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 <ming.lei@xxxxxxxxxx> --- block/blk-mq-sched.h | 10 ++++++---- block/blk-mq.c | 1 + block/blk-mq.h | 11 +++++++++++ 3 files changed, 18 insertions(+), 4 deletions(-) diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h index 241d23c18181..b0c124b59e17 100644 --- a/block/blk-mq-sched.h +++ b/block/blk-mq-sched.h @@ -137,15 +137,17 @@ static inline bool blk_mq_sched_needs_restart(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. */ static inline bool blk_mq_sched_may_use_hw_tag(struct request_queue *q) { + int nr_shared = 1; + if (q->tag_set->flags & BLK_MQ_F_TAG_SHARED) - return false; + nr_shared = blk_mq_get_shared_queues(q); - if (blk_mq_get_queue_depth(q) < q->nr_requests) + if ((blk_mq_get_queue_depth(q) / nr_shared) < q->nr_requests) return false; return true; diff --git a/block/blk-mq.c b/block/blk-mq.c index 0d9433680b2a..c4ca4336fa69 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2179,6 +2179,7 @@ static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared) list_for_each_entry(q, &set->tag_list, tag_set_list) { blk_mq_freeze_queue(q); queue_set_hctx_shared(q, shared); + blk_mq_update_sched_flag(q); blk_mq_unfreeze_queue(q); } } diff --git a/block/blk-mq.h b/block/blk-mq.h index 8085d5989cf5..351f266ec3a7 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -178,4 +178,15 @@ 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; +} + #endif -- 2.9.3