[dpdk-dev] [PATCH 3/5] net/mlx4: refine setting Tx completion flag

[Moti Haimovsky]

PMD now take into consideration the amount of entries in the TxQ
a packet occupies when choosing weather to set the report-completion flag
to the chip or not.

Signed-off-by: Moti Haimovsky <motih at mellanox.com>
---
 drivers/net/mlx4/mlx4_rxtx.c | 30 +++++++++++-------------------
 drivers/net/mlx4/mlx4_rxtx.h |  2 +-
 2 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/drivers/net/mlx4/mlx4_rxtx.c b/drivers/net/mlx4/mlx4_rxtx.c
index e41ea9e..dae0e47 100644
--- a/drivers/net/mlx4/mlx4_rxtx.c
+++ b/drivers/net/mlx4/mlx4_rxtx.c
@@ -461,14 +461,16 @@
 	/* Fill-in date from last to first */
 	for (i = wr->num_sge  - 1; i >= 0; --i)
 		mlx4_set_data_seg(dseg + i,  wr->sg_list + i);
-	/* Handle control info
-	 *
-	 * For raw eth, the SOLICIT flag is used to indicate that
-	 * no icrc should be calculated
-	 */
-	srcrb_flags = MLX4_WQE_CTRL_SOLICIT |
-		      ((wr->send_flags & IBV_SEND_SIGNALED) ?
-				      MLX4_WQE_CTRL_CQ_UPDATE : 0);
+	/* Handle control info */
+	/* For raw eth always set the SOLICIT flag */
+	/*  Request Tx completion. */
+	txq->elts_comp_cd -= nr_txbbs;
+	if (unlikely(txq->elts_comp_cd <= 0)) {
+		srcrb_flags = MLX4_WQE_CTRL_SOLICIT | MLX4_WQE_CTRL_CQ_UPDATE;
+		txq->elts_comp_cd = txq->elts_comp_cd_init;
+	} else {
+		srcrb_flags = MLX4_WQE_CTRL_SOLICIT;
+	}
 	fence_size = (wr->send_flags & IBV_SEND_FENCE ?
 		MLX4_WQE_CTRL_FENCE : 0) | ((wqe_real_size / 16) & 0x3f);
 	owner_opcode = MLX4_OPCODE_SEND |
@@ -514,13 +516,12 @@
 	struct ibv_send_wr *wr_bad = NULL;
 	unsigned int elts_head = txq->elts_head;
 	const unsigned int elts_n = txq->elts_n;
-	unsigned int elts_comp_cd = txq->elts_comp_cd;
 	unsigned int elts_comp = 0;
 	unsigned int i;
 	unsigned int max;
 	int err;
 
-	assert(elts_comp_cd != 0);
+	assert(txq->elts_comp_cd != 0);
 	mlx4_txq_complete(txq);
 	max = (elts_n - (elts_head - txq->elts_tail));
 	if (max > elts_n)
@@ -560,11 +561,6 @@
 				tmp = next;
 			} while (tmp != NULL);
 		}
-		/* Request Tx completion. */
-		if (unlikely(--elts_comp_cd == 0)) {
-			elts_comp_cd = txq->elts_comp_cd_init;
-			send_flags |= IBV_SEND_SIGNALED;
-		}
 		if (buf->pkt_len <= txq->max_inline)
 			send_flags |= IBV_SEND_INLINE;
 		/* Update element. */
@@ -580,9 +576,6 @@
 		/* post the pkt for sending */
 		err = mlx4_post_send(txq, buf, wr, &wr_bad);
 		if (unlikely(err)) {
-			if (unlikely(wr_bad->send_flags &
-				     IBV_SEND_SIGNALED))
-				elts_comp_cd = 1;
 			elt->buf = NULL;
 			goto stop;
 		}
@@ -602,7 +595,6 @@
 	mlx4_send_flush(txq);
 	txq->elts_head = elts_head;
 	txq->elts_comp += elts_comp;
-	txq->elts_comp_cd = elts_comp_cd;
 	return i;
 }
 
diff --git a/drivers/net/mlx4/mlx4_rxtx.h b/drivers/net/mlx4/mlx4_rxtx.h
index 7cae7e2..35e0de7 100644
--- a/drivers/net/mlx4/mlx4_rxtx.h
+++ b/drivers/net/mlx4/mlx4_rxtx.h
@@ -140,7 +140,7 @@ struct txq {
 	unsigned int elts_head; /**< Current index in (*elts)[]. */
 	unsigned int elts_tail; /**< First element awaiting completion. */
 	unsigned int elts_comp; /**< Number of pkts waiting for completion. */
-	unsigned int elts_comp_cd; /**< Countdown for next completion. */
+	int elts_comp_cd; /**< Countdown for next completion. */
 	unsigned int elts_comp_cd_init; /**< Initial value for countdown. */
 	struct mlx4_txq_stats stats; /**< Tx queue counters. */
 	unsigned int socket; /**< CPU socket ID for allocations. */
-- 
1.8.3.1