[dpdk-dev] [PATCH 06/14] mlx4: fix available entries in TX rings

[Adrien Mazarguil]

From: Nelio Laranjeiro <nelio.laranje...@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: 7fae69eeff13 ("mlx4: new poll mode driver")

Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro at 6wind.com>
Signed-off-by: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
---
 drivers/net/mlx4/mlx4.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index 3e05373..4f57e2d 100644
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -1306,7 +1306,6 @@ mlx4_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;
@@ -1316,7 +1315,7 @@ mlx4_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