2993,18 +3120,16 @@ static void bfq_check_ioprio_change(struct bfq_io_cq *bic) * This condition may trigger on a newly created bic, be sure to * drop the lock before returning. */ - if (unlikely(bfqd == NULL) || likely(bic->ioprio == ioprio)) + if (unlikely(!bfqd) || likely(bic->ioprio == ioprio)) goto out; bic->ioprio = ioprio; bfqq = bic->bfqq[BLK_RW_ASYNC]; - if (bfqq != NULL) { - bfqg = container_of(bfqq->entity.sched_data, struct bfq_group, - sched_data); - new_bfqq = bfq_get_queue(bfqd, bfqg, BLK_RW_ASYNC, bic, + if (bfqq) { + new_bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic, GFP_ATOMIC); - if (new_bfqq != NULL) { + if (new_bfqq) { bic->bfqq[BLK_RW_ASYNC] = new_bfqq; bfq_log_bfqq(bfqd, bfqq, "check_ioprio_change: bfqq %p %d", @@ -3014,7 +3139,7 @@ static void bfq_check_ioprio_change(struct bfq_io_cq *bic) } bfqq = bic->bfqq[BLK_RW_SYNC]; - if (bfqq != NULL) + if (bfqq) bfq_set_next_ioprio_data(bfqq, bic); out: @@ -3038,7 +3163,8 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, if (!bfq_class_idle(bfqq)) bfq_mark_bfqq_idle_window(bfqq); bfq_mark_bfqq_sync(bfqq); - } + } else + bfq_clear_bfqq_sync(bfqq); bfq_mark_bfqq_IO_bound(bfqq); /* Tentative initial value to trade off between thr and lat */ @@ -3055,14 +3181,19 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, } static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd, - struct bfq_group *bfqg, - int is_sync, + struct bio *bio, int is_sync, struct bfq_io_cq *bic, gfp_t gfp_mask) { + struct bfq_group *bfqg; struct bfq_queue *bfqq, *new_bfqq = NULL; + struct blkcg *blkcg; retry: + rcu_read_lock(); + + blkcg = bio_blkcg(bio); + bfqg = bfq_find_alloc_group(bfqd, blkcg); /* bic always exists here */ bfqq = bic_to_bfqq(bic, is_sync); @@ -3070,18 +3201,19 @@ retry: * Always try a new alloc if we fall back to the OOM bfqq * originally, since it should just be a temporary situation. */ - if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) { + if (!bfqq || bfqq == &bfqd->oom_bfqq) { bfqq = NULL; - if (new_bfqq != NULL) { + if (new_bfqq) { bfqq = new_bfqq; new_bfqq = NULL; } else if (gfp_mask & __GFP_WAIT) { + rcu_read_unlock(); spin_unlock_irq(bfqd->queue->queue_lock); new_bfqq = kmem_cache_alloc_node(bfq_pool, gfp_mask | __GFP_ZERO, bfqd->queue->node); spin_lock_irq(bfqd->queue->queue_lock); - if (new_bfqq != NULL) + if (new_bfqq) goto retry; } else { bfqq = kmem_cache_alloc_node(bfq_pool, @@ -3089,7 +3221,7 @@ retry: bfqd->queue->node); } - if (bfqq != NULL) { + if (bfqq) { bfq_init_bfqq(bfqd, bfqq, bic, current->pid, is_sync); bfq_init_entity(&bfqq->entity, bfqg); @@ -3100,9 +3232,11 @@ retry: } } - if (new_bfqq != NULL) + if (new_bfqq) kmem_cache_free(bfq_pool, new_bfqq); + rcu_read_unlock(); + return bfqq; } @@ -3126,7 +3260,7 @@ static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, } static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, - struct bfq_group *bfqg, int is_sync, + struct bio *bio, int is_sync, struct bfq_io_cq *bic, gfp_t gfp_mask) { const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio); @@ -3135,19 +3269,26 @@ static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, struct bfq_queue *bfqq = NULL; if (!is_sync) { + struct blkcg *blkcg; + struct bfq_group *bfqg; + + rcu_read_lock(); + blkcg = bio_blkcg(bio); + rcu_read_unlock(); + bfqg = bfq_find_alloc_group(bfqd, blkcg); async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class, ioprio); bfqq = *async_bfqq; } - if (bfqq == NULL) - bfqq = bfq_find_alloc_queue(bfqd, bfqg, is_sync, bic, gfp_mask); + if (!bfqq) + bfqq = bfq_find_alloc_queue(bfqd, bio, is_sync, bic, gfp_mask); /* * Pin the queue now that it's allocated, scheduler exit will * prune it. */ - if (!is_sync && *async_bfqq == NULL) { + if (!is_sync && !(*async_bfqq)) { atomic_inc(&bfqq->ref); bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d", bfqq, atomic_read(&bfqq->ref)); @@ -3280,9 +3421,9 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) { - int small_req = bfqq->queued[rq_is_sync(rq)] == 1 && - blk_rq_sectors(rq) < 32; - int budget_timeout = bfq_bfqq_budget_timeout(bfqq); + bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 && + blk_rq_sectors(rq) < 32; + bool budget_timeout = bfq_bfqq_budget_timeout(bfqq); /* * There is just this request queued: if the request @@ -3309,6 +3450,9 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, */ bfq_clear_bfqq_wait_request(bfqq); del_timer(&bfqd->idle_slice_timer); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_idle_time(bfqq_group(bfqq)); +#endif /* * The queue is not empty, because a new request just @@ -3318,7 +3462,8 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, * See [1] for more details. */ if (budget_timeout) - bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_TIMEOUT); + bfq_bfqq_expire(bfqd, bfqq, false, + BFQ_BFQQ_BUDGET_TIMEOUT); /* * Let the request rip immediately, or let a new queue be @@ -3342,7 +3487,7 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq) */ if (!in_interrupt()) { new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true); - if (new_bfqq != NULL) { + if (new_bfqq) { if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq) new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1); /* @@ -3370,7 +3515,7 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq) * from assigning it a full weight-raising period. See the detailed * comments about this field in bfq_init_icq(). */ - if (bfqq->bic != NULL) + if (bfqq->bic) bfqq->bic->wr_time_left = 0; rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; list_add_tail(&rq->queuelist, &bfqq->fifo); @@ -3418,6 +3563,11 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq) BUG_ON(!bfqq->dispatched); bfqd->rq_in_driver--; bfqq->dispatched--; +#ifdef CONFIG_BFQ_GROUP_IOSCHED + bfqg_stats_update_completion(bfqq_group(bfqq), + rq_start_time_ns(rq), + rq_io_start_time_ns(rq), rq->cmd_flags); +#endif if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) { bfq_weights_tree_remove(bfqd, &bfqq->entity, @@ -3462,11 +3612,12 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq) bfq_arm_slice_timer(bfqd); goto out; } else if (bfq_may_expire_for_budg_timeout(bfqq)) - bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_TIMEOUT); + bfq_bfqq_expire(bfqd, bfqq, false, + BFQ_BFQQ_BUDGET_TIMEOUT); else if (RB_EMPTY_ROOT(&bfqq->sort_list) && (bfqq->dispatched == 0 || - !bfq_bfqq_must_not_expire(bfqq))) - bfq_bfqq_expire(bfqd, bfqq, 0, + !bfq_bfqq_may_idle(bfqq))) + bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_NO_MORE_REQUESTS); } @@ -3477,7 +3628,7 @@ out: return; } -static inline int __bfq_may_queue(struct bfq_queue *bfqq) +static int __bfq_may_queue(struct bfq_queue *bfqq) { if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) { bfq_clear_bfqq_must_alloc(bfqq); @@ -3501,11 +3652,11 @@ static int bfq_may_queue(struct request_queue *q, int rw) * 'may queue' if that fails. */ bic = bfq_bic_lookup(bfqd, tsk->io_context); - if (bic == NULL) + if (!bic) return ELV_MQUEUE_MAY; bfqq = bic_to_bfqq(bic, rw_is_sync(rw)); - if (bfqq != NULL) + if (bfqq) return __bfq_may_queue(bfqq); return ELV_MQUEUE_MAY; @@ -3518,7 +3669,7 @@ static void bfq_put_request(struct request *rq) { struct bfq_queue *bfqq = RQ_BFQQ(rq); - if (bfqq != NULL) { + if (bfqq) { const int rw = rq_data_dir(rq); BUG_ON(!bfqq->allocated[rw]); @@ -3570,25 +3721,24 @@ static int bfq_set_request(struct request_queue *q, struct request *rq, const int rw = rq_data_dir(rq); const int is_sync = rq_is_sync(rq); struct bfq_queue *bfqq; - struct bfq_group *bfqg; unsigned long flags; bool split = false; might_sleep_if(gfp_mask & __GFP_WAIT); - bfq_check_ioprio_change(bic); + bfq_check_ioprio_change(bic, bio); spin_lock_irqsave(q->queue_lock, flags); - if (bic == NULL) + if (!bic) goto queue_fail; - bfqg = bfq_bic_update_cgroup(bic); + bfq_bic_update_cgroup(bic, bio); new_queue: bfqq = bic_to_bfqq(bic, is_sync); - if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) { - bfqq = bfq_get_queue(bfqd, bfqg, is_sync, bic, gfp_mask); + if (!bfqq || bfqq == &bfqd->oom_bfqq) { + bfqq = bfq_get_queue(bfqd, bio, is_sync, bic, gfp_mask); bic_set_bfqq(bic, bfqq, is_sync); if (split && is_sync) { if ((bic->was_in_burst_list && bfqd->large_burst) || @@ -3684,7 +3834,7 @@ static void bfq_idle_slice_timer(unsigned long data) * the in-service queue. This can hardly happen, but in the worst * case we just expire a queue too early. */ - if (bfqq != NULL) { + if (bfqq) { bfq_log_bfqq(bfqd, bfqq, "slice_timer expired"); if (bfq_bfqq_budget_timeout(bfqq)) /* @@ -3704,7 +3854,7 @@ static void bfq_idle_slice_timer(unsigned long data) else goto schedule_dispatch; - bfq_bfqq_expire(bfqd, bfqq, 1, reason); + bfq_bfqq_expire(bfqd, bfqq, true, reason); } schedule_dispatch: @@ -3719,14 +3869,14 @@ static void bfq_shutdown_timer_wq(struct bfq_data *bfqd) cancel_work_sync(&bfqd->unplug_work); } -static inline void __bfq_put_async_bfqq(struct bfq_data *bfqd, +static void __bfq_put_async_bfqq(struct bfq_data *bfqd, struct bfq_queue **bfqq_ptr) { struct bfq_group *root_group = bfqd->root_group; struct bfq_queue *bfqq = *bfqq_ptr; bfq_log(bfqd, "put_async_bfqq: %p", bfqq); - if (bfqq != NULL) { + if (bfqq) { bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group); bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d", bfqq, atomic_read(&bfqq->ref)); @@ -3762,7 +3912,7 @@ static void bfq_exit_queue(struct elevator_queue *e) spin_lock_irq(q->queue_lock); - BUG_ON(bfqd->in_service_queue != NULL); + BUG_ON(bfqd->in_service_queue); list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) bfq_deactivate_bfqq(bfqd, bfqq, 0); @@ -3775,22 +3925,39 @@ static void bfq_exit_queue(struct elevator_queue *e) BUG_ON(timer_pending(&bfqd->idle_slice_timer)); - bfq_free_root_group(bfqd); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + blkcg_deactivate_policy(q, &blkcg_policy_bfq); +#endif + kfree(bfqd); } +static void bfq_init_root_group(struct bfq_group *root_group, + struct bfq_data *bfqd) +{ + int i; + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + root_group->entity.parent = NULL; + root_group->my_entity = NULL; + root_group->bfqd = bfqd; +#endif + root_group->rq_pos_tree = RB_ROOT; + for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) + root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; +} + static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) { - struct bfq_group *bfqg; struct bfq_data *bfqd; struct elevator_queue *eq; eq = elevator_alloc(q, e); - if (eq == NULL) + if (!eq) return -ENOMEM; bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node); - if (bfqd == NULL) { + if (!bfqd) { kobject_put(&eq->kobj); return -ENOMEM; } @@ -3803,16 +3970,16 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) */ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0); atomic_inc(&bfqd->oom_bfqq.ref); - bfqd->oom_bfqq.entity.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO; - bfqd->oom_bfqq.entity.new_ioprio_class = IOPRIO_CLASS_BE; + bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO; + bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE; bfqd->oom_bfqq.entity.new_weight = - bfq_ioprio_to_weight(bfqd->oom_bfqq.entity.new_ioprio); + bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio); /* * Trigger weight initialization, according to ioprio, at the * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio * class won't be changed any more. */ - bfqd->oom_bfqq.entity.ioprio_changed = 1; + bfqd->oom_bfqq.entity.prio_changed = 1; bfqd->queue = q; @@ -3820,16 +3987,12 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) q->elevator = eq; spin_unlock_irq(q->queue_lock); - bfqg = bfq_alloc_root_group(bfqd, q->node); - if (bfqg == NULL) { - kfree(bfqd); - kobject_put(&eq->kobj); - return -ENOMEM; - } - - bfqd->root_group = bfqg; + bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node); + if (!bfqd->root_group) + goto out_free; + bfq_init_root_group(bfqd->root_group, bfqd); bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group); -#ifdef CONFIG_CGROUP_BFQIO +#ifdef CONFIG_BFQ_GROUP_IOSCHED bfqd->active_numerous_groups = 0; #endif @@ -3837,7 +4000,6 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) bfqd->idle_slice_timer.function = bfq_idle_slice_timer; bfqd->idle_slice_timer.data = (unsigned long)bfqd; - bfqd->rq_pos_tree = RB_ROOT; bfqd->queue_weights_tree = RB_ROOT; bfqd->group_weights_tree = RB_ROOT; @@ -3895,18 +4057,23 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) bfqd->device_speed = BFQ_BFQD_FAST; return 0; + +out_free: + kfree(bfqd); + kobject_put(&eq->kobj); + return -ENOMEM; } static void bfq_slab_kill(void) { - if (bfq_pool != NULL) + if (bfq_pool) kmem_cache_destroy(bfq_pool); } static int __init bfq_slab_setup(void) { bfq_pool = KMEM_CACHE(bfq_queue, 0); - if (bfq_pool == NULL) + if (!bfq_pool) return -ENOMEM; return 0; } @@ -4051,7 +4218,7 @@ static ssize_t bfq_weights_store(struct elevator_queue *e, return count; } -static inline unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd) +static unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd) { u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]); @@ -4145,6 +4312,9 @@ static struct elevator_type iosched_bfq = { .elevator_merge_fn = bfq_merge, .elevator_merged_fn = bfq_merged_request, .elevator_merge_req_fn = bfq_merged_requests, +#ifdef CONFIG_BFQ_GROUP_IOSCHED + .elevator_bio_merged_fn = bfq_bio_merged, +#endif .elevator_allow_merge_fn = bfq_allow_merge, .elevator_dispatch_fn = bfq_dispatch_requests, .elevator_add_req_fn = bfq_insert_request, @@ -4170,6 +4340,8 @@ static struct elevator_type iosched_bfq = { static int __init bfq_init(void) { + int ret; + /* * Can be 0 on HZ < 1000 setups. */ @@ -4179,8 +4351,15 @@ static int __init bfq_init(void) if (bfq_timeout_async == 0) bfq_timeout_async = 1; +#ifdef CONFIG_BFQ_GROUP_IOSCHED + ret = blkcg_policy_register(&blkcg_policy_bfq); + if (ret) + return ret; +#endif + + ret = -ENOMEM; if (bfq_slab_setup()) - return -ENOMEM; + goto err_pol_unreg; /* * Times to load large popular applications for the typical systems @@ -4199,15 +4378,27 @@ static int __init bfq_init(void) device_speed_thresh[0] = (R_fast[0] + R_slow[0]) / 2; device_speed_thresh[1] = (R_fast[1] + R_slow[1]) / 2; - elv_register(&iosched_bfq); - pr_info("BFQ I/O-scheduler: v7r8"); + ret = elv_register(&iosched_bfq); + if (ret) + goto err_pol_unreg; + + pr_info("BFQ I/O-scheduler: v7r9"); return 0; + +err_pol_unreg: +#ifdef CONFIG_BFQ_GROUP_IOSCHED + blkcg_policy_unregister(&blkcg_policy_bfq); +#endif + return ret; } static void __exit bfq_exit(void) { elv_unregister(&iosched_bfq); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + blkcg_policy_unregister(&blkcg_policy_bfq); +#endif bfq_slab_kill(); } |