diff options
| author |   Eric Dumazet <edumazet@google.com> | 2021-09-30 17:52:49 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2021-10-04 12:50:13 +0100 |
| commit | 9ac936276f8628ef5765bcc2ca7138a803de8aff (patch) | |
| tree | 0a1f9ee1782d8f9e51719971c9f168441a5cace8 /drivers/net/ethernet/mellanox | |
| parent | Merge branch 'mctp-kunit-tests' (diff) | |
| download | linux-dev-9ac936276f8628ef5765bcc2ca7138a803de8aff.tar.xz linux-dev-9ac936276f8628ef5765bcc2ca7138a803de8aff.zip | |
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')
| -rw-r--r-- | drivers/net/ethernet/mellanox/mlx4/en_tx.c | 4 | ||||
| -rw-r--r-- | drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 1 |
2 files changed, 3 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, diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h index ad0a8b488832..e132ff4c82f2 100644 --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h @@ -283,6 +283,7 @@ struct mlx4_en_tx_ring { struct mlx4_bf bf; /* Following part should be mostly read */ + void __iomem *doorbell_address; __be32 doorbell_qpn; __be32 mr_key; u32 size; /* number of TXBBs */ |