From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH net-next 03/11] sfc: Increase size of RX SKB header area
Date: Wed, 19 Jun 2013 15:38:20 -0700
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Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org,
	linux-net-drivers@solarflare.com
To: Ben Hutchings <bhutchings@solarflare.com>
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On Wed, 2013-06-19 at 23:18 +0100, Ben Hutchings wrote:
> From: Jon Cooper <jcooper@solarflare.com>
> 
> This allows the SKB to hold the headers without reallocation more often.
> 
> Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
> ---
>  drivers/net/ethernet/sfc/rx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
> index b915e09..6efff3d 100644
> --- a/drivers/net/ethernet/sfc/rx.c
> +++ b/drivers/net/ethernet/sfc/rx.c
> @@ -36,7 +36,7 @@
>  #define EFX_RECYCLE_RING_SIZE_NOIOMMU (2 * EFX_RX_PREFERRED_BATCH)
>  
>  /* Size of buffer allocated for skb header area. */
> -#define EFX_SKB_HEADERS  64u
> +#define EFX_SKB_HEADERS  128u
>  

Yes, TCP with timestamps needs 66 bytes of headers on IPv4, and more on
IPv6...