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Commit ecfd2ce1 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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 8112ec3b,
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: default avatarVimalkumar <j.vimal@gmail.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Yevgeny Petrilin <yevgenyp@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: default avatarAmir Vadai <amirv@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6f0a0986

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

+1 −1
Original line number Original line Diff line number Diff line
@@ -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

	/* If we haven't received a specific coalescing setting

	 * (module param), we set the moderation parameters as follows:

	 * (module param), we set the moderation parameters as follows:

	 * - moder_cnt is set to the number of mtu sized packets to

	 * - 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.

	 * - moder_time is set to a fixed value.

	 */

	 */

	priv->rx_frames = MLX4_EN_RX_COAL_TARGET;

	priv->rx_frames = MLX4_EN_RX_COAL_TARGET;

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

+1 −1
Original line number Original line Diff line number Diff line
@@ -126,7 +126,7 @@ enum { 
#define MLX4_EN_RX_COAL_TIME	0x10

#define MLX4_EN_RX_COAL_TIME	0x10





#define MLX4_EN_TX_COAL_PKTS	16

#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_RATE_LOW		400000

#define MLX4_EN_RX_COAL_TIME_LOW	0

#define MLX4_EN_RX_COAL_TIME_LOW	0