On Fri, 2013-05-17 at 15:50 +0900, Simon Horman wrote:
> @@ -509,6 +511,8 @@ struct sk_buff {
> __u32 reserved_tailroom;
> };
>
> + __be16 inner_protocol;
> + /* 16/48 bit hole */
> sk_buff_data_t inner_transport_header;
> sk_buff_data_t inner_network_header;
> sk_buff_data_t inner_mac_header;
We are reaching the point where sk_buff is so big that per packet cost
is killing us, and guys want linux kernel bypass.
sizeof(sk_buff) = 0xf8 -> 0x100
sizeof(skbuff_fclone_cache) = 0x200 -> 0x240
So TCP stack performance is going to be hurt by this change, as the
atomic_t containing fclone_ref will be in a separate cache line.
__copy_skb_header() needs to be smarter and perform a bulk copy using
long words
Maybe we could use 16 bits instead of 32 for the inner_*_headers ?
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