[PATCH V2 1/3] blk-mq: use list_splice_tail_init() to insert requests

Ming Lei
2018-06-29T08:12:50Z

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: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 22fe394d0b49..359382b59d40 100644
--- 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);
}
--
2.9.5