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 8112ec3b872,
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>
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index 9d27e42..8a5e70d 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -126,7 +126,7 @@
#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