net/mlx5e: Disable HW LRO when PCI is slower than link on striding RQ

We will activate the HW LRO only on servers with PCI BW > MAX LINK BW,
or when PCI BW > 16Gbps. On other cases we do not want LRO by default as
LRO sessions might get timeout and add redundant software overhead.

Tested:
	ethtool -k <ifs-name> | grep large-receive-offload
	On systems with and without the limitations.

Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Cc: kernel-team@fb.com
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 1afaca9..a61b71b 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -3785,6 +3785,12 @@ static bool cqe_compress_heuristic(u32 link_speed, u32 pci_bw)
                (pci_bw < 40000) && (pci_bw < link_speed));
 }
 
+static bool hw_lro_heuristic(u32 link_speed, u32 pci_bw)
+{
+       return !(link_speed && pci_bw &&
+                (pci_bw <= 16000) && (pci_bw < link_speed));
+}
+
 void mlx5e_set_rx_cq_mode_params(struct mlx5e_params *params, u8 cq_period_mode)
 {
        params->rx_cq_period_mode = cq_period_mode;
@@ -3829,6 +3835,11 @@ void mlx5e_build_nic_params(struct mlx5_core_dev *mdev,
        params->num_channels = max_channels;
        params->num_tc       = 1;
 
+       mlx5e_get_max_linkspeed(mdev, &link_speed);
+       mlx5e_get_pci_bw(mdev, &pci_bw);
+       mlx5_core_dbg(mdev, "Max link speed = %d, PCI BW = %d\n",
+                     link_speed, pci_bw);
+
        /* SQ */
        params->log_sq_size = is_kdump_kernel() ?
                MLX5E_PARAMS_MINIMUM_LOG_SQ_SIZE :
@@ -3837,13 +3848,9 @@ void mlx5e_build_nic_params(struct mlx5_core_dev *mdev,
        /* set CQE compression */
        params->rx_cqe_compress_def = false;
        if (MLX5_CAP_GEN(mdev, cqe_compression) &&
-            MLX5_CAP_GEN(mdev, vport_group_manager)) {
-               mlx5e_get_max_linkspeed(mdev, &link_speed);
-               mlx5e_get_pci_bw(mdev, &pci_bw);
-               mlx5_core_dbg(mdev, "Max link speed = %d, PCI BW = %d\n",
-                              link_speed, pci_bw);
+            MLX5_CAP_GEN(mdev, vport_group_manager))
                params->rx_cqe_compress_def = cqe_compress_heuristic(link_speed, pci_bw);
-       }
+
        MLX5E_SET_PFLAG(params, MLX5E_PFLAG_RX_CQE_COMPRESS, params->rx_cqe_compress_def);
 
        /* RQ */
@@ -3852,7 +3859,7 @@ void mlx5e_build_nic_params(struct mlx5_core_dev *mdev,
        /* HW LRO */
        /* TODO: && MLX5_CAP_ETH(mdev, lro_cap) */
        if (params->rq_wq_type == MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ)
-               params->lro_en = true;
+               params->lro_en = hw_lro_heuristic(link_speed, pci_bw);
        params->lro_timeout = mlx5e_choose_lro_timeout(mdev, MLX5E_DEFAULT_LRO_TIMEOUT);
 
        /* CQ moderation params */