net/mlx5e: Enable adaptive-TX moderation

Add support for adaptive TX moderation. This greatly reduces TX interrupt
rate and increases bandwidth, mostly for TCP bandwidth over ARM
architecture (below). There is a slight single stream TCP with very large
message sizes degradation (x86). In this case if there's any moderation on
transmitted packets the bandwidth would reduce due to hitting TCP output limit.
Since this is a synthetic case, this is still worth doing.

Performance improvement (ConnectX-4Lx 40GbE, ARM)
TCP 64B bandwidth with 1-50 streams increased 6-35%.
TCP 64B bandwidth with 100-500 streams increased 20-70%.

Performance improvement (ConnectX-5 100GbE, x86)
Bandwidth: increased up to 40% (1024B with 10s of streams).
Interrupt rate: reduced up to 50% (1024B with 1000s of streams).

Performance degradation (ConnectX-5 100GbE, x86)
Bandwidth: up to 10% decrease single stream TCP (1MB message size from
51Gb/s to 47Gb/s).

Signed-off-by: Tal Gilboa <talgi@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 11 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index 37fd0245b6c1..2b786c4d3dab 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
@@ -389,14 +389,20 @@ static int mlx5e_set_channels(struct net_device *dev,
 int mlx5e_ethtool_get_coalesce(struct mlx5e_priv *priv,
 			       struct ethtool_coalesce *coal)
 {
+	struct net_dim_cq_moder *rx_moder, *tx_moder;
+
 	if (!MLX5_CAP_GEN(priv->mdev, cq_moderation))
 		return -EOPNOTSUPP;
 
-	coal->rx_coalesce_usecs       = priv->channels.params.rx_cq_moderation.usec;
-	coal->rx_max_coalesced_frames = priv->channels.params.rx_cq_moderation.pkts;
-	coal->tx_coalesce_usecs       = priv->channels.params.tx_cq_moderation.usec;
-	coal->tx_max_coalesced_frames = priv->channels.params.tx_cq_moderation.pkts;
-	coal->use_adaptive_rx_coalesce = priv->channels.params.rx_dim_enabled;
+	rx_moder = &priv->channels.params.rx_cq_moderation;
+	coal->rx_coalesce_usecs		= rx_moder->usec;
+	coal->rx_max_coalesced_frames	= rx_moder->pkts;
+	coal->use_adaptive_rx_coalesce	= priv->channels.params.rx_dim_enabled;
+
+	tx_moder = &priv->channels.params.tx_cq_moderation;
+	coal->tx_coalesce_usecs		= tx_moder->usec;
+	coal->tx_max_coalesced_frames	= tx_moder->pkts;
+	coal->use_adaptive_tx_coalesce	= priv->channels.params.tx_dim_enabled;
 
 	return 0;
 }
@@ -438,6 +444,7 @@ mlx5e_set_priv_channels_coalesce(struct mlx5e_priv *priv, struct ethtool_coalesc
 int mlx5e_ethtool_set_coalesce(struct mlx5e_priv *priv,
 			       struct ethtool_coalesce *coal)
 {
+	struct net_dim_cq_moder *rx_moder, *tx_moder;
 	struct mlx5_core_dev *mdev = priv->mdev;
 	struct mlx5e_channels new_channels = {};
 	int err = 0;
@@ -463,11 +470,15 @@ int mlx5e_ethtool_set_coalesce(struct mlx5e_priv *priv,
 	mutex_lock(&priv->state_lock);
 	new_channels.params = priv->channels.params;
 
-	new_channels.params.tx_cq_moderation.usec = coal->tx_coalesce_usecs;
-	new_channels.params.tx_cq_moderation.pkts = coal->tx_max_coalesced_frames;
-	new_channels.params.rx_cq_moderation.usec = coal->rx_coalesce_usecs;
-	new_channels.params.rx_cq_moderation.pkts = coal->rx_max_coalesced_frames;
-	new_channels.params.rx_dim_enabled        = !!coal->use_adaptive_rx_coalesce;
+	rx_moder          = &new_channels.params.rx_cq_moderation;
+	rx_moder->usec    = coal->rx_coalesce_usecs;
+	rx_moder->pkts    = coal->rx_max_coalesced_frames;
+	new_channels.params.rx_dim_enabled = !!coal->use_adaptive_rx_coalesce;
+
+	tx_moder          = &new_channels.params.tx_cq_moderation;
+	tx_moder->usec    = coal->tx_coalesce_usecs;
+	tx_moder->pkts    = coal->tx_max_coalesced_frames;
+	new_channels.params.tx_dim_enabled = !!coal->use_adaptive_tx_coalesce;
 
 	if (!test_bit(MLX5E_STATE_OPENED, &priv->state)) {
 		priv->channels.params = new_channels.params;
@@ -475,7 +486,9 @@ int mlx5e_ethtool_set_coalesce(struct mlx5e_priv *priv,
 	}
 	/* we are opened */
 
-	reset = !!coal->use_adaptive_rx_coalesce != priv->channels.params.rx_dim_enabled;
+	reset = (!!coal->use_adaptive_rx_coalesce != priv->channels.params.rx_dim_enabled) ||
+		(!!coal->use_adaptive_tx_coalesce != priv->channels.params.tx_dim_enabled);
+
 	if (!reset) {
 		mlx5e_set_priv_channels_coalesce(priv, coal);
 		priv->channels.params = new_channels.params;