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Commit fbc6daf1 authored by Amir Vadai's avatar Amir Vadai Committed by David S. Miller
Browse files

net/mlx4_en: Ignore budget on TX napi polling 



It is recommended that TX work not count against the quota.
The cost of TX packet liberation is a minute percentage of what it costs to
process an RX frame. Furthermore, that SKB freeing makes memory available for
other paths in the stack.

Give the TX a larger budget and be more aggressive about cleaning up the Tx
descriptors this budget could be changed using ethtool:
$ ethtool -C eth1 tx-frames-irq <budget>

Signed-off-by: default avatarAmir Vadai <amirv@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0b030244

drivers/net/ethernet/mellanox/mlx4/en_ethtool.c

+7 −0
Original line number Diff line number Diff line
@@ -417,6 +417,8 @@ static int mlx4_en_get_coalesce(struct net_device *dev, 


	coal->tx_coalesce_usecs = priv->tx_usecs;

	coal->tx_max_coalesced_frames = priv->tx_frames;

	coal->tx_max_coalesced_frames_irq = priv->tx_work_limit;



	coal->rx_coalesce_usecs = priv->rx_usecs;

	coal->rx_max_coalesced_frames = priv->rx_frames;
@@ -426,6 +428,7 @@ static int mlx4_en_get_coalesce(struct net_device *dev, 
	coal->rx_coalesce_usecs_high = priv->rx_usecs_high;

	coal->rate_sample_interval = priv->sample_interval;

	coal->use_adaptive_rx_coalesce = priv->adaptive_rx_coal;



	return 0;

}
@@ -434,6 +437,9 @@ static int mlx4_en_set_coalesce(struct net_device *dev, 
{

	struct mlx4_en_priv *priv = netdev_priv(dev);



	if (!coal->tx_max_coalesced_frames_irq)

		return -EINVAL;



	priv->rx_frames = (coal->rx_max_coalesced_frames ==

			   MLX4_EN_AUTO_CONF) ?

				MLX4_EN_RX_COAL_TARGET :
@@ -457,6 +463,7 @@ static int mlx4_en_set_coalesce(struct net_device *dev, 
	priv->rx_usecs_high = coal->rx_coalesce_usecs_high;

	priv->sample_interval = coal->rate_sample_interval;

	priv->adaptive_rx_coal = coal->use_adaptive_rx_coalesce;

	priv->tx_work_limit = coal->tx_max_coalesced_frames_irq;



	return mlx4_en_moderation_update(priv);

}

drivers/net/ethernet/mellanox/mlx4/en_netdev.c

+1 −0
Original line number Diff line number Diff line
@@ -2473,6 +2473,7 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port, 
			MLX4_WQE_CTRL_SOLICITED);

	priv->num_tx_rings_p_up = mdev->profile.num_tx_rings_p_up;

	priv->tx_ring_num = prof->tx_ring_num;

	priv->tx_work_limit = MLX4_EN_DEFAULT_TX_WORK;



	priv->tx_ring = kzalloc(sizeof(struct mlx4_en_tx_ring *) * MAX_TX_RINGS,

				GFP_KERNEL);

drivers/net/ethernet/mellanox/mlx4/en_tx.c

+13 −15
Original line number Diff line number Diff line
@@ -351,9 +351,8 @@ int mlx4_en_free_tx_buf(struct net_device *dev, struct mlx4_en_tx_ring *ring) 
	return cnt;

}



static int mlx4_en_process_tx_cq(struct net_device *dev,

				 struct mlx4_en_cq *cq,

				 int budget)

static bool mlx4_en_process_tx_cq(struct net_device *dev,

				 struct mlx4_en_cq *cq)

{

	struct mlx4_en_priv *priv = netdev_priv(dev);

	struct mlx4_cq *mcq = &cq->mcq;
@@ -372,9 +371,10 @@ static int mlx4_en_process_tx_cq(struct net_device *dev, 
	int factor = priv->cqe_factor;

	u64 timestamp = 0;

	int done = 0;

	int budget = priv->tx_work_limit;



	if (!priv->port_up)

		return 0;

		return true;



	index = cons_index & size_mask;

	cqe = &buf[(index << factor) + factor];
@@ -447,7 +447,7 @@ static int mlx4_en_process_tx_cq(struct net_device *dev, 
		netif_tx_wake_queue(ring->tx_queue);

		ring->wake_queue++;

	}

	return done;

	return done < budget;

}



void mlx4_en_tx_irq(struct mlx4_cq *mcq)
@@ -467,18 +467,16 @@ int mlx4_en_poll_tx_cq(struct napi_struct *napi, int budget) 
	struct mlx4_en_cq *cq = container_of(napi, struct mlx4_en_cq, napi);

	struct net_device *dev = cq->dev;

	struct mlx4_en_priv *priv = netdev_priv(dev);

	int done;

	int clean_complete;



	done = mlx4_en_process_tx_cq(dev, cq, budget);

	clean_complete = mlx4_en_process_tx_cq(dev, cq);

	if (!clean_complete)

		return budget;



	/* If we used up all the quota - we're probably not done yet... */

	if (done < budget) {

		/* Done for now */

	napi_complete(napi);

	mlx4_en_arm_cq(priv, cq);

		return done;

	}

	return budget;



	return 0;

}



static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv,

drivers/net/ethernet/mellanox/mlx4/mlx4_en.h

+3 −0
Original line number Diff line number Diff line
@@ -126,6 +126,8 @@ enum { 
#define MAX_TX_RINGS			(MLX4_EN_MAX_TX_RING_P_UP * \

					 MLX4_EN_NUM_UP)



#define MLX4_EN_DEFAULT_TX_WORK		256



/* Target number of packets to coalesce with interrupt moderation */

#define MLX4_EN_RX_COAL_TARGET	44

#define MLX4_EN_RX_COAL_TIME	0x10
@@ -543,6 +545,7 @@ struct mlx4_en_priv { 
	__be32 ctrl_flags;

	u32 flags;

	u8 num_tx_rings_p_up;

	u32 tx_work_limit;

	u32 tx_ring_num;

	u32 rx_ring_num;

	u32 rx_skb_size;