mlx4: prefetch completed Tx mbufs before releasing them

Signed-off-by: Alex Rosenbaum <alexr@mellanox.com>
Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index f251eb4..52f3fbb 100644 (file)
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -1205,6 +1205,9 @@ mlx4_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
                max = pkts_n;
        for (i = 0; (i != max); ++i) {
                struct rte_mbuf *buf = pkts[i];
+               unsigned int elts_head_next =
+                       (((elts_head + 1) == elts_n) ? 0 : elts_head + 1);
+               struct txq_elt *elt_next = &(*txq->elts)[elts_head_next];
                struct txq_elt *elt = &(*txq->elts)[elts_head];
                unsigned int segs = NB_SEGS(buf);
 #ifdef MLX4_PMD_SOFT_COUNTERS
@@ -1253,6 +1256,7 @@ mlx4_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
                        if (txq->priv->vf)
                                rte_prefetch0((volatile void *)
                                              (uintptr_t)addr);
+                       RTE_MBUF_PREFETCH_TO_FREE(elt_next->buf);
                        /* Put packet into send queue. */
 #if MLX4_PMD_MAX_INLINE > 0
                        if (length <= txq->max_inline)
@@ -1283,6 +1287,7 @@ mlx4_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
                                          &sges);
                        if (ret.length == (unsigned int)-1)
                                goto stop;
+                       RTE_MBUF_PREFETCH_TO_FREE(elt_next->buf);
                        /* Put SG list into send queue. */
                        err = txq->if_qp->send_pending_sg_list
                                (txq->qp,
@@ -1300,8 +1305,7 @@ mlx4_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
                        goto stop;
 #endif /* MLX4_PMD_SGE_WR_N > 1 */
                }
-               if (++elts_head >= elts_n)
-                       elts_head = 0;
+               elts_head = elts_head_next;
 #ifdef MLX4_PMD_SOFT_COUNTERS
                /* Increment sent bytes counter. */
                txq->stats.obytes += sent_size;