netdev - Re: [PATCH net-next] net: netdev_alloc_skb() use build

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Message-ID: <20120517174551.GN14498@1wt.eu>
Date:	Thu, 17 May 2012 19:45:51 +0200
From:	Willy Tarreau <w@....eu>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()

On Thu, May 17, 2012 at 07:34:16PM +0200, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> Please note I havent tested yet this patch, lacking hardware for this.
> 
> (tg3/bnx2/bnx2x use build_skb, r8169 does a copy of incoming frames,
> ixgbe uses fragments...)
> 
> Any volunteer ?
> 
> Thanks
> 
> [PATCH net-next] net: netdev_alloc_skb() use build_skb()
> 
> netdev_alloc_skb() is used by networks driver in their RX path to
> allocate an skb to receive an incoming frame.
> 
> With recent skb->head_frag infrastructure, it makes sense to change
> netdev_alloc_skb() to use build_skb() and a frag allocator.
> 
> This permits a zero copy splice(socket->pipe), and better GRO or TCP
> coalescing.

Impressed !

For the first time I could proxy HTTP traffic at gigabit speed on this
little box powered by USB ! I've long believed that proper splicing
would make this possible and now I'm seeing it is. Congrats Eric !

I'm still observing some stalls on medium-sized files (eg: 100k,
smaller than the pipe size, don't know yet if there is any relation).
I'll check closer and try to report something more exploitable.

Cheers,
Willy

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