From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3630ECAAD8 for ; Tue, 30 Aug 2022 19:17:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230098AbiH3TRB (ORCPT ); Tue, 30 Aug 2022 15:17:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49984 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229781AbiH3TQw (ORCPT ); Tue, 30 Aug 2022 15:16:52 -0400 Received: from smtp-fw-2101.amazon.com (smtp-fw-2101.amazon.com [72.21.196.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D22866A499 for ; Tue, 30 Aug 2022 12:16:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1661887011; x=1693423011; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=b3Byx9LpyVVRCD6Cc9T3C09NLY+EG542BJqLca9XEwQ=; b=j7VwsIUQN9lHf1MnSXHxb73PBav1mNogncJnmHGXKM3B4+AKXWYeRSeA +FB9yCgiexDbhp4UjsBLYqJ9rMdtxed5C/lTVTMCaJoaJBGCV9MWGodHS oWAmolb5M/ygApHguBNvEORyAgZkZMYrot3XKTlucRgfzRt/ZvFFZh9rf A=; X-IronPort-AV: E=Sophos;i="5.93,275,1654560000"; d="scan'208";a="235790184" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-pdx-2b-1f9d5b26.us-west-2.amazon.com) ([10.43.8.6]) by smtp-border-fw-2101.iad2.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Aug 2022 19:16:50 +0000 Received: from EX13MTAUWB001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan3.pdx.amazon.com [10.236.137.198]) by email-inbound-relay-pdx-2b-1f9d5b26.us-west-2.amazon.com (Postfix) with ESMTPS id 061BE44DD0; Tue, 30 Aug 2022 19:16:49 +0000 (UTC) Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX13MTAUWB001.ant.amazon.com (10.43.161.207) with Microsoft SMTP Server (TLS) id 15.0.1497.38; Tue, 30 Aug 2022 19:16:46 +0000 Received: from 88665a182662.ant.amazon.com.com (10.43.161.172) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1118.12; Tue, 30 Aug 2022 19:16:43 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni CC: Kuniyuki Iwashima , Kuniyuki Iwashima , Subject: [PATCH v3 net-next 4/5] tcp: Save unnecessary inet_twsk_purge() calls. Date: Tue, 30 Aug 2022 12:15:17 -0700 Message-ID: <20220830191518.77083-5-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220830191518.77083-1-kuniyu@amazon.com> References: <20220830191518.77083-1-kuniyu@amazon.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.43.161.172] X-ClientProxiedBy: EX13D18UWA001.ant.amazon.com (10.43.160.11) To EX19D004ANA001.ant.amazon.com (10.37.240.138) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org While destroying netns, we call inet_twsk_purge() in tcp_sk_exit_batch() and tcpv6_net_exit_batch() for AF_INET and AF_INET6. These commands trigger the kernel to walk through the potentially big ehash twice even though the netns has no TIME_WAIT sockets. # ip netns add test # ip netns del test or # unshare -n /bin/true >/dev/null AF_INET6 uses module_init() to be loaded after AF_INET which uses fs_initcall(), so tcpv6_net_ops is always registered after tcp_sk_ops. Also, we clean up netns in the reverse order, so tcpv6_net_exit_batch() is always called before tcp_sk_exit_batch(). The characteristic enables us to save such unneeded iterations when all netns in net_exit_list have no tw sockets. This change eliminates the tax by the additional unshare() described in the next patch to guarantee the per-netns ehash size. Tested: # echo cleanup_net > /sys/kernel/debug/tracing/set_ftrace_filter # echo inet_twsk_purge >> /sys/kernel/debug/tracing/set_ftrace_filter # echo function > /sys/kernel/debug/tracing/current_tracer # cat ./add_del_unshare.sh for i in `seq 1 40` do (for j in `seq 1 100` ; do unshare -n /bin/true >/dev/null ; done) & done wait; # ./add_del_unshare.sh Before the patch: # cat /sys/kernel/debug/tracing/trace_pipe kworker/u128:0-8 [031] ...1. 174.162765: cleanup_net <-process_one_work kworker/u128:0-8 [031] ...1. 174.240796: inet_twsk_purge <-cleanup_net kworker/u128:0-8 [032] ...1. 174.244759: inet_twsk_purge <-tcp_sk_exit_batch kworker/u128:0-8 [034] ...1. 174.290861: cleanup_net <-process_one_work kworker/u128:0-8 [039] ...1. 175.245027: inet_twsk_purge <-cleanup_net kworker/u128:0-8 [046] ...1. 175.290541: inet_twsk_purge <-tcp_sk_exit_batch kworker/u128:0-8 [037] ...1. 175.321046: cleanup_net <-process_one_work kworker/u128:0-8 [024] ...1. 175.941633: inet_twsk_purge <-cleanup_net kworker/u128:0-8 [025] ...1. 176.242539: inet_twsk_purge <-tcp_sk_exit_batch After: # cat /sys/kernel/debug/tracing/trace_pipe kworker/u128:0-8 [038] ...1. 428.116174: cleanup_net <-process_one_work kworker/u128:0-8 [038] ...1. 428.262532: cleanup_net <-process_one_work kworker/u128:0-8 [030] ...1. 429.292645: cleanup_net <-process_one_work Signed-off-by: Kuniyuki Iwashima --- include/net/tcp.h | 1 + net/ipv4/tcp_ipv4.c | 6 ++++-- net/ipv4/tcp_minisocks.c | 24 ++++++++++++++++++++++++ net/ipv6/tcp_ipv6.c | 2 +- 4 files changed, 30 insertions(+), 3 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index d10962b9f0d0..f60996c1d7b3 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -346,6 +346,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb); void tcp_rcv_space_adjust(struct sock *sk); int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); void tcp_twsk_destructor(struct sock *sk); +void tcp_twsk_purge(struct list_head *net_exit_list, int family); ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags); diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index b07930643b11..f4a502d57d45 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -3109,8 +3109,10 @@ static void __net_exit tcp_sk_exit(struct net *net) if (net->ipv4.tcp_congestion_control) bpf_module_put(net->ipv4.tcp_congestion_control, net->ipv4.tcp_congestion_control->owner); - if (refcount_dec_and_test(&tcp_death_row->tw_refcount)) + if (refcount_dec_and_test(&tcp_death_row->tw_refcount)) { kfree(tcp_death_row); + net->ipv4.tcp_death_row = NULL; + } } static int __net_init tcp_sk_init(struct net *net) @@ -3210,7 +3212,7 @@ static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list) { struct net *net; - inet_twsk_purge(&tcp_hashinfo, AF_INET); + tcp_twsk_purge(net_exit_list, AF_INET); list_for_each_entry(net, net_exit_list, exit_list) tcp_fastopen_ctx_destroy(net); diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 361aad67c6d6..9168c5a33344 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -347,6 +347,30 @@ void tcp_twsk_destructor(struct sock *sk) } EXPORT_SYMBOL_GPL(tcp_twsk_destructor); +void tcp_twsk_purge(struct list_head *net_exit_list, int family) +{ + struct net *net; + + list_for_each_entry(net, net_exit_list, exit_list) { + if (!net->ipv4.tcp_death_row) + continue; + + /* AF_INET6 using module_init() is always registered after + * AF_INET using fs_initcall() and cleaned up in the reverse + * order. + * + * The last refcount is decremented later in tcp_sk_exit(). + */ + if (IS_ENABLED(CONFIG_IPV6) && family == AF_INET6 && + refcount_read(&net->ipv4.tcp_death_row->tw_refcount) == 1) + continue; + + inet_twsk_purge(&tcp_hashinfo, family); + break; + } +} +EXPORT_SYMBOL_GPL(tcp_twsk_purge); + /* Warning : This function is called without sk_listener being locked. * Be sure to read socket fields once, as their value could change under us. */ diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 27b2fd98a2c4..9cbc7f0d7149 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -2229,7 +2229,7 @@ static void __net_exit tcpv6_net_exit(struct net *net) static void __net_exit tcpv6_net_exit_batch(struct list_head *net_exit_list) { - inet_twsk_purge(&tcp_hashinfo, AF_INET6); + tcp_twsk_purge(net_exit_list, AF_INET6); } static struct pernet_operations tcpv6_net_ops = { -- 2.30.2