net/mlx4_en: XDP_TX, assign constant values of TX descs on ring creaion

In XDP_TX, some fields in tx_info and tx_desc are constants across
all entries of the different XDP_TX rings.
Assign values to these fields on ring creation time, rather than in
data-path.

Patchset performance tests:
Tested on ConnectX3Pro, Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz
Single queue no-RSS optimization ON.

XDP_TX packet rate:
------------------------------
Before    | After     | Gain |
13.7 Mpps | 14.0 Mpps | %2.2 |
------------------------------

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index e4c7a80ef5a8111742a4a05d49a790e908d06d85..d611df2f274d54d9ce837e8a98ea7c8cbca334b8 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -1752,6 +1752,7 @@ int mlx4_en_start_port(struct net_device *dev)
                                mlx4_en_arm_cq(priv, cq);
 
                        } else {
+                               mlx4_en_init_tx_xdp_ring_descs(priv, tx_ring);
                                mlx4_en_init_recycle_ring(priv, i);
                                /* XDP TX CQ should never be armed */
                        }

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index ac7254e3f9095e6e1543788fc42dc7423a0b4032..596445a4a241419737596b51fb38d00b02ad6681 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -1085,14 +1085,35 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 #define MLX4_EN_XDP_TX_REAL_SZ (((CTRL_SIZE + MLX4_EN_XDP_TX_NRTXBB * DS_SIZE) \
                                 / 16) & 0x3f)
 
+void mlx4_en_init_tx_xdp_ring_descs(struct mlx4_en_priv *priv,
+                                   struct mlx4_en_tx_ring *ring)
+{
+       int i;
+
+       for (i = 0; i < ring->size; i++) {
+               struct mlx4_en_tx_info *tx_info = &ring->tx_info[i];
+               struct mlx4_en_tx_desc *tx_desc = ring->buf +
+                       (i << LOG_TXBB_SIZE);
+
+               tx_info->map0_byte_count = PAGE_SIZE;
+               tx_info->nr_txbb = MLX4_EN_XDP_TX_NRTXBB;
+               tx_info->data_offset = offsetof(struct mlx4_en_tx_desc, data);
+               tx_info->ts_requested = 0;
+               tx_info->nr_maps = 1;
+               tx_info->linear = 1;
+               tx_info->inl = 0;
+
+               tx_desc->data.lkey = ring->mr_key;
+               tx_desc->ctrl.qpn_vlan.fence_size = MLX4_EN_XDP_TX_REAL_SZ;
+               tx_desc->ctrl.srcrb_flags = priv->ctrl_flags;
+       }
+}
+
 netdev_tx_t mlx4_en_xmit_frame(struct mlx4_en_rx_ring *rx_ring,
                               struct mlx4_en_rx_alloc *frame,
                               struct mlx4_en_priv *priv, unsigned int length,
                               int tx_ind, bool *doorbell_pending)
 {
-       union mlx4_wqe_qpn_vlan qpn_vlan = {
-               .fence_size = MLX4_EN_XDP_TX_REAL_SZ,
-       };
        struct mlx4_en_tx_desc *tx_desc;
        struct mlx4_en_tx_info *tx_info;
        struct mlx4_wqe_data_seg *data;
@@ -1124,20 +1145,12 @@ netdev_tx_t mlx4_en_xmit_frame(struct mlx4_en_rx_ring *rx_ring,
        tx_info->page = frame->page;
        frame->page = NULL;
        tx_info->map0_dma = dma;
-       tx_info->map0_byte_count = PAGE_SIZE;
-       tx_info->nr_txbb = MLX4_EN_XDP_TX_NRTXBB;
        tx_info->nr_bytes = max_t(unsigned int, length, ETH_ZLEN);
-       tx_info->data_offset = offsetof(struct mlx4_en_tx_desc, data);
-       tx_info->ts_requested = 0;
-       tx_info->nr_maps = 1;
-       tx_info->linear = 1;
-       tx_info->inl = 0;
 
        dma_sync_single_range_for_device(priv->ddev, dma, frame->page_offset,
                                         length, PCI_DMA_TODEVICE);
 
        data->addr = cpu_to_be64(dma + frame->page_offset);
-       data->lkey = ring->mr_key;
        dma_wmb();
        data->byte_count = cpu_to_be32(length);
 
@@ -1152,9 +1165,6 @@ netdev_tx_t mlx4_en_xmit_frame(struct mlx4_en_rx_ring *rx_ring,
 
        ring->prod += MLX4_EN_XDP_TX_NRTXBB;
 
-       tx_desc->ctrl.qpn_vlan = qpn_vlan;
-       tx_desc->ctrl.srcrb_flags = priv->ctrl_flags;
-
        /* Ensure new descriptor hits memory
         * before setting ownership of this descriptor to HW
         */

diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index 8cad9b4f1936e7ffd6092c6a88e095ab725149c1..1856e279a7e0a40b9365da2016a1b52e9156479b 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -705,6 +705,8 @@ int mlx4_en_create_tx_ring(struct mlx4_en_priv *priv,
                           int node, int queue_index);
 void mlx4_en_destroy_tx_ring(struct mlx4_en_priv *priv,
                             struct mlx4_en_tx_ring **pring);
+void mlx4_en_init_tx_xdp_ring_descs(struct mlx4_en_priv *priv,
+                                   struct mlx4_en_tx_ring *ring);
 int mlx4_en_activate_tx_ring(struct mlx4_en_priv *priv,
                             struct mlx4_en_tx_ring *ring,
                             int cq, int user_prio);