[dpdk-dev] [PATCH 13/14] mlx5: fix available entries in TX rings

[Adrien Mazarguil]

From: Nelio Laranjeiro <nelio.laranjeiro at 6wind.com>

The number of available entries in TX rings is taken before performing
completion, effectively making rings smaller than they are and causing
TX performance issues under load.

Fixes: 2e22920b85d9 ("mlx5: support non-scattered Tx and Rx")

Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro at 6wind.com>
Signed-off-by: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
---
 drivers/net/mlx5/mlx5_rxtx.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index eb6c9f7..fa5e648 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -436,7 +436,6 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 {
 	struct txq *txq = (struct txq *)dpdk_txq;
 	unsigned int elts_head = txq->elts_head;
-	const unsigned int elts_tail = txq->elts_tail;
 	const unsigned int elts_n = txq->elts_n;
 	unsigned int elts_comp_cd = txq->elts_comp_cd;
 	unsigned int elts_comp = 0;
@@ -446,7 +445,7 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 
 	assert(elts_comp_cd != 0);
 	txq_complete(txq);
-	max = (elts_n - (elts_head - elts_tail));
+	max = (elts_n - (elts_head - txq->elts_tail));
 	if (max > elts_n)
 		max -= elts_n;
 	assert(max >= 1);
-- 
2.1.0