netdev - [net-next 02/15] net/mlx5e: Disable Striding RQ when PCI is slower than link

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Date:   Tue, 27 Mar 2018 17:42:36 -0700
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net-next 02/15] net/mlx5e: Disable Striding RQ when PCI is slower than link

From: Tariq Toukan <tariqt@...lanox.com>

We turn the feature off for servers with PCI BW bounded
by a threshold (16G) and lower than MAX LINK BW.
This improves the effectiveness of CQE compression feature,
that is defaulted to ON for the same case.

Signed-off-by: Tariq Toukan <tariqt@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 46707826f27e..d4dd00089eb1 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -113,13 +113,16 @@ void mlx5e_init_rq_type_params(struct mlx5_core_dev *mdev,
 		       MLX5E_GET_PFLAG(params, MLX5E_PFLAG_RX_CQE_COMPRESS));
 }
 
+static bool slow_pci_heuristic(struct mlx5_core_dev *mdev);
+
 static void mlx5e_set_rq_params(struct mlx5_core_dev *mdev,
 				struct mlx5e_params *params)
 {
 	u8 rq_type = mlx5e_check_fragmented_striding_rq_cap(mdev) &&
-		    !params->xdp_prog && !MLX5_IPSEC_DEV(mdev) ?
-		    MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ :
-		    MLX5_WQ_TYPE_LINKED_LIST;
+		!slow_pci_heuristic(mdev) &&
+		!params->xdp_prog && !MLX5_IPSEC_DEV(mdev) ?
+		MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ :
+		MLX5_WQ_TYPE_LINKED_LIST;
 	mlx5e_init_rq_type_params(mdev, params, rq_type);
 }
 
-- 
2.14.3