diff options
| author | Eric Dumazet <edumazet@google.com> | 2014-10-05 12:35:16 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-10-06 01:04:15 -0400 |
| commit | f905c79e12791d09bbfd9ba7b672fbeb19c1e7c2 (patch) | |
| tree | e541f28def46a232650e1117c66c129d1f086fe9 | |
| parent | fb1843ee72c7b2ed784bf88ad79c6ccc2f652499 (diff) | |
net/mlx4_en: mlx4_en_xmit() reads ring->cons once, and ahead of time to avoid stalls
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/ethernet/mellanox/mlx4/en_tx.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c index d9aaeb2d019f..99875c8d70c1 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c @@ -691,10 +691,17 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) void *fragptr; bool bounce = false; bool send_doorbell; + u32 ring_cons; if (!priv->port_up) goto tx_drop; + tx_ind = skb_get_queue_mapping(skb); + ring = priv->tx_ring[tx_ind]; + + /* fetch ring->cons far ahead before needing it to avoid stall */ + ring_cons = ACCESS_ONCE(ring->cons); + real_size = get_real_size(skb, dev, &lso_header_size); if (unlikely(!real_size)) goto tx_drop; @@ -708,13 +715,11 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) goto tx_drop; } - tx_ind = skb->queue_mapping; - ring = priv->tx_ring[tx_ind]; if (vlan_tx_tag_present(skb)) vlan_tag = vlan_tx_tag_get(skb); /* Check available TXBBs And 2K spare for prefetch */ - if (unlikely(((int)(ring->prod - ring->cons)) > + if (unlikely(((int)(ring->prod - ring_cons)) > ring->size - HEADROOM - MAX_DESC_TXBBS)) { /* every full Tx ring stops queue */ netif_tx_stop_queue(ring->tx_queue); @@ -728,7 +733,8 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) */ wmb(); - if (unlikely(((int)(ring->prod - ring->cons)) <= + ring_cons = ACCESS_ONCE(ring->cons); + if (unlikely(((int)(ring->prod - ring_cons)) <= ring->size - HEADROOM - MAX_DESC_TXBBS)) { netif_tx_wake_queue(ring->tx_queue); ring->wake_queue++; @@ -741,7 +747,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) /* Track current inflight packets for performance analysis */ AVG_PERF_COUNTER(priv->pstats.inflight_avg, - (u32) (ring->prod - ring->cons - 1)); + (u32)(ring->prod - ring_cons - 1)); /* Packet is good - grab an index and transmit it */ index = ring->prod & ring->size_mask; |