Re: [PATCH 3/4] nvme-rdma: use new shared CQ mechanism

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On 5/10/2020 5:55 PM, Yamin Friedman wrote:
Has the driver use shared CQs providing ~10%-50% improvement as seen in the
patch introducing shared CQs. Instead of opening a CQ on each core per NS
connected, a CQ for each core will be provided by the core driver that will
be shared between the QPs on that core reducing interrupt overhead.

Signed-off-by: Yamin Friedman <yaminf@xxxxxxxxxxxx>
Reviewed-by: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
---
  drivers/nvme/host/rdma.c | 65 ++++++++++++++++++++++++++++++++----------------
  1 file changed, 43 insertions(+), 22 deletions(-)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index cac8a93..23eefd7 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -85,6 +85,7 @@ struct nvme_rdma_queue {
  	struct rdma_cm_id	*cm_id;
  	int			cm_error;
  	struct completion	cm_done;
+	int			cq_size;
  };
struct nvme_rdma_ctrl {
@@ -261,6 +262,7 @@ static int nvme_rdma_create_qp(struct nvme_rdma_queue *queue, const int factor)
  	init_attr.qp_type = IB_QPT_RC;
  	init_attr.send_cq = queue->ib_cq;
  	init_attr.recv_cq = queue->ib_cq;
+	init_attr.qp_context = queue;
ret = rdma_create_qp(queue->cm_id, dev->pd, &init_attr); @@ -389,6 +391,15 @@ static int nvme_rdma_dev_get(struct nvme_rdma_device *dev)
  	return NULL;
  }
+static void nvme_rdma_free_cq(struct nvme_rdma_queue *queue)
+{
+	if (nvme_rdma_poll_queue(queue))
+		ib_free_cq(queue->ib_cq);
+	else {
+		ib_cq_pool_put(queue->ib_cq, queue->cq_size);
+	}
+}

somehow I missed it in the internal review:

	if (nvme_rdma_poll_queue(queue))
		ib_free_cq(queue->ib_cq);
	else
		ib_cq_pool_put(queue->ib_cq, queue->cq_size);


+
  static void nvme_rdma_destroy_queue_ib(struct nvme_rdma_queue *queue)
  {
  	struct nvme_rdma_device *dev;
@@ -408,7 +419,7 @@ static void nvme_rdma_destroy_queue_ib(struct nvme_rdma_queue *queue)
  	 * the destruction of the QP shouldn't use rdma_cm API.
  	 */
  	ib_destroy_qp(queue->qp);
-	ib_free_cq(queue->ib_cq);
+	nvme_rdma_free_cq(queue);
nvme_rdma_free_ring(ibdev, queue->rsp_ring, queue->queue_size,
  			sizeof(struct nvme_completion), DMA_FROM_DEVICE);
@@ -422,13 +433,35 @@ static int nvme_rdma_get_max_fr_pages(struct ib_device *ibdev)
  		     ibdev->attrs.max_fast_reg_page_list_len - 1);
  }
+static void nvme_rdma_create_cq(struct ib_device *ibdev,
+				struct nvme_rdma_queue *queue)
+{
+	int comp_vector, idx = nvme_rdma_queue_idx(queue);
+	enum ib_poll_context poll_ctx;
+
+	/*
+	 * Spread I/O queues completion vectors according their queue index.
+	 * Admin queues can always go on completion vector 0.
+	 */
+	comp_vector = idx == 0 ? idx : idx - 1;
+
+	/* Polling queues need direct cq polling context */
+	if (nvme_rdma_poll_queue(queue)) {
+		poll_ctx = IB_POLL_DIRECT;
+		queue->ib_cq = ib_alloc_cq(ibdev, queue, queue->cq_size,
+					   comp_vector, poll_ctx);
+	} else {
+		poll_ctx = IB_POLL_SOFTIRQ;
+		queue->ib_cq = ib_cq_pool_get(ibdev, queue->cq_size,
+					      comp_vector, poll_ctx);
+	}

please add integer as return value here instead of void.

And check the return value in the caller.


+}
+
  static int nvme_rdma_create_queue_ib(struct nvme_rdma_queue *queue)
  {
  	struct ib_device *ibdev;
  	const int send_wr_factor = 3;			/* MR, SEND, INV */
  	const int cq_factor = send_wr_factor + 1;	/* + RECV */
-	int comp_vector, idx = nvme_rdma_queue_idx(queue);
-	enum ib_poll_context poll_ctx;
  	int ret, pages_per_mr;
queue->device = nvme_rdma_find_get_device(queue->cm_id);
@@ -439,22 +472,10 @@ static int nvme_rdma_create_queue_ib(struct nvme_rdma_queue *queue)
  	}
  	ibdev = queue->device->dev;
- /*
-	 * Spread I/O queues completion vectors according their queue index.
-	 * Admin queues can always go on completion vector 0.
-	 */
-	comp_vector = idx == 0 ? idx : idx - 1;
-
-	/* Polling queues need direct cq polling context */
-	if (nvme_rdma_poll_queue(queue))
-		poll_ctx = IB_POLL_DIRECT;
-	else
-		poll_ctx = IB_POLL_SOFTIRQ;
-
  	/* +1 for ib_stop_cq */
-	queue->ib_cq = ib_alloc_cq(ibdev, queue,
-				cq_factor * queue->queue_size + 1,
-				comp_vector, poll_ctx);
+	queue->cq_size = cq_factor * queue->queue_size + 1;
+
+	nvme_rdma_create_cq(ibdev, queue);

see above.


  	if (IS_ERR(queue->ib_cq)) {
  		ret = PTR_ERR(queue->ib_cq);
  		goto out_put_dev;
@@ -484,7 +505,7 @@ static int nvme_rdma_create_queue_ib(struct nvme_rdma_queue *queue)
  	if (ret) {
  		dev_err(queue->ctrl->ctrl.device,
  			"failed to initialize MR pool sized %d for QID %d\n",
-			queue->queue_size, idx);
+			queue->queue_size, nvme_rdma_queue_idx(queue));
  		goto out_destroy_ring;
  	}
@@ -498,7 +519,7 @@ static int nvme_rdma_create_queue_ib(struct nvme_rdma_queue *queue)
  out_destroy_qp:
  	rdma_destroy_qp(queue->cm_id);
  out_destroy_ib_cq:
-	ib_free_cq(queue->ib_cq);
+	nvme_rdma_free_cq(queue);
  out_put_dev:
  	nvme_rdma_dev_put(queue->device);
  	return ret;
@@ -1093,7 +1114,7 @@ static void nvme_rdma_error_recovery(struct nvme_rdma_ctrl *ctrl)
  static void nvme_rdma_wr_error(struct ib_cq *cq, struct ib_wc *wc,
  		const char *op)
  {
-	struct nvme_rdma_queue *queue = cq->cq_context;
+	struct nvme_rdma_queue *queue = wc->qp->qp_context;
  	struct nvme_rdma_ctrl *ctrl = queue->ctrl;
if (ctrl->ctrl.state == NVME_CTRL_LIVE)
@@ -1481,7 +1502,7 @@ static void nvme_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc)
  {
  	struct nvme_rdma_qe *qe =
  		container_of(wc->wr_cqe, struct nvme_rdma_qe, cqe);
-	struct nvme_rdma_queue *queue = cq->cq_context;
+	struct nvme_rdma_queue *queue = wc->qp->qp_context;
  	struct ib_device *ibdev = queue->device->dev;
  	struct nvme_completion *cqe = qe->data;
  	const size_t len = sizeof(struct nvme_completion);

with the above small fixes:

Reviewed-by: Max Gurtovoy <maxg@xxxxxxxxxxxx>





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