In case of shared tags, hctx_may_queue() limits that the maximum number of requests allocated to one hw queue is .queue_depth / active_queues.
So we try to allow to use hw tag for this case if .queue_depth/shared_queues is not less than q->nr_requests. This can cover some scsi devices too, such as virtio-scsi in default configuration. Signed-off-by: Ming Lei <[email protected]> --- block/blk-mq-sched.c | 16 ++++++++-------- block/blk-mq-sched.h | 1 + block/blk-mq.c | 21 ++++++++++++++++++--- block/blk-mq.h | 23 +++++++++++++++++++++++ 4 files changed, 50 insertions(+), 11 deletions(-) diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index a7e125a40e0a..f2114eb3eebb 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -459,8 +459,7 @@ static int blk_mq_set_queue_depth(struct blk_mq_hw_ctx *hctx, return blk_mq_tag_update_depth(hctx, &hctx->tags, nr, false); } -static int blk_mq_set_queues_depth(struct request_queue *q, - unsigned int nr) +int blk_mq_set_queues_depth(struct request_queue *q, unsigned int nr) { struct blk_mq_hw_ctx *hctx; int i, j, ret; @@ -543,15 +542,14 @@ void blk_mq_sched_exit_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx, } /* - * If this queue has enough hardware tags and doesn't share tags with - * other queues, just use hw tag directly for scheduling. + * If this queue has enough hardware tags, just use hw tag directly + * for scheduling. */ bool blk_mq_sched_may_use_hw_tag(struct request_queue *q) { - if (q->tag_set->flags & BLK_MQ_F_TAG_SHARED) - return false; + int nr_shared = blk_mq_get_shared_queues(q); - if (q->act_hw_queue_depth < q->nr_requests) + if ((q->act_hw_queue_depth / nr_shared) < q->nr_requests) return false; return true; @@ -578,8 +576,10 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e) auto_hw_tag = blk_mq_sched_may_use_hw_tag(q); if (auto_hw_tag) { + unsigned int nr_shared = blk_mq_get_shared_queues(q); + q->act_hw_queue_depth = blk_mq_get_queue_depth(q); - if (blk_mq_set_queues_depth(q, q->nr_requests)) + if (blk_mq_set_queues_depth(q, q->nr_requests * nr_shared)) auto_hw_tag = false; } diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h index bbfc1ea5fafa..6deca4f9e656 100644 --- a/block/blk-mq-sched.h +++ b/block/blk-mq-sched.h @@ -26,6 +26,7 @@ void blk_mq_sched_insert_requests(struct request_queue *q, void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx); bool blk_mq_sched_may_use_hw_tag(struct request_queue *q); +int blk_mq_set_queues_depth(struct request_queue *q, unsigned int nr); int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e); void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e); diff --git a/block/blk-mq.c b/block/blk-mq.c index e02fa8d078e6..401a04388ac9 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2150,15 +2150,17 @@ int blk_mq_get_queue_depth(struct request_queue *q) return tags->bitmap_tags.sb.depth + tags->breserved_tags.sb.depth; } -static void blk_mq_update_sched_flag(struct request_queue *q) +static bool blk_mq_update_sched_flag(struct request_queue *q) { struct blk_mq_hw_ctx *hctx; int i; + bool use_hw_tag; if (!q->elevator) - return; + return false; - if (!blk_mq_sched_may_use_hw_tag(q)) + use_hw_tag = blk_mq_sched_may_use_hw_tag(q); + if (!use_hw_tag) queue_for_each_hw_ctx(q, hctx, i) { if (hctx->flags & BLK_MQ_F_SCHED_USE_HW_TAG) { blk_mq_set_queue_depth(hctx, q->act_hw_queue_depth); @@ -2176,6 +2178,16 @@ static void blk_mq_update_sched_flag(struct request_queue *q) if (hctx->sched_tags) blk_mq_sched_free_tags(q->tag_set, hctx, i); } + return use_hw_tag; +} + +static void blk_mq_update_for_sched(struct request_queue *q) +{ + if (!blk_mq_update_sched_flag(q)) + return; + + blk_mq_set_queues_depth(q, q->nr_requests * + __blk_mq_get_shared_queues(q)); } static void queue_set_hctx_shared(struct request_queue *q, bool shared) @@ -2217,6 +2229,8 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q) /* update existing queue */ blk_mq_update_tag_set_depth(set, false); } + + blk_mq_update_for_sched(q); mutex_unlock(&set->tag_list_lock); synchronize_rcu(); @@ -2239,6 +2253,7 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set, queue_set_hctx_shared(q, true); list_add_tail_rcu(&q->tag_set_list, &set->tag_list); + blk_mq_update_for_sched(q); mutex_unlock(&set->tag_list_lock); } diff --git a/block/blk-mq.h b/block/blk-mq.h index d49d46de2923..3fd869bee744 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -150,4 +150,27 @@ static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx) return hctx->nr_ctx && hctx->tags; } +/* return how many queues shared tag set with me */ +static inline int __blk_mq_get_shared_queues(struct request_queue *q) +{ + struct blk_mq_tag_set *set = q->tag_set; + int nr = 0; + + list_for_each_entry_rcu(q, &set->tag_list, tag_set_list) + nr++; + return nr; +} + +static inline int blk_mq_get_shared_queues(struct request_queue *q) +{ + int nr = 0; + struct blk_mq_tag_set *set = q->tag_set; + + mutex_lock(&set->tag_list_lock); + nr = __blk_mq_get_shared_queues(q); + mutex_unlock(&set->tag_list_lock); + + return nr; +} + #endif -- 2.9.3
