Re: Re: An interesting performance thing ?

["Aurélien Charbon" <aurelien.charbon@ext.bull.net>]

Chuck Lever wrote:

> we might also think a little bit of the future (IPv6).
>
> IPv6 addresses are larger than IPv4 addresses, so they will need their=20
> own hash function, *or* we will have to design a reasonable hash=20
> function for variably-sized addresses now, which seems like a harder=20
> problem.

For information, in the IPv6 client support, we are currently using the=20
hash_long function by doing a xor operation between the four 32 bit=20
parts or an IPv6 address.

 static inline int ip_map_hash(struct ip_map *item)
 {
 	return hash_str(item->m_class, IP_HASHBITS) ^=20
-		hash_long((unsigned long)item->m_addr.s_addr, IP_HASHBITS);
+		hash_long((unsigned long)(item->m_addr.s6_addr32[0] ^
+			    item->m_addr.s6_addr32[1] ^
+			    item->m_addr.s6_addr32[2] ^
+			    item->m_addr.s6_addr32[3]), IP_HASHBITS);
 }

Regards,

Aur=E9lien



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