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Date: Tue, 8 Jul 2014 11:28:12 +0300
From: Amir Vadai <amirv@...lanox.com>
To: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>
Cc: netdev@...r.kernel.org, Yevgeny Petrilin <yevgenyp@...lanox.com>,
Or Gerlitz <ogerlitz@...lanox.com>,
Amir Vadai <amirv@...lanox.com>
Subject: [PATCH net] 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: Amir Vadai <amirv@...lanox.com>
---
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 7d4fb7b..f451382 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;
--
1.8.3.4
--
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