[NETFILTER]: xt_hashlimit: speedup hash_dst()

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1) Using jhash2() instead of jhash() is a litle bit faster if applicable.

2) Thanks to jhash, hash value uses full 32 bits.
   Instead of returning hash % size (implying a divide)
   we return the high 32 bits of the (hash * size) that will
   give results between [0 and size-1] and same hash distribution.

  On most cpus, a multiply is less expensive than a divide, by an order
  of magnitude.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

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Eric Dumazet 2007-12-17 22:45:13 -08:00 • committed by David S. Miller

parent 22c2d8bca2

commit e2f82ac3fc

1 changed files with 10 additions and 1 deletions

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net/netfilter/xt_hashlimit.c

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