[PATCH v2 5/5] block/null_blk: add queue_rqs() support

chengming.zhou
2023-09-13T15:17:22Z

From: Chengming Zhou <zhouchengming@bytedance.com>

Add batched mq_ops.queue_rqs() support in null_blk for testing. The
implementation is much easy since null_blk doesn't have commit_rqs().

We simply handle each request one by one, if errors are encountered,
leave them in the passed in list and return back.

There is about 3.6% improvement in IOPS of fio/t/io_uring on null_blk
with hw_queue_depth=256 on my test VM, from 1.09M to 1.13M.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
drivers/block/null_blk/main.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 968090935eb2..79d6cd3c3d41 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1750,6 +1750,25 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
return null_handle_cmd(cmd, sector, nr_sectors, req_op(rq));
}

+static void null_queue_rqs(struct request **rqlist)
+{
+ struct request *requeue_list = NULL;
+ struct request **requeue_lastp = &requeue_list;
+ struct blk_mq_queue_data bd = { };
+ blk_status_t ret;
+
+ do {
+ struct request *rq = rq_list_pop(rqlist);
+
+ bd.rq = rq;
+ ret = null_queue_rq(rq->mq_hctx, &bd);
+ if (ret != BLK_STS_OK)
+ rq_list_add_tail(&requeue_lastp, rq);
+ } while (!rq_list_empty(*rqlist));
+
+ *rqlist = requeue_list;
+}
+
static void cleanup_queue(struct nullb_queue *nq)
{
bitmap_free(nq->tag_map);
@@ -1802,6 +1821,7 @@ static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,

static const struct blk_mq_ops null_mq_ops = {
.queue_rq = null_queue_rq,
+ .queue_rqs = null_queue_rqs,
.complete = null_complete_rq,
.timeout = null_timeout_rq,
.poll = null_poll,
--
2.40.1