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Commit 6a4e8121 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net/mlx4_en: Avoid calling bswap in tx fast path 



- doorbell_qpn is stored in the cpu_to_be32() way to avoid bswap() in fast
  path.
- mdev->mr.key stored in ring->mr_key to also avoid bswap() and access to
  cold cache line.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarAmir Vadai <amirv@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 98b16349

drivers/net/ethernet/mellanox/mlx4/en_tx.c

+10 −7
Original line number Original line Diff line number Diff line
@@ -195,7 +195,8 @@ int mlx4_en_activate_tx_ring(struct mlx4_en_priv *priv, 
	memset(ring->buf, 0, ring->buf_size);

	memset(ring->buf, 0, ring->buf_size);





	ring->qp_state = MLX4_QP_STATE_RST;

	ring->qp_state = MLX4_QP_STATE_RST;

	ring->doorbell_qpn = ring->qp.qpn << 8;

	ring->doorbell_qpn = cpu_to_be32(ring->qp.qpn << 8);

	ring->mr_key = cpu_to_be32(mdev->mr.key);





	mlx4_en_fill_qp_context(priv, ring->size, ring->stride, 1, 0, ring->qpn,

	mlx4_en_fill_qp_context(priv, ring->size, ring->stride, 1, 0, ring->qpn,

				ring->cqn, user_prio, &ring->context);

				ring->cqn, user_prio, &ring->context);
@@ -654,7 +655,6 @@ static void mlx4_bf_copy(void __iomem *dst, const void *src, 
netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)

netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)

{

{

	struct mlx4_en_priv *priv = netdev_priv(dev);

	struct mlx4_en_priv *priv = netdev_priv(dev);

	struct mlx4_en_dev *mdev = priv->mdev;

	struct device *ddev = priv->ddev;

	struct device *ddev = priv->ddev;

	struct mlx4_en_tx_ring *ring;

	struct mlx4_en_tx_ring *ring;

	struct mlx4_en_tx_desc *tx_desc;

	struct mlx4_en_tx_desc *tx_desc;
@@ -769,7 +769,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) 
				goto tx_drop_unmap;

				goto tx_drop_unmap;





			data->addr = cpu_to_be64(dma);

			data->addr = cpu_to_be64(dma);

			data->lkey = cpu_to_be32(mdev->mr.key);

			data->lkey = ring->mr_key;

			wmb();

			wmb();

			data->byte_count = cpu_to_be32(skb_frag_size(frag));

			data->byte_count = cpu_to_be32(skb_frag_size(frag));

			--data;

			--data;
@@ -787,7 +787,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) 
				goto tx_drop_unmap;

				goto tx_drop_unmap;





			data->addr = cpu_to_be64(dma);

			data->addr = cpu_to_be64(dma);

			data->lkey = cpu_to_be32(mdev->mr.key);

			data->lkey = ring->mr_key;

			wmb();

			wmb();

			data->byte_count = cpu_to_be32(byte_count);

			data->byte_count = cpu_to_be32(byte_count);

		}

		}
@@ -879,9 +879,12 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) 




	send_doorbell = !skb->xmit_more || netif_xmit_stopped(ring->tx_queue);

	send_doorbell = !skb->xmit_more || netif_xmit_stopped(ring->tx_queue);





	real_size = (real_size / 16) & 0x3f;



	if (ring->bf_enabled && desc_size <= MAX_BF && !bounce &&

	if (ring->bf_enabled && desc_size <= MAX_BF && !bounce &&

	    !vlan_tx_tag_present(skb) && send_doorbell) {

	    !vlan_tx_tag_present(skb) && send_doorbell) {

		tx_desc->ctrl.bf_qpn |= cpu_to_be32(ring->doorbell_qpn);

		tx_desc->ctrl.bf_qpn = ring->doorbell_qpn |

				       cpu_to_be32(real_size);





		op_own |= htonl((bf_index & 0xffff) << 8);

		op_own |= htonl((bf_index & 0xffff) << 8);

		/* Ensure new descriptor hits memory

		/* Ensure new descriptor hits memory
@@ -911,7 +914,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) 
		tx_desc->ctrl.owner_opcode = op_own;

		tx_desc->ctrl.owner_opcode = op_own;

		if (send_doorbell) {

		if (send_doorbell) {

			wmb();

			wmb();

			iowrite32be(ring->doorbell_qpn,

			iowrite32(ring->doorbell_qpn,

				  ring->bf.uar->map + MLX4_SEND_DOORBELL);

				  ring->bf.uar->map + MLX4_SEND_DOORBELL);

		} else {

		} else {

			ring->xmit_more++;

			ring->xmit_more++;

drivers/net/ethernet/mellanox/mlx4/mlx4_en.h

+2 −1
Original line number Original line Diff line number Diff line
@@ -279,7 +279,8 @@ struct mlx4_en_tx_ring { 
	u16			stride;

	u16			stride;

	u16			cqn;	/* index of port CQ associated with this ring */

	u16			cqn;	/* index of port CQ associated with this ring */

	u32			buf_size;

	u32			buf_size;

	u32			doorbell_qpn;

	__be32			doorbell_qpn;

	__be32			mr_key;

	void			*buf;

	void			*buf;

	struct mlx4_en_tx_info	*tx_info;

	struct mlx4_en_tx_info	*tx_info;

	u8			*bounce_buf;

	u8			*bounce_buf;