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gro: Optimise Ethernet header comparison

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This patch optimises the Ethernet header comparison to use 2-byte
and 4-byte xors instead of memcmp.  In order to facilitate this,
the actual comparison is now carried out by the callers of the
shared dev_gro_receive function.

This has a significant impact when receiving 1500B packets through
10GbE.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2009-02-08 18:00:37 +00:00 • committed by David S. Miller
parent 4ae5544f9a
commit aa4b9f533e
4 changed files with 33 additions and 22 deletions
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21
include/linux/etherdevice.h
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@ -184,4 +184,25 @@ static inline unsigned compare_ether_addr_64bits(const u8 addr1[6+2],
}
#endif /* __KERNEL__ */
/**
* compare_ether_header - Compare two Ethernet headers
* @a: Pointer to Ethernet header
* @b: Pointer to Ethernet header
*
* Compare two ethernet headers, returns 0 if equal.
* This assumes that the network header (i.e., IP header) is 4-byte
* aligned OR the platform can handle unaligned access. This is the
* case for all packets coming into netif_receive_skb or similar
* entry points.
*/
static inline int compare_ether_header(const void *a, const void *b)
{
u32 *a32 = (u32 *)((u8 *)a + 2);
u32 *b32 = (u32 *)((u8 *)b + 2);
return (*(u16 *)a ^ *(u16 *)b) | (a32[0] ^ b32[0]) |
(a32[1] ^ b32[1]) | (a32[2] ^ b32[2]);
}
#endif /* _LINUX_ETHERDEVICE_H */