diff mbox series

[04/12] blk-mq: complete polled requests directly

Message ID 20200611064452.12353-5-hch@lst.de (mailing list archive)
State New, archived
Headers show
Series [01/12] blk-mq: merge blk-softirq.c into blk-mq.c | expand

Commit Message

Christoph Hellwig June 11, 2020, 6:44 a.m. UTC 
Even for single queue devices there is no point in offloading a polled
completion to the softirq, given that blk_mq_force_complete_rq is called
from the polling thread in that case and thus there are no starvation
issues.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-mq.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

Comments

Daniel Wagner June 18, 2020, 3:50 p.m. UTC | #1 
On Thu, Jun 11, 2020 at 08:44:44AM +0200, Christoph Hellwig wrote:
> Even for single queue devices there is no point in offloading a polled
> completion to the softirq, given that blk_mq_force_complete_rq is called
> from the polling thread in that case and thus there are no starvation
> issues.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Daniel Wagner <dwagner@suse.de>
diff mbox series

Patch

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9d3928456af1c8..25ce40b367a635 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -703,6 +703,16 @@  void blk_mq_force_complete_rq(struct request *rq)
 	int cpu;
 
 	WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
+
+	/*
+	 * For a polled request, always complete locallly, it's pointless
+	 * to redirect the completion.
+	 */
+	if (rq->cmd_flags & REQ_HIPRI) {
+		q->mq_ops->complete(rq);
+		return;
+	}
+
 	/*
 	 * Most of single queue controllers, there is only one irq vector
 	 * for handling IO completion, and the only irq's affinity is set
@@ -717,12 +727,7 @@  void blk_mq_force_complete_rq(struct request *rq)
 		return;
 	}
 
-	/*
-	 * For a polled request, always complete locallly, it's pointless
-	 * to redirect the completion.
-	 */
-	if ((rq->cmd_flags & REQ_HIPRI) ||
-	    !test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
+	if (!test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
 		q->mq_ops->complete(rq);
 		return;
 	}