From fbc6daf19745b372c0d909e5d74ab02e42b70e51 Mon Sep 17 00:00:00 2001 From: Amir Vadai Date: Tue, 8 Jul 2014 11:28:12 +0300 Subject: [PATCH] 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 Signed-off-by: Amir Vadai Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlx4/en_ethtool.c | 7 +++++++ drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 1 + drivers/net/ethernet/mellanox/mlx4/en_tx.c | 28 ++++++++++++------------- drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 3 +++ 4 files changed, 24 insertions(+), 15 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c index fa1a069..68d763d 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c @@ -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); } diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c index e94d96f..7345c43 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c @@ -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); diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c index ac3dead..5045bab 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c @@ -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; + napi_complete(napi); + mlx4_en_arm_cq(priv, cq); + + return 0; } static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv, diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h index 624e193..d72a5a8 100644 --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h @@ -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; -- 2.7.4