[PATCH V10 3/4] blk-mq: issue directly with bypass 'false' in blk_mq_sched_insert_requests

From: Jianchao Wang
Date: Wed Dec 05 2018 - 22:33:48 EST


It is not necessary to issue request directly with bypass 'true'
in blk_mq_sched_insert_requests and handle the non-issued requests
itself. Just set bypass to 'false' and let blk_mq_try_issue_directly
handle them totally. Remove the blk_rq_can_direct_dispatch check,
because blk_mq_try_issue_directly can handle it well.

With respect to commit_rqs hook, we only need to care about the last
request's result. If it is inserted, invoke commit_rqs.

Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
---
block/blk-mq-sched.c | 8 +++-----
block/blk-mq.c | 26 +++++++++-----------------
2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index f096d898..5b4d52d 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -417,12 +417,10 @@ void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx,
* busy in case of 'none' scheduler, and this way may save
* us one extra enqueue & dequeue to sw queue.
*/
- if (!hctx->dispatch_busy && !e && !run_queue_async) {
+ if (!hctx->dispatch_busy && !e && !run_queue_async)
blk_mq_try_issue_list_directly(hctx, list);
- if (list_empty(list))
- return;
- }
- blk_mq_insert_requests(hctx, ctx, list);
+ else
+ blk_mq_insert_requests(hctx, ctx, list);
}

blk_mq_run_hw_queue(hctx, run_queue_async);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index a1cccdd..dd07fe1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1896,32 +1896,24 @@ blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
struct list_head *list)
{
+ blk_qc_t unused;
+ blk_status_t ret = BLK_STS_OK;
+
while (!list_empty(list)) {
- blk_status_t ret;
struct request *rq = list_first_entry(list, struct request,
queuelist);

- if (!blk_rq_can_direct_dispatch(rq))
- break;
-
list_del_init(&rq->queuelist);
- ret = blk_mq_request_issue_directly(rq, list_empty(list));
- if (ret != BLK_STS_OK) {
- if (ret == BLK_STS_RESOURCE ||
- ret == BLK_STS_DEV_RESOURCE) {
- list_add(&rq->queuelist, list);
- break;
- }
- blk_mq_end_request(rq, ret);
- }
+ ret = blk_mq_try_issue_directly(hctx, rq, &unused, false,
+ list_empty(list));
}

/*
- * If we didn't flush the entire list, we could have told
- * the driver there was more coming, but that turned out to
- * be a lie.
+ * We only need to care about the last request's result,
+ * if it is inserted, kick the hardware with commit_rqs hook.
*/
- if (!list_empty(list) && hctx->queue->mq_ops->commit_rqs)
+ if ((ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) &&
+ hctx->queue->mq_ops->commit_rqs)
hctx->queue->mq_ops->commit_rqs(hctx);
}

--
2.7.4