blk-mq: cache request hardware queue mapping

We call blk_mq_map_queue() a lot, at least two times for each
request per IO, sometimes more. Since we now have an indirect
call as well in that function. cache the mapping so we don't
have to re-call blk_mq_map_queue() for the same request
multiple times.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 2 insertions, 4 deletions

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index bbabc3877d5a..641df3f00632 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -366,9 +366,7 @@ void blk_mq_sched_insert_request(struct request *rq, bool at_head,
 	struct request_queue *q = rq->q;
 	struct elevator_queue *e = q->elevator;
 	struct blk_mq_ctx *ctx = rq->mq_ctx;
-	struct blk_mq_hw_ctx *hctx;
-
-	hctx = blk_mq_map_queue(q, rq->cmd_flags, ctx->cpu);
+	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
 
 	/* flush rq in flush machinery need to be dispatched directly */
 	if (!(rq->rq_flags & RQF_FLUSH_SEQ) && op_is_flush(rq->cmd_flags)) {
@@ -407,7 +405,7 @@ void blk_mq_sched_insert_requests(struct request_queue *q,
 
 	/* For list inserts, requests better be on the same hw queue */
 	rq = list_first_entry(list, struct request, queuelist);
-	hctx = blk_mq_map_queue(q, rq->cmd_flags, ctx->cpu);
+	hctx = rq->mq_hctx;
 
 	e = hctx->queue->elevator;
 	if (e && e->type->ops.insert_requests)