diff options
| author | Eric Dumazet <edumazet@google.com> | 2021-10-01 03:52:49 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-10-04 14:50:13 +0300 |
| commit | 9ac936276f8628ef5765bcc2ca7138a803de8aff (patch) | |
| tree | 0a1f9ee1782d8f9e51719971c9f168441a5cace8 /drivers/net/ethernet/mellanox/mlx4/en_tx.c | |
| parent | 0693b27644f04852e46f7f034e3143992b658869 (diff) | |
| download | linux-9ac936276f8628ef5765bcc2ca7138a803de8aff.tar.xz | |
net/mlx4_en: avoid one cache line miss to ring doorbell
This patch caches doorbell address directly in struct mlx4_en_tx_ring.
This removes the need to bring in cpu caches whole struct mlx4_uar
in fast path.
Note that mlx4_uar is not guaranteed to be on a local node,
because mlx4_bf_alloc() uses a single free list (priv->bf_list)
regardless of its node parameter.
This kind of change does matter in presence of light/moderate traffic.
In high stress, this read-only line would be kept hot in caches.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/mellanox/mlx4/en_tx.c')
| -rw-r--r-- | drivers/net/ethernet/mellanox/mlx4/en_tx.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c index c56b9dba4c71..817f4154b86d 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c @@ -130,6 +130,7 @@ int mlx4_en_create_tx_ring(struct mlx4_en_priv *priv, ring->bf_enabled = !!(priv->pflags & MLX4_EN_PRIV_FLAGS_BLUEFLAME); } + ring->doorbell_address = ring->bf.uar->map + MLX4_SEND_DOORBELL; ring->hwtstamp_tx_type = priv->hwtstamp_config.tx_type; ring->queue_index = queue_index; @@ -753,8 +754,7 @@ void mlx4_en_xmit_doorbell(struct mlx4_en_tx_ring *ring) #else iowrite32be( #endif - (__force u32)ring->doorbell_qpn, - ring->bf.uar->map + MLX4_SEND_DOORBELL); + (__force u32)ring->doorbell_qpn, ring->doorbell_address); } static void mlx4_en_tx_write_desc(struct mlx4_en_tx_ring *ring, |