From patchwork Sun Mar 2 12:42:37 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 13997802 X-Patchwork-Delegate: kuba@kernel.org Received: from mail-qt1-f202.google.com (mail-qt1-f202.google.com [209.85.160.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 268BB1E3DE5 for ; Sun, 2 Mar 2025 12:42:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740919366; cv=none; b=DHcQdVB70reWyM8SFOxKcbG/Wk+/7ezcQ+YTFOQHXB+1CDRtKW92ejU3vyd+vVsR1uXHuadKWPTPqbm4eDNk5irF1A8fCvuj49nK1jkuGaFu51pPvR3Eo3l4Whf9uFVDpEbmKuSpUHgQAYe/XPjk6Ctg6+97W7wWhVZoZIjc83E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740919366; c=relaxed/simple; bh=ItXP/zyRAh+/67PmK7Z+y9460lXos/4E+fsmUnOBZBA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=q+muPrvc5msZpCwt00rQ1cSNCBEwyNlD1aLQPz9qe+7y/dr7MbAfCP54ci4UgWepibJ7GFcPMG5vqFaYqy4kp2wkUbwbRumxrmzr7JR2jQK+Ofv6TWvVo0qiyQMWTv07UL3EGE6NHHKLn6CZl2UV0f3+hDUPHOq7xzMWzPe3tBI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=heFFxyzk; arc=none smtp.client-ip=209.85.160.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="heFFxyzk" Received: by mail-qt1-f202.google.com with SMTP id d75a77b69052e-471ec7f1969so92485911cf.1 for ; Sun, 02 Mar 2025 04:42:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1740919364; x=1741524164; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=bIbXbn1qyNwXG/XGNxdRDEuAyo93hNv8FKSURSQEbM4=; b=heFFxyzkco9dM3swFNshNCfwIIGaQfk/VQihNIyjTgRgFJIqbCRrDDDscndB8BOudQ 7fA2ywGdrx2vAsdkl84LW4Jd06huEFaZ0cbqZvSQG8Dt/WSpuGQlEzQ2qZgkJyoJoKGV 8Pf3EiQ/W0uUITZtUhOAr1YdmBpNoN+1erDcRws/bpbgIEgkv+oVyb+KFfW1XbjuY6zA 4S5rT9cxTGDkzR45o42/fVCE9IlpXYjU+Rqa7MFJLBMi92l0zGcJFlNnj8X4jT/hGUK6 RG970mrjxXCK7xLDjVGA+ayssHAMDiiC9XJ62Hse8uBKvP+Nf9Oyf3pMEi42I2ZW48Hm GHEw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740919364; x=1741524164; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=bIbXbn1qyNwXG/XGNxdRDEuAyo93hNv8FKSURSQEbM4=; b=S9fuVkKZAwcpCuf3EB00pfkq3+Ng+Jp7PTKtU6EeGEYKmasR4rOuxq4Glf53bE9xn+ uQ52TPnvbuqQnsYwc2mUOYbQczGF8xrAzspC4YqInxYAX16RYMedgtAKFpOXraeyaJIp p1NZdK6ZMq0fgPUbylNztAWOYfRQIKj9DW+7R2bQjFrk/0dJvDqS50OtRZq1y3Vvh//S G3vaqyNvlDub8+UkaGuTkqrgU1yY1BL1oxfseRWsiSncam7O7IotpHKmYA0Vcs9Jdz3C DOQQO5Ll5pACSlOrG3/yw0HLASuDdwSdVPatSss3q09M0UAT64rY+LMWcg07qejzbpuV zKNw== X-Forwarded-Encrypted: i=1; AJvYcCVxP2C6KPYnM66UGsAvkGvd5HWJ7PIP8N3+ttQqq/XxKXJypXRsCvIsVgVXUI273gPnXWAESn4=@vger.kernel.org X-Gm-Message-State: AOJu0YwOUmAPM9gl51Tq5UK2QBnA2piX2lFvDUGFhKesnwjjF7mYG5xu TEQpvZUUXbbp4VYlYwom+U2O6i4YGj5HdSRUUExuFb9BuV1rrJcnA9z2BmD7O0RTvw6cl9NGJwg HUU1fPJS/JQ== X-Google-Smtp-Source: AGHT+IHof4z7aGHpuS92kAvQXiZc6abSJZ/Z16oiPqjR33sve5qy+MbHUoXtRbDD/TQ8hkxyarz6mnFTA2T4ng== X-Received: from qtbfi5.prod.google.com ([2002:a05:622a:58c5:b0:472:3db:8d3c]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:ac8:5f07:0:b0:471:fa00:fb9b with SMTP id d75a77b69052e-473d8f99c26mr199701181cf.7.1740919364071; Sun, 02 Mar 2025 04:42:44 -0800 (PST) Date: Sun, 2 Mar 2025 12:42:37 +0000 In-Reply-To: <20250302124237.3913746-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250302124237.3913746-1-edumazet@google.com> X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250302124237.3913746-5-edumazet@google.com> Subject: [PATCH net-next 4/4] tcp: use RCU lookup in __inet_hash_connect() From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni , Neal Cardwell Cc: Kuniyuki Iwashima , Jason Xing , Simon Horman , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet X-Patchwork-Delegate: kuba@kernel.org When __inet_hash_connect() has to try many 4-tuples before finding an available one, we see a high spinlock cost from the many spin_lock_bh(&head->lock) performed in its loop. This patch adds an RCU lookup to avoid the spinlock cost. check_established() gets a new @rcu_lookup argument. First reason is to not make any changes while head->lock is not held. Second reason is to not make this RCU lookup a second time after the spinlock has been acquired. 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 series: utime_start=0.288582 utime_end=1.548707 stime_start=20.637138 stime_end=2002.489845 num_transactions=484453 latency_min=0.156279245 latency_max=20.922042756 latency_mean=1.546521274 latency_stddev=3.936005194 num_samples=312537 throughput=47426.00 perf top on the client: 49.54% [kernel] [k] _raw_spin_lock 25.87% [kernel] [k] _raw_spin_lock_bh 5.97% [kernel] [k] queued_spin_lock_slowpath 5.67% [kernel] [k] __inet_hash_connect 3.53% [kernel] [k] __inet6_check_established 3.48% [kernel] [k] inet6_ehashfn 0.64% [kernel] [k] rcu_all_qs After this series: utime_start=0.271607 utime_end=3.847111 stime_start=18.407684 stime_end=1997.485557 num_transactions=1350742 latency_min=0.014131929 latency_max=17.895073144 latency_mean=0.505675853 # Nice reduction of latency metrics latency_stddev=2.125164772 num_samples=307884 throughput=139866.80 # 190 % increase perf top on client: 56.86% [kernel] [k] __inet6_check_established 17.96% [kernel] [k] __inet_hash_connect 13.88% [kernel] [k] inet6_ehashfn 2.52% [kernel] [k] rcu_all_qs 2.01% [kernel] [k] __cond_resched 0.41% [kernel] [k] _raw_spin_lock Signed-off-by: Eric Dumazet Reviewed-by: Jason Xing Tested-by: Jason Xing --- include/net/inet_hashtables.h | 3 +- net/ipv4/inet_hashtables.c | 52 +++++++++++++++++++++++------------ net/ipv6/inet6_hashtables.c | 24 ++++++++-------- 3 files changed, 50 insertions(+), 29 deletions(-) diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 73c0e4087fd1a6d0d2a40ab0394165e07b08ed6d..b12797f13c9a3d66fab99c877d059f9c29c30d11 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -529,7 +529,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, struct sock *sk, u64 port_offset, int (*check_established)(struct inet_timewait_death_row *, struct sock *, __u16, - struct inet_timewait_sock **)); + struct inet_timewait_sock **, + bool rcu_lookup)); int inet_hash_connect(struct inet_timewait_death_row *death_row, struct sock *sk); diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index b737e13f8459c53428980221355344327c4bc8dd..d1b5f45ee718410fdf3e78c113c7ebd4a1ddba40 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -537,7 +537,8 @@ EXPORT_SYMBOL_GPL(__inet_lookup_established); /* called with local bh disabled */ static int __inet_check_established(struct inet_timewait_death_row *death_row, struct sock *sk, __u16 lport, - struct inet_timewait_sock **twp) + struct inet_timewait_sock **twp, + bool rcu_lookup) { struct inet_hashinfo *hinfo = death_row->hashinfo; struct inet_sock *inet = inet_sk(sk); @@ -556,17 +557,17 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row, struct sock *sk2; spinlock_t *lock; - rcu_read_lock(); - sk_nulls_for_each(sk2, node, &head->chain) { - if (sk2->sk_hash != hash || - !inet_match(net, sk2, acookie, ports, dif, sdif)) - continue; - if (sk2->sk_state == TCP_TIME_WAIT) - break; - rcu_read_unlock(); - return -EADDRNOTAVAIL; + if (rcu_lookup) { + sk_nulls_for_each(sk2, node, &head->chain) { + if (sk2->sk_hash != hash || + !inet_match(net, sk2, acookie, ports, dif, sdif)) + continue; + if (sk2->sk_state == TCP_TIME_WAIT) + break; + return -EADDRNOTAVAIL; + } + return 0; } - rcu_read_unlock(); lock = inet_ehash_lockp(hinfo, hash); spin_lock(lock); @@ -1007,7 +1008,8 @@ static u32 *table_perturb; int __inet_hash_connect(struct inet_timewait_death_row *death_row, struct sock *sk, u64 port_offset, int (*check_established)(struct inet_timewait_death_row *, - struct sock *, __u16, struct inet_timewait_sock **)) + struct sock *, __u16, struct inet_timewait_sock **, + bool rcu_lookup)) { struct inet_hashinfo *hinfo = death_row->hashinfo; struct inet_bind_hashbucket *head, *head2; @@ -1025,7 +1027,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, if (port) { local_bh_disable(); - ret = check_established(death_row, sk, port, NULL); + ret = check_established(death_row, sk, port, NULL, false); local_bh_enable(); return ret; } @@ -1061,6 +1063,21 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, continue; head = &hinfo->bhash[inet_bhashfn(net, port, hinfo->bhash_size)]; + rcu_read_lock(); + hlist_for_each_entry_rcu(tb, &head->chain, node) { + if (!inet_bind_bucket_match(tb, net, port, l3mdev)) + continue; + if (tb->fastreuse >= 0 || tb->fastreuseport >= 0) { + rcu_read_unlock(); + goto next_port; + } + if (!check_established(death_row, sk, port, &tw, true)) + break; + rcu_read_unlock(); + goto next_port; + } + rcu_read_unlock(); + spin_lock_bh(&head->lock); /* Does not bother with rcv_saddr checks, because @@ -1070,12 +1087,12 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, if (inet_bind_bucket_match(tb, net, port, l3mdev)) { if (tb->fastreuse >= 0 || tb->fastreuseport >= 0) - goto next_port; + goto next_port_unlock; WARN_ON(hlist_empty(&tb->bhash2)); if (!check_established(death_row, sk, - port, &tw)) + port, &tw, false)) goto ok; - goto next_port; + goto next_port_unlock; } } @@ -1089,8 +1106,9 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, tb->fastreuse = -1; tb->fastreuseport = -1; goto ok; -next_port: +next_port_unlock: spin_unlock_bh(&head->lock); +next_port: cond_resched(); } diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c index 3604a5cae5d29a25d24f9513308334ff8e64b083..9be315496459fcb391123a07ac887e2f59d27360 100644 --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -263,7 +263,8 @@ 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) + struct inet_timewait_sock **twp, + bool rcu_lookup) { struct inet_hashinfo *hinfo = death_row->hashinfo; struct inet_sock *inet = inet_sk(sk); @@ -281,17 +282,18 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row, struct sock *sk2; spinlock_t *lock; - rcu_read_lock(); - sk_nulls_for_each(sk2, node, &head->chain) { - if (sk2->sk_hash != hash || - !inet6_match(net, sk2, saddr, daddr, ports, dif, sdif)) - continue; - if (sk2->sk_state == TCP_TIME_WAIT) - break; - rcu_read_unlock(); - return -EADDRNOTAVAIL; + if (rcu_lookup) { + sk_nulls_for_each(sk2, node, &head->chain) { + if (sk2->sk_hash != hash || + !inet6_match(net, sk2, saddr, daddr, + ports, dif, sdif)) + continue; + if (sk2->sk_state == TCP_TIME_WAIT) + break; + return -EADDRNOTAVAIL; + } + return 0; } - rcu_read_unlock(); lock = inet_ehash_lockp(hinfo, hash); spin_lock(lock);