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mlx4: change TX coalescing defaults 

mlx4 currently uses a too high tx coalescing setting, deferring
TX completion interrupts by up to 128 us.

With the recent skb_orphan() removal in commit 8112ec3b87,
performance of a single TCP flow is capped to ~4 Gbps, unless
we increase tcp_limit_output_bytes.

I suggest using 16 us instead of 128 us, allowing a finer control.

Performance of a single TCP flow is restored to previous levels,
while keeping TCP small queues fully enabled with default sysctl.

This patch is also a BQL prereq.

Reported-by: Vimalkumar <j.vimal@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yevgeny Petrilin <yevgenyp@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2012-11-05 16:20:42 +00:00 committed by David S. Miller
parent 6f0a0986e3
commit ecfd2ce1a9
2 changed files with 2 additions and 2 deletions
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2
drivers/net/ethernet/mellanox/mlx4/en_netdev.c
View File

@ -870,7 +870,7 @@ static void mlx4_en_set_default_moderation(struct mlx4_en_priv *priv)
/* If we haven't received a specific coalescing setting
* (module param), we set the moderation parameters as follows:
* - moder_cnt is set to the number of mtu sized packets to
* satisfy our coelsing target.
* satisfy our coalescing target.
* - moder_time is set to a fixed value.
*/
priv->rx_frames = MLX4_EN_RX_COAL_TARGET;

2
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
View File

@ -126,7 +126,7 @@ enum {
#define MLX4_EN_RX_COAL_TIME 0x10
#define MLX4_EN_TX_COAL_PKTS 16
#define MLX4_EN_TX_COAL_TIME 0x80
#define MLX4_EN_TX_COAL_TIME 0x10
#define MLX4_EN_RX_RATE_LOW 400000
#define MLX4_EN_RX_COAL_TIME_LOW 0