[PATCH RFC 06/11] net/mlx5e: Slightly reduce hardware LRO size


Saeed Mahameed <saeedm@...>
 

Before this patch LRO size was 64K, now with build_skb requires
extra room, headroom + sizeof(skb_shared_info) added to the data
buffer will make wqe size or page_frag_size slightly larger than
64K which will demand order 5 page instead of order 4 in 4K page systems.

We take those extra bytes from hardware LRO data size in order to not
increase the required page order for when hardware LRO is enabled.

Signed-off-by: Saeed Mahameed <saeedm@...>
---
drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 9f0f5f6..17f84f9 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -3185,8 +3185,11 @@ static void mlx5e_build_nic_netdev_priv(struct mlx5_core_dev *mdev,
mlx5e_build_default_indir_rqt(mdev, priv->params.indirection_rqt,
MLX5E_INDIR_RQT_SIZE, profile->max_nch(mdev));

- priv->params.lro_wqe_sz =
- MLX5E_PARAMS_DEFAULT_LRO_WQE_SZ;
+ priv->params.lro_wqe_sz =
+ MLX5E_PARAMS_DEFAULT_LRO_WQE_SZ -
+ /* Extra room needed for build_skb */
+ MLX5_RX_HEADROOM -
+ SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

/* Initialize pflags */
MLX5E_SET_PRIV_FLAG(priv, MLX5E_PFLAG_RX_CQE_BASED_MODER,
--
2.7.4