diff options
| author | Eric Dumazet <edumazet@google.com> | 2014-09-25 07:17:49 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-09-28 17:27:36 -0400 |
| commit | 5804283d7cb1da46485950d545dd7869137dcda5 (patch) | |
| tree | ba4656cb940b502838058edbf81d15cf147d0171 | |
| parent | a8404ce5ae7a6054322afb5aa77cefe3ad54475e (diff) | |
| download | linux-5804283d7cb1da46485950d545dd7869137dcda5.tar.bz2 | |
mlx4: exploit skb->xmit_more to conditionally send doorbell
skb->xmit_more tells us if another skb is coming next.
We need to send doorbell when : xmit_more is not set,
or txqueue is stopped (preventing next skb to come immediately)
Tested with a modified pktgen version, I got a 40% increase of
throughput.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/ethernet/mellanox/mlx4/en_tx.c | 23 |
1 files changed, 16 insertions, 7 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c index c44f4237b9be..adedc47e947d 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c @@ -667,6 +667,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) int lso_header_size; void *fragptr; bool bounce = false; + bool send_doorbell; if (!priv->port_up) goto tx_drop; @@ -878,12 +879,16 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) skb_tx_timestamp(skb); - if (ring->bf_enabled && desc_size <= MAX_BF && !bounce && !vlan_tx_tag_present(skb)) { + send_doorbell = !skb->xmit_more || netif_xmit_stopped(ring->tx_queue); + + if (ring->bf_enabled && desc_size <= MAX_BF && !bounce && + !vlan_tx_tag_present(skb) && send_doorbell) { tx_desc->ctrl.bf_qpn |= cpu_to_be32(ring->doorbell_qpn); op_own |= htonl((bf_index & 0xffff) << 8); - /* Ensure new descirptor hits memory - * before setting ownership of this descriptor to HW */ + /* Ensure new descriptor hits memory + * before setting ownership of this descriptor to HW + */ wmb(); tx_desc->ctrl.owner_opcode = op_own; @@ -896,12 +901,16 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) ring->bf.offset ^= ring->bf.buf_size; } else { - /* Ensure new descirptor hits memory - * before setting ownership of this descriptor to HW */ + /* Ensure new descriptor hits memory + * before setting ownership of this descriptor to HW + */ wmb(); tx_desc->ctrl.owner_opcode = op_own; - wmb(); - iowrite32be(ring->doorbell_qpn, ring->bf.uar->map + MLX4_SEND_DOORBELL); + if (send_doorbell) { + wmb(); + iowrite32be(ring->doorbell_qpn, + ring->bf.uar->map + MLX4_SEND_DOORBELL); + } } return NETDEV_TX_OK; |