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From: Pankaj Raghav <[email protected]>
To: [email protected], [email protected]
Cc: [email protected], [email protected],
	[email protected], [email protected], [email protected],
	[email protected], [email protected], [email protected]
Subject: [PATCH v3 2/5] block: wire-up support for passthrough plugging
Date: Tue,  3 May 2022 20:48:28 +0200	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

From: Jens Axboe <[email protected]>

Add support for plugging in passthrough path. When plugging is enabled, the
requests are added to a plug instead of getting dispatched to the driver.
And when the plug is finished, the whole batch gets dispatched via
->queue_rqs which turns out to be more efficient. Otherwise dispatching
used to happen via ->queue_rq, one request at a time.

Signed-off-by: Jens Axboe <[email protected]>
---
 block/blk-mq.c | 90 ++++++++++++++++++++++++++------------------------
 1 file changed, 47 insertions(+), 43 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 84d749511f55..e432e7e8fe20 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2340,6 +2340,40 @@ void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 	blk_mq_hctx_mark_pending(hctx, ctx);
 }
 
+/*
+ * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
+ * queues. This is important for md arrays to benefit from merging
+ * requests.
+ */
+static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
+{
+	if (plug->multiple_queues)
+		return BLK_MAX_REQUEST_COUNT * 2;
+	return BLK_MAX_REQUEST_COUNT;
+}
+
+static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
+{
+	struct request *last = rq_list_peek(&plug->mq_list);
+
+	if (!plug->rq_count) {
+		trace_block_plug(rq->q);
+	} else if (plug->rq_count >= blk_plug_max_rq_count(plug) ||
+		   (!blk_queue_nomerges(rq->q) &&
+		    blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
+		blk_mq_flush_plug_list(plug, false);
+		trace_block_plug(rq->q);
+	}
+
+	if (!plug->multiple_queues && last && last->q != rq->q)
+		plug->multiple_queues = true;
+	if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))
+		plug->has_elevator = true;
+	rq->rq_next = NULL;
+	rq_list_add(&plug->mq_list, rq);
+	plug->rq_count++;
+}
+
 /**
  * blk_mq_request_bypass_insert - Insert a request at dispatch list.
  * @rq: Pointer to request to be inserted.
@@ -2353,16 +2387,20 @@ void blk_mq_request_bypass_insert(struct request *rq, bool at_head,
 				  bool run_queue)
 {
 	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
+	struct blk_plug *plug = current->plug;
 
-	spin_lock(&hctx->lock);
-	if (at_head)
-		list_add(&rq->queuelist, &hctx->dispatch);
-	else
-		list_add_tail(&rq->queuelist, &hctx->dispatch);
-	spin_unlock(&hctx->lock);
-
-	if (run_queue)
-		blk_mq_run_hw_queue(hctx, false);
+	if (plug) {
+		blk_add_rq_to_plug(plug, rq);
+	} else {
+		spin_lock(&hctx->lock);
+		if (at_head)
+			list_add(&rq->queuelist, &hctx->dispatch);
+		else
+			list_add_tail(&rq->queuelist, &hctx->dispatch);
+		spin_unlock(&hctx->lock);
+		if (run_queue)
+			blk_mq_run_hw_queue(hctx, false);
+	}
 }
 
 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
@@ -2676,40 +2714,6 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
 		hctx->queue->mq_ops->commit_rqs(hctx);
 }
 
-/*
- * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
- * queues. This is important for md arrays to benefit from merging
- * requests.
- */
-static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
-{
-	if (plug->multiple_queues)
-		return BLK_MAX_REQUEST_COUNT * 2;
-	return BLK_MAX_REQUEST_COUNT;
-}
-
-static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
-{
-	struct request *last = rq_list_peek(&plug->mq_list);
-
-	if (!plug->rq_count) {
-		trace_block_plug(rq->q);
-	} else if (plug->rq_count >= blk_plug_max_rq_count(plug) ||
-		   (!blk_queue_nomerges(rq->q) &&
-		    blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
-		blk_mq_flush_plug_list(plug, false);
-		trace_block_plug(rq->q);
-	}
-
-	if (!plug->multiple_queues && last && last->q != rq->q)
-		plug->multiple_queues = true;
-	if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))
-		plug->has_elevator = true;
-	rq->rq_next = NULL;
-	rq_list_add(&plug->mq_list, rq);
-	plug->rq_count++;
-}
-
 static bool blk_mq_attempt_bio_merge(struct request_queue *q,
 				     struct bio *bio, unsigned int nr_segs)
 {
-- 
2.25.1


  parent reply	other threads:[~2022-05-03 18:49 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20220503184911eucas1p1beb172219537d78fcaf2a1417f532cf7@eucas1p1.samsung.com>
2022-05-03 18:48 ` [PATCH v3 0/5] io_uring passthough for nvme Pankaj Raghav
     [not found]   ` <CGME20220503184912eucas1p1bb0e3d36c06cfde8436df3a45e67bd32@eucas1p1.samsung.com>
2022-05-03 18:48     ` [PATCH v3 1/5] fs,io_uring: add infrastructure for uring-cmd Pankaj Raghav
2022-05-03 20:52       ` Christoph Hellwig
2022-05-04 15:12         ` Kanchan Joshi
2022-05-04 12:09           ` Jens Axboe
2022-05-04 15:48           ` Kanchan Joshi
2022-05-03 21:03       ` Jens Axboe
     [not found]   ` <CGME20220503184913eucas1p156abb6e2273c8dabc22e87ec8b218a5c@eucas1p1.samsung.com>
2022-05-03 18:48     ` Pankaj Raghav [this message]
2022-05-03 20:53       ` [PATCH v3 2/5] block: wire-up support for passthrough plugging Christoph Hellwig
     [not found]   ` <CGME20220503184914eucas1p1d9df18afe3234c0698a66cdb9c664ddc@eucas1p1.samsung.com>
2022-05-03 18:48     ` [PATCH v3 3/5] nvme: refactor nvme_submit_user_cmd() Pankaj Raghav
     [not found]   ` <CGME20220503184915eucas1p2ae04772900c24ef0b23fd8bedead20ae@eucas1p2.samsung.com>
2022-05-03 18:48     ` [PATCH v3 4/5] nvme: wire-up uring-cmd support for io-passthru on char-device Pankaj Raghav
2022-05-03 20:55       ` Christoph Hellwig
     [not found]   ` <CGME20220503184916eucas1p266cbb3ffc1622b292bf59b5eccec9933@eucas1p2.samsung.com>
2022-05-03 18:48     ` [PATCH v3 5/5] nvme: add vectored-io support for uring-cmd Pankaj Raghav
2022-05-03 20:56       ` Christoph Hellwig

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