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    SubjectRe: [PATCH ref0] net: add Faraday FTMAC100 10/100 Ethernet driver
    Hi Eric,

    On Fri, Feb 25, 2011 at 1:48 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
    > Le jeudi 24 février 2011 à 18:39 +0100, Eric Dumazet a écrit :
    >> Le jeudi 24 février 2011 à 17:29 +0800, Po-Yu Chuang a écrit :
    >> > From: Po-Yu Chuang <ratbert@faraday-tech.com>
    >> > +
    >> > +static bool ftmac100_rx_packet(struct ftmac100 *priv, int *processed)
    >> > +{
    >> > +   struct net_device *netdev = priv->netdev;
    >> > +   struct ftmac100_rxdes *rxdes;
    >> > +   struct sk_buff *skb;
    >> > +   struct page *page;
    >> > +   dma_addr_t map;
    >> > +   int length;
    >> > +
    >> > +   rxdes = ftmac100_rx_locate_first_segment(priv);
    >> > +   if (!rxdes)
    >> > +           return false;
    >> > +
    >> > +   if (unlikely(ftmac100_rx_packet_error(priv, rxdes))) {
    >> > +           ftmac100_rx_drop_packet(priv);
    >> > +           return true;
    >> > +   }
    >> > +
    >> > +   /*
    >> > +    * It is impossible to get multi-segment packets
    >> > +    * because we always provide big enough receive buffers.
    >> > +    */
    >> > +   if (unlikely(!ftmac100_rxdes_last_segment(rxdes)))
    >> > +           BUG();
    >> > +
    >> > +   /* start processing */
    >> > +   skb = netdev_alloc_skb_ip_align(netdev, ETH_HLEN);
    >>
    >> Oh I see... You should allocate a bigger head (say... 128 bytes)
    >>
    >> And copy in it up to 128 bytes of first part... this to avoid upper
    >> stack to reallocate skb head (because IP/TCP processing need to get
    >> their headers in skb head)
    >
    > Take a look at drivers/net/niu.c :
    >
    > #define RX_SKB_ALLOC_SIZE   128 + NET_IP_ALIGN
    >
    > static int niu_process_rx_pkt(...)
    > {
    >        ...
    >        skb = netdev_alloc_skb(np->dev, RX_SKB_ALLOC_SIZE);
    >        ...
    >        while (1) {
    >                ...
    >                niu_rx_skb_append(skb, page, off, append_size);
    >        }
    > }

    Oh I got it.

    I will try this and redo the benchmarking.

    Thanks,
    Po-Yu Chuang
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