From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net-next] mlx4: change TX coalescing defaults Date: Mon, 05 Nov 2012 18:20:42 -0800 Message-ID: <1352168442.3140.32.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev , Yevgeny Petrilin , Or Gerlitz , Vimalkumar To: David Miller Return-path: Received: from mail-pa0-f46.google.com ([209.85.220.46]:40196 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933594Ab2KFCUp (ORCPT ); Mon, 5 Nov 2012 21:20:45 -0500 Received: by mail-pa0-f46.google.com with SMTP id hz1so4380264pad.19 for ; Mon, 05 Nov 2012 18:20:44 -0800 (PST) Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet 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 Signed-off-by: Eric Dumazet Cc: Yevgeny Petrilin Cc: Or Gerlitz --- By the way, is BQL addition planned for this driver ? drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 2 +- drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c index edd9cb8..2b23ca2 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c @@ -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; 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 @@ 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