diff options
| author | Patrick McHardy <kaber@trash.net> | 2007-12-17 22:45:52 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-01-28 14:59:11 -0800 |
| commit | 34498825cb9062192b77fa02dae672a4fe6eec70 (patch) | |
| tree | 7f856aff21ae3ab1328ab9bcf3549bca8e13df35 /net/ipv4/netfilter/ipt_CLUSTERIP.c | |
| parent | 7b21e09d1c17ef0296ec5a6df231a6c5c87b2fd7 (diff) | |
[NETFILTER]: non-power-of-two jhash optimizations
Apply Eric Dumazet's jhash optimizations where applicable. Quoting Eric:
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: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/netfilter/ipt_CLUSTERIP.c')
| -rw-r--r-- | net/ipv4/netfilter/ipt_CLUSTERIP.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c index a48e26449fd..df39ca07fb1 100644 --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -273,7 +273,7 @@ clusterip_hashfn(const struct sk_buff *skb, } /* node numbers are 1..n, not 0..n */ - return (hashval % config->num_total_nodes) + 1; + return (((u64)hashval * config->num_total_nodes) >> 32) + 1; } static inline int |