linux/include/net/inet6_hashtables.h
Tom Herbert 5ba24953e9 soreuseport: TCP/IPv6 implementation
Motivation for soreuseport would be something like a web server
binding to port 80 running with multiple threads, where each thread
might have it's own listener socket.  This could be done as an
alternative to other models: 1) have one listener thread which
dispatches completed connections to workers. 2) accept on a single
listener socket from multiple threads.  In case #1 the listener thread
can easily become the bottleneck with high connection turn-over rate.
In case #2, the proportion of connections accepted per thread tends
to be uneven under high connection load (assuming simple event loop:
while (1) { accept(); process() }, wakeup does not promote fairness
among the sockets.  We have seen the  disproportion to be as high
as 3:1 ratio between thread accepting most connections and the one
accepting the fewest.  With so_reusport the distribution is
uniform.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-01-23 13:44:01 -05:00

119 lines
3.5 KiB
C

/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Authors: Lotsa people, from code originally in tcp
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _INET6_HASHTABLES_H
#define _INET6_HASHTABLES_H
#if IS_ENABLED(CONFIG_IPV6)
#include <linux/in6.h>
#include <linux/ipv6.h>
#include <linux/types.h>
#include <linux/jhash.h>
#include <net/inet_sock.h>
#include <net/ipv6.h>
#include <net/netns/hash.h>
struct inet_hashinfo;
/* I have no idea if this is a good hash for v6 or not. -DaveM */
static inline unsigned int inet6_ehashfn(struct net *net,
const struct in6_addr *laddr, const u16 lport,
const struct in6_addr *faddr, const __be16 fport)
{
u32 ports = (lport ^ (__force u16)fport);
return jhash_3words((__force u32)laddr->s6_addr32[3],
(__force u32)faddr->s6_addr32[3],
ports, inet_ehash_secret + net_hash_mix(net));
}
static inline int inet6_sk_ehashfn(const struct sock *sk)
{
const struct inet_sock *inet = inet_sk(sk);
const struct ipv6_pinfo *np = inet6_sk(sk);
const struct in6_addr *laddr = &np->rcv_saddr;
const struct in6_addr *faddr = &np->daddr;
const __u16 lport = inet->inet_num;
const __be16 fport = inet->inet_dport;
struct net *net = sock_net(sk);
return inet6_ehashfn(net, laddr, lport, faddr, fport);
}
extern int __inet6_hash(struct sock *sk, struct inet_timewait_sock *twp);
/*
* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
* we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
*
* The sockhash lock must be held as a reader here.
*/
extern struct sock *__inet6_lookup_established(struct net *net,
struct inet_hashinfo *hashinfo,
const struct in6_addr *saddr,
const __be16 sport,
const struct in6_addr *daddr,
const u16 hnum,
const int dif);
extern struct sock *inet6_lookup_listener(struct net *net,
struct inet_hashinfo *hashinfo,
const struct in6_addr *saddr,
const __be16 sport,
const struct in6_addr *daddr,
const unsigned short hnum,
const int dif);
static inline struct sock *__inet6_lookup(struct net *net,
struct inet_hashinfo *hashinfo,
const struct in6_addr *saddr,
const __be16 sport,
const struct in6_addr *daddr,
const u16 hnum,
const int dif)
{
struct sock *sk = __inet6_lookup_established(net, hashinfo, saddr,
sport, daddr, hnum, dif);
if (sk)
return sk;
return inet6_lookup_listener(net, hashinfo, saddr, sport,
daddr, hnum, dif);
}
static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo,
struct sk_buff *skb,
const __be16 sport,
const __be16 dport)
{
struct sock *sk = skb_steal_sock(skb);
if (sk)
return sk;
return __inet6_lookup(dev_net(skb_dst(skb)->dev), hashinfo,
&ipv6_hdr(skb)->saddr, sport,
&ipv6_hdr(skb)->daddr, ntohs(dport),
inet6_iif(skb));
}
extern struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
const struct in6_addr *saddr, const __be16 sport,
const struct in6_addr *daddr, const __be16 dport,
const int dif);
#endif /* IS_ENABLED(CONFIG_IPV6) */
#endif /* _INET6_HASHTABLES_H */