tree ae9078f61e390a3014aecb3fe80d3438ab25ee51
parent eae3f29cc73f83cc3f1891d3ad40021b5172c630
author Eric Dumazet <eric.dumazet@gmail.com> 1244174656 +0000
committer David S. Miller <davem@davemloft.net> 1244445708 -0700

net: skb_shared_info optimization

skb_dma_unmap() is quite expensive for small packets,
because we use two different cache lines from skb_shared_info.

One to access nr_frags, one to access dma_maps[0]

Instead of dma_maps being an array of MAX_SKB_FRAGS + 1 elements,
let dma_head alone in a new dma_head field, close to nr_frags,
to reduce cache lines misses.

Tested on my dev machine (bnx2 & tg3 adapters), nice speedup !

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>