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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Or Gerlitz <or.gerlitz@gmail.com>
Cc: Shlomo Pongartz <shlomop@mellanox.com>,
	Rick Jones <rick.jones2@hp.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Tom Herbert <therbert@google.com>
Subject: Re: GRO aggregation
Date: Thu, 13 Sep 2012 14:34:31 +0200	[thread overview]
Message-ID: <1347539671.13103.1542.camel@edumazet-glaptop> (raw)
In-Reply-To: <1347537926.13103.1530.camel@edumazet-glaptop>

On Thu, 2012-09-13 at 14:05 +0200, Eric Dumazet wrote:

> But there is no real difference in throughput.
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> index 6c4f935..435c35e 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> @@ -96,8 +96,8 @@
>  /* Receive fragment sizes; we use at most 4 fragments (for 9600 byte MTU
>   * and 4K allocations) */
>  enum {
> -	FRAG_SZ0 = 512 - NET_IP_ALIGN,
> -	FRAG_SZ1 = 1024,
> +	FRAG_SZ0 = 1536 - NET_IP_ALIGN,
> +	FRAG_SZ1 = 2048,
>         FRAG_SZ2 = 4096,
>         FRAG_SZ3 = MLX4_EN_ALLOC_SIZE
>  };
> 

Oh well, adding one prefetch() is giving ~10% more throughput.

I guess this mlx4 driver needs some care.

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 5aba5ec..547eec8 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -38,6 +38,7 @@
 #include <linux/if_ether.h>
 #include <linux/if_vlan.h>
 #include <linux/vmalloc.h>
+#include <linux/prefetch.h>
 
 #include "mlx4_en.h"
 
@@ -617,7 +618,8 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
 		    !((dev->features & NETIF_F_LOOPBACK) ||
 		      priv->validate_loopback))
 			goto next;
-
+		/* avoid cache miss in tcp_gro_receive() */
+		prefetch((char *)ethh + 64);
 		/*
 		 * Packet is OK - process it.
 		 */

  reply	other threads:[~2012-09-13 12:34 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-11 13:45 GRO aggregation Shlomo Pongartz
2012-09-11 18:20 ` Marcelo Ricardo Leitner
2012-09-11 18:41   ` Shlomo Pongratz
2012-09-11 18:48     ` Marcelo Ricardo Leitner
2012-09-11 18:51       ` Shlomo Pongratz
2012-09-11 18:33 ` Eric Dumazet
2012-09-11 18:49   ` Shlomo Pongratz
2012-09-11 19:01     ` Eric Dumazet
2012-09-11 19:24       ` Shlomo Pongratz
2012-09-11 19:35         ` David Miller
2012-09-11 19:35         ` Eric Dumazet
2012-09-12  9:23           ` Shlomo Pongartz
2012-09-12  9:33             ` Eric Dumazet
2012-09-12 14:41               ` Shlomo Pongartz
2012-09-12 16:23                 ` Rick Jones
2012-09-12 16:34                   ` Shlomo Pongartz
2012-09-12 16:52                     ` Rick Jones
2012-09-13  6:36                       ` Shlomo Pongartz
2012-09-13  8:11                         ` Eric Dumazet
2012-09-13  9:59                           ` Or Gerlitz
2012-09-13 12:05                             ` Eric Dumazet
2012-09-13 12:34                               ` Eric Dumazet [this message]
2012-09-13 12:47                               ` Or Gerlitz
2012-09-13 13:22                                 ` Eric Dumazet

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