| Message ID | 20250305034550.879255-3-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | d4438ce68bf145aa1d7ed03ebf3b8ece337e3f64 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | tcp: even faster connect() under stress | expand |
From: Eric Dumazet <edumazet@google.com> Date: Wed, 5 Mar 2025 03:45:50 +0000 > 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 <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Interesting optimisation, thanks!
On Wed, Mar 5, 2025 at 11:46 AM Eric Dumazet <edumazet@google.com> wrote: > > 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 <edumazet@google.com> Thank you! Tested-by: Jason Xing <kerneljasonxing@gmail.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index f447d61d95982090aac492b31e4199534970c4fb..949641e925398f741f2d4dda5898efc683b305dc 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -527,10 +527,12 @@ static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr) 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); diff --git a/include/net/ip.h b/include/net/ip.h index ce5e59957dd553697536ddf111bb1406d9d99408..8a48ade24620b4c8e2ebb4726f27a69aac7138b0 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -357,7 +357,7 @@ static inline void inet_get_local_port_range(const struct net *net, int *low, in 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; diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 3025d2b708852acd9744709a897fca17564523d5..1e3a9573c19834cc96d0b4cbf816f86433134450 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -538,7 +538,8 @@ EXPORT_SYMBOL_GPL(__inet_lookup_established); 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); @@ -549,8 +550,6 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row, 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; @@ -1007,9 +1006,10 @@ static u32 *table_perturb; 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; @@ -1027,7 +1027,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 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; } @@ -1071,7 +1072,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 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; @@ -1090,7 +1092,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 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; } @@ -1197,11 +1200,18 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 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); diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c index 3d95f1e75a118ff8027d4ec0f33910d23b6af832..76ee521189eb77c48845eeeac9d50b3a93a250a6 100644 --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -264,7 +264,8 @@ EXPORT_SYMBOL_GPL(inet6_lookup); 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); @@ -274,8 +275,6 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row, 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; @@ -354,11 +353,19 @@ static u64 inet6_sk_port_offset(const struct sock *sk) 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);
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 <edumazet@google.com> --- include/net/inet_hashtables.h | 4 +++- include/net/ip.h | 2 +- net/ipv4/inet_hashtables.c | 26 ++++++++++++++++++-------- net/ipv6/inet6_hashtables.c | 15 +++++++++++---- 4 files changed, 33 insertions(+), 14 deletions(-)