Commit d2c806ab authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: conntrack: use siphash_4u64 



This function is used for every packet, siphash_4u64 is noticeably faster
than using local buffer + siphash:

Before:
  1.23%  kpktgend_0       [kernel.vmlinux]     [k] __siphash_unaligned
  0.14%  kpktgend_0       [nf_conntrack]       [k] hash_conntrack_raw
After:
  0.79%  kpktgend_0       [kernel.vmlinux]     [k] siphash_4u64
  0.15%  kpktgend_0       [nf_conntrack]       [k] hash_conntrack_raw

In the pktgen test this gives about ~2.4% performance improvement.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 971095c6

net/netfilter/nf_conntrack_core.c

+13 −17
Original line number Diff line number Diff line
@@ -211,28 +211,24 @@ static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple, 
			      unsigned int zoneid,

			      const struct net *net)

{

	struct {

		struct nf_conntrack_man src;

		union nf_inet_addr dst_addr;

		unsigned int zone;

		u32 net_mix;

		u16 dport;

		u16 proto;

	} __aligned(SIPHASH_ALIGNMENT) combined;

	u64 a, b, c, d;



	get_random_once(&nf_conntrack_hash_rnd, sizeof(nf_conntrack_hash_rnd));



	memset(&combined, 0, sizeof(combined));

	/* The direction must be ignored, handle usable tuplehash members manually */

	a = (u64)tuple->src.u3.all[0] << 32 | tuple->src.u3.all[3];

	b = (u64)tuple->dst.u3.all[0] << 32 | tuple->dst.u3.all[3];



	/* The direction must be ignored, so handle usable members manually. */

	combined.src = tuple->src;

	combined.dst_addr = tuple->dst.u3;

	combined.zone = zoneid;

	combined.net_mix = net_hash_mix(net);

	combined.dport = (__force __u16)tuple->dst.u.all;

	combined.proto = tuple->dst.protonum;

	c = (__force u64)tuple->src.u.all << 32 | (__force u64)tuple->dst.u.all << 16;

	c |= tuple->dst.protonum;



	return (u32)siphash(&combined, sizeof(combined), &nf_conntrack_hash_rnd);

	d = (u64)zoneid << 32 | net_hash_mix(net);



	/* IPv4: u3.all[1,2,3] == 0 */

	c ^= (u64)tuple->src.u3.all[1] << 32 | tuple->src.u3.all[2];

	d += (u64)tuple->dst.u3.all[1] << 32 | tuple->dst.u3.all[2];



	return (u32)siphash_4u64(a, b, c, d, &nf_conntrack_hash_rnd);

}



static u32 scale_hash(u32 hash)