net/mlx4: remove unnecessary Tx wraparound checks

There is no need to check Tx queue wraparound for segments which are
not at the beginning of a Tx block. Especially relevant in a single
segment case.

Remove unnecessary aforementioned checks from Tx path.

Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

diff --git a/drivers/net/mlx4/mlx4_rxtx.c b/drivers/net/mlx4/mlx4_rxtx.c
index 5a78bc0..146c654 100644 (file)
--- a/drivers/net/mlx4/mlx4_rxtx.c
+++ b/drivers/net/mlx4/mlx4_rxtx.c
@@ -461,15 +461,11 @@ mlx4_tx_burst_segs(struct rte_mbuf *buf, struct txq *txq,
        for (sbuf = buf; sbuf != NULL; sbuf = sbuf->next, dseg++) {
                addr = rte_pktmbuf_mtod(sbuf, uintptr_t);
                rte_prefetch0((volatile void *)addr);
-               /* Handle WQE wraparound. */
-               if (dseg >= (volatile struct mlx4_wqe_data_seg *)sq->eob)
-                       dseg = (volatile struct mlx4_wqe_data_seg *)sq->buf;
-               dseg->addr = rte_cpu_to_be_64(addr);
                /* Memory region key (big endian) for this memory pool. */
                lkey = mlx4_txq_mp2mr(txq, mlx4_txq_mb2mp(sbuf));
                dseg->lkey = rte_cpu_to_be_32(lkey);
                /* Calculate the needed work queue entry size for this packet */
-               if (unlikely(dseg->lkey == rte_cpu_to_be_32((uint32_t)-1))) {
+               if (unlikely(lkey == rte_cpu_to_be_32((uint32_t)-1))) {
                        /* MR does not exist. */
                        DEBUG("%p: unable to get MP <-> MR association",
                                        (void *)txq);
@@ -501,6 +497,8 @@ mlx4_tx_burst_segs(struct rte_mbuf *buf, struct txq *txq,
                 * control segment.
                 */
                if ((uintptr_t)dseg & (uintptr_t)(MLX4_TXBB_SIZE - 1)) {
+                       dseg->addr = rte_cpu_to_be_64(addr);
+                       dseg->lkey = rte_cpu_to_be_32(lkey);
 #if RTE_CACHE_LINE_SIZE < 64
                        /*
                         * Need a barrier here before writing the byte_count
@@ -520,6 +518,13 @@ mlx4_tx_burst_segs(struct rte_mbuf *buf, struct txq *txq,
                         * TXBB, so we need to postpone its byte_count writing
                         * for later.
                         */
+                       /* Handle WQE wraparound. */
+                       if (dseg >=
+                           (volatile struct mlx4_wqe_data_seg *)sq->eob)
+                               dseg = (volatile struct mlx4_wqe_data_seg *)
+                                       sq->buf;
+                       dseg->addr = rte_cpu_to_be_64(addr);
+                       dseg->lkey = rte_cpu_to_be_32(lkey);
                        pv[pv_counter].dseg = dseg;
                        pv[pv_counter++].val = byte_count;
                }
@@ -625,11 +630,6 @@ mlx4_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
                                        sizeof(struct mlx4_wqe_ctrl_seg));
                        addr = rte_pktmbuf_mtod(buf, uintptr_t);
                        rte_prefetch0((volatile void *)addr);
-                       /* Handle WQE wraparound. */
-                       if (dseg >=
-                               (volatile struct mlx4_wqe_data_seg *)sq->eob)
-                               dseg = (volatile struct mlx4_wqe_data_seg *)
-                                               sq->buf;
                        dseg->addr = rte_cpu_to_be_64(addr);
                        /* Memory region key (big endian). */
                        lkey = mlx4_txq_mp2mr(txq, mlx4_txq_mb2mp(buf));