inet: call inet6_ehashfn() once from inet6_hash_connect()

inet6_ehashfn() being called from __inet6_check_established()
has a big impact on performance, as shown in the Tested section.

After prior patch, we can compute the hash for port 0
from inet6_hash_connect(), and derive each hash in
__inet_hash_connect() from this initial hash:

hash(saddr, lport, daddr, dport) == hash(saddr, 0, daddr, dport) + lport

Apply the same principle for __inet_check_established(),
although inet_ehashfn() has a smaller cost.

Tested:

Server: ulimit -n 40000; neper/tcp_crr -T 200 -F 30000 -6 --nolog
Client: ulimit -n 40000; neper/tcp_crr -T 200 -F 30000 -6 --nolog -c -H server

Before this patch:

utime_start=0.286131
utime_end=4.378886
stime_start=11.952556
stime_end=1991.655533
num_transactions=1446830
latency_min=0.001061085
latency_max=12.075275028
latency_mean=0.376375302
latency_stddev=1.361969596
num_samples=306383
throughput=151866.56

perf top:

50.01% [kernel] [k] __inet6_check_established
20.65% [kernel] [k] __inet_hash_connect
15.81% [kernel] [k] inet6_ehashfn
2.92% [kernel] [k] rcu_all_qs
2.34% [kernel] [k] __cond_resched
0.50% [kernel] [k] _raw_spin_lock
0.34% [kernel] [k] sched_balance_trigger
0.24% [kernel] [k] queued_spin_lock_slowpath

After this patch:

utime_start=0.315047
utime_end=9.257617
stime_start=7.041489
stime_end=1923.688387
num_transactions=3057968
latency_min=0.003041375
latency_max=7.056589232
latency_mean=0.141075048 # Better latency metrics
latency_stddev=0.526900516
num_samples=312996
throughput=320677.21 # 111 % increase, and 229 % for the series

perf top: inet6_ehashfn is no longer seen.

39.67% [kernel] [k] __inet_hash_connect
37.06% [kernel] [k] __inet6_check_established
4.79% [kernel] [k] rcu_all_qs
3.82% [kernel] [k] __cond_resched
1.76% [kernel] [k] sched_balance_domains
0.82% [kernel] [k] _raw_spin_lock
0.81% [kernel] [k] sched_balance_rq
0.81% [kernel] [k] sched_balance_trigger
0.76% [kernel] [k] queued_spin_lock_slowpath

Signed-off-by: Eric Dumazet <[e-mail]>
Reviewed-by: Kuniyuki Iwashima <[e-mail]>
Tested-by: Jason Xing <[e-mail]>
Reviewed-by: Jason Xing <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

include/net/inet_hashtables.h

···
 
 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 			struct sock *sk, u64 port_offset,
+			u32 hash_port0,
 			int (*check_established)(struct inet_timewait_death_row *,
 						 struct sock *, __u16,
 						 struct inet_timewait_sock **,
-						 bool rcu_lookup));
+						 bool rcu_lookup,
+						 u32 hash));
 
 int inet_hash_connect(struct inet_timewait_death_row *death_row,
 		      struct sock *sk);

include/net/ip.h

···
 bool inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high);
 
 #ifdef CONFIG_SYSCTL
-static inline bool inet_is_local_reserved_port(struct net *net, unsigned short port)
+static inline bool inet_is_local_reserved_port(const struct net *net, unsigned short port)
 {
 	if (!net->ipv4.sysctl_local_reserved_ports)
 		return false;

net/ipv4/inet_hashtables.c

···
 static int __inet_check_established(struct inet_timewait_death_row *death_row,
 				    struct sock *sk, __u16 lport,
 				    struct inet_timewait_sock **twp,
-				    bool rcu_lookup)
+				    bool rcu_lookup,
+				    u32 hash)
 {
 	struct inet_hashinfo *hinfo = death_row->hashinfo;
 	struct inet_sock *inet = inet_sk(sk);
···
 	int sdif = l3mdev_master_ifindex_by_index(net, dif);
 	INET_ADDR_COOKIE(acookie, saddr, daddr);
 	const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
-	unsigned int hash = inet_ehashfn(net, daddr, lport,
-					 saddr, inet->inet_dport);
 	struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 	struct inet_timewait_sock *tw = NULL;
 	const struct hlist_nulls_node *node;
···
 
 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 		struct sock *sk, u64 port_offset,
+		u32 hash_port0,
 		int (*check_established)(struct inet_timewait_death_row *,
 			struct sock *, __u16, struct inet_timewait_sock **,
-			bool rcu_lookup))
+			bool rcu_lookup, u32 hash))
 {
 	struct inet_hashinfo *hinfo = death_row->hashinfo;
 	struct inet_bind_hashbucket *head, *head2;
···
 
 	if (port) {
 		local_bh_disable();
-		ret = check_established(death_row, sk, port, NULL, false);
+		ret = check_established(death_row, sk, port, NULL, false,
+					hash_port0 + port);
 		local_bh_enable();
 		return ret;
 	}
···
 				rcu_read_unlock();
 				goto next_port;
 			}
-			if (!check_established(death_row, sk, port, &tw, true))
+			if (!check_established(death_row, sk, port, &tw, true,
+					       hash_port0 + port))
 				break;
 			rcu_read_unlock();
 			goto next_port;
···
 					goto next_port_unlock;
 				WARN_ON(hlist_empty(&tb->bhash2));
 				if (!check_established(death_row, sk,
-						       port, &tw, false))
+						       port, &tw, false,
+						       hash_port0 + port))
 					goto ok;
 				goto next_port_unlock;
 			}
···
 int inet_hash_connect(struct inet_timewait_death_row *death_row,
 		      struct sock *sk)
 {
+	const struct inet_sock *inet = inet_sk(sk);
+	const struct net *net = sock_net(sk);
 	u64 port_offset = 0;
+	u32 hash_port0;
 
 	if (!inet_sk(sk)->inet_num)
 		port_offset = inet_sk_port_offset(sk);
-	return __inet_hash_connect(death_row, sk, port_offset,
+
+	hash_port0 = inet_ehashfn(net, inet->inet_rcv_saddr, 0,
+				  inet->inet_daddr, inet->inet_dport);
+
+	return __inet_hash_connect(death_row, sk, port_offset, hash_port0,
 				   __inet_check_established);
 }
 EXPORT_SYMBOL_GPL(inet_hash_connect);

net/ipv6/inet6_hashtables.c

···
 static int __inet6_check_established(struct inet_timewait_death_row *death_row,
 				     struct sock *sk, const __u16 lport,
 				     struct inet_timewait_sock **twp,
-				     bool rcu_lookup)
+				     bool rcu_lookup,
+				     u32 hash)
 {
 	struct inet_hashinfo *hinfo = death_row->hashinfo;
 	struct inet_sock *inet = inet_sk(sk);
···
 	struct net *net = sock_net(sk);
 	const int sdif = l3mdev_master_ifindex_by_index(net, dif);
 	const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
-	const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
-						inet->inet_dport);
 	struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 	struct inet_timewait_sock *tw = NULL;
 	const struct hlist_nulls_node *node;
···
 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 		       struct sock *sk)
 {
+	const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
+	const struct in6_addr *saddr = &sk->sk_v6_daddr;
+	const struct inet_sock *inet = inet_sk(sk);
+	const struct net *net = sock_net(sk);
 	u64 port_offset = 0;
+	u32 hash_port0;
 
 	if (!inet_sk(sk)->inet_num)
 		port_offset = inet6_sk_port_offset(sk);
-	return __inet_hash_connect(death_row, sk, port_offset,
+
+	hash_port0 = inet6_ehashfn(net, daddr, 0, saddr, inet->inet_dport);
+
+	return __inet_hash_connect(death_row, sk, port_offset, hash_port0,
 				   __inet6_check_established);
 }
 EXPORT_SYMBOL_GPL(inet6_hash_connect);