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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2009-06-05 08:04:16 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-06-08 11:21:48 +0400 |
| commit | 042a53a9e437feaf2230dd2cadcecfae9c7bfe05 (patch) | |
| tree | ae9078f61e390a3014aecb3fe80d3438ab25ee51 /include/linux/skbuff.h | |
| parent | eae3f29cc73f83cc3f1891d3ad40021b5172c630 (diff) | |
| download | linux-042a53a9e437feaf2230dd2cadcecfae9c7bfe05.tar.xz | |
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>
Diffstat (limited to 'include/linux/skbuff.h')
| -rw-r--r-- | include/linux/skbuff.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 7485058125e3..aad484cd5863 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -189,6 +189,9 @@ struct skb_shared_info { atomic_t dataref; unsigned short nr_frags; unsigned short gso_size; +#ifdef CONFIG_HAS_DMA + dma_addr_t dma_head; +#endif /* Warning: this field is not always filled in (UFO)! */ unsigned short gso_segs; unsigned short gso_type; @@ -198,7 +201,7 @@ struct skb_shared_info { struct skb_shared_hwtstamps hwtstamps; skb_frag_t frags[MAX_SKB_FRAGS]; #ifdef CONFIG_HAS_DMA - dma_addr_t dma_maps[MAX_SKB_FRAGS + 1]; + dma_addr_t dma_maps[MAX_SKB_FRAGS]; #endif /* Intermediate layers must ensure that destructor_arg * remains valid until skb destructor */ |