Re: [PATCH net-next-2.6] net: replace hooks in __netif_receive_skb V3

[Eric Dumazet <eric.dumazet@gmail.com>]

Le vendredi 28 mai 2010 à 08:12 +0200, Jiri Pirko a écrit :

> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index a1bff65..f54b97d 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -254,6 +254,16 @@ struct netdev_hw_addr_list {
>  #define netdev_for_each_mc_addr(ha, dev) \
>  	netdev_hw_addr_list_for_each(ha, &(dev)->mc)
>  
> +
> +struct netdev_rx_handler {
> +	struct list_head	list;
> +	unsigned int		order;
> +#define NETDEV_RX_HANDLER_ORDER_BRIDGE	1
> +#define NETDEV_RX_HANDLER_ORDER_MACVLAN	2
> +	struct sk_buff		*(*callback)(struct sk_buff *skb);
> +	struct rcu_head		rcu;
> +};
> +
>  struct hh_cache {
>  	struct hh_cache *hh_next;	/* Next entry			     */
>  	atomic_t	hh_refcnt;	/* number of users                   */
> @@ -1031,6 +1041,9 @@ struct net_device {
>  	/* GARP */
>  	struct garp_port	*garp_port;
>  
> +	/* receive handlers (hooks) list */
> +	struct list_head	rx_handlers;
> +
>  	/* class/net/name entry */
>  	struct device		dev;
>  	/* space for optional device, statistics, and wireless sysfs groups */
> @@ -1685,6 +1698,11 @@ static inline void napi_free_frags(struct napi_struct *napi)
>  	napi->skb = NULL;
>  }
>  

Please chose another place to hold rx_handlers, to keep rx path memory
needs to minimum cache lines. Somewhere in the following section :

/*
 * Cache line mostly used on receive path (including eth_type_trans())
 */
        unsigned long           last_rx;        /* Time of last Rx      */
        /* Interface address info used in eth_type_trans() */
        unsigned char           *dev_addr;      /* hw address, (before bcast
                                                   because most packets are
                                                   unicast) */

        struct netdev_hw_addr_list      dev_addrs; /* list of device
                                                      hw addresses */

        unsigned char           broadcast[MAX_ADDR_LEN];        /* hw bcast add */

#ifdef CONFIG_RPS
        struct kset             *queues_kset;

        struct netdev_rx_queue  *_rx;

        /* Number of RX queues allocated at alloc_netdev_mq() time  */
        unsigned int            num_rx_queues;
#endif

        struct netdev_queue     rx_queue;


and before the :

	struct netdev_queue     *_tx ____cacheline_aligned_in_smp;