blk-mq: use list_splice_tail_init() to insert requests

list_splice_tail_init() is much more faster than inserting each
request one by one, given all requets in 'list' belong to
same sw queue and ctx->lock is required to insert requests.

Cc: Laurence Oberman <loberman@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Tested-by: Kashyap Desai <kashyap.desai@broadcom.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index acf31ad733bfb17c7f93f3dfb23059a98c5c57e2..795ba859b16b672f775eacc34fe7bdb6473ee1fc 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1545,19 +1545,19 @@ void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
                            struct list_head *list)
 
 {
+       struct request *rq;
+
        /*
         * preemption doesn't flush plug list, so it's possible ctx->cpu is
         * offline now
         */
-       spin_lock(&ctx->lock);
-       while (!list_empty(list)) {
-               struct request *rq;
-
-               rq = list_first_entry(list, struct request, queuelist);
+       list_for_each_entry(rq, list, queuelist) {
                BUG_ON(rq->mq_ctx != ctx);
-               list_del_init(&rq->queuelist);
-               __blk_mq_insert_req_list(hctx, rq, false);
+               trace_block_rq_insert(hctx->queue, rq);
        }
+
+       spin_lock(&ctx->lock);
+       list_splice_tail_init(list, &ctx->rq_list);
        blk_mq_hctx_mark_pending(hctx, ctx);
        spin_unlock(&ctx->lock);
 }