From patchwork Tue May 11 12:04:17 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leonard Crestez X-Patchwork-Id: 434736 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C82EFC43470 for ; Tue, 11 May 2021 12:04:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99F826186A for ; Tue, 11 May 2021 12:04:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231575AbhEKMFx (ORCPT ); Tue, 11 May 2021 08:05:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44046 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231359AbhEKMFr (ORCPT ); Tue, 11 May 2021 08:05:47 -0400 Received: from mail-ed1-x52a.google.com (mail-ed1-x52a.google.com [IPv6:2a00:1450:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1CD7BC061574; Tue, 11 May 2021 05:04:40 -0700 (PDT) Received: by mail-ed1-x52a.google.com with SMTP id s6so22514200edu.10; Tue, 11 May 2021 05:04:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=hJsw+lxKd2cb0b24j+83WH1uLaEto1TRoqJQ5s2GyQw=; b=pFbmxPia6cPDL8Awb5a8lY1GeCvq/Eu7I5OzOoAHLtTDi8T1o+s1QGH+lj1+2gNyyG 5DlTjRd7pV8so+YSUx3Vy8B+WAP+CpMbHowMpq9jmXE7qkd7uLOVPlcyuwVgpyknjBMY pv50pn21wdpei/HpSx4eRW4mJyy59+6dLfeBZhCOlO9gbc45Us2ixzhQgmHlkgb97JZ1 tSN+ivUdegqNdUja2P6DMPXy0nE8QS58zHY2nE7pnYTIiH0vS4CeI/A0YyAgiBtB4K7E j6VgQY5LzhY1OWTyBqUMbrlpwR/AGrkYY1VePyKvl05dl2vMkEYkcX8Aa84/iThfqVVk zJ4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=hJsw+lxKd2cb0b24j+83WH1uLaEto1TRoqJQ5s2GyQw=; b=uK6KdCTK7cO4PLs2n4Bb+KrZSaVyrKTIa0MkuXBWjZRShzfZjL/tSs7mWsvJjbRkuH 02NTdgI2+Yuww9xeSj5OrwvMsyMqE2gHOyrGcdUhjZ4JTg+lIjDbBE/Kk4gF901ar2h6 rJIWtMiJBWVeIN6mkTVxA3b4xxOpsfzBw7H0TqAgAod9fA/JdlvLhNk9iUR+Ve98fT8O qoC8F8fZiwrnL+BALK/VLVDYPVcmjj4VNNCkFKU+Yz0ZY9nqF4DLgSXVEKCGdX8n3IaG Fdf6FA+SczgGyrN7iKpB7VYQPRBZTq1K5xsiUeMFuK5DPOrz2ljMwEr5sBQtKyIh2LP1 OGiA== X-Gm-Message-State: AOAM5324bboxIMwmX1Hl05PIvQVlqpYAFzXVf9Z9kylewcbH1q1dv2aR fP4wnq7L4gcjGafXg/iPBv4= X-Google-Smtp-Source: ABdhPJwUDjbq3fzDucfBHjhDPlfU72GnCoS3a0ZLgfCQOJOaj91kTubBkerTs7LeckDpkSm+b6iSJg== X-Received: by 2002:a05:6402:1115:: with SMTP id u21mr35586687edv.383.1620734678860; Tue, 11 May 2021 05:04:38 -0700 (PDT) Received: from localhost.localdomain ([2a04:241e:502:1d80:58c4:451b:d037:737c]) by smtp.gmail.com with ESMTPSA id o20sm8212615eds.20.2021.05.11.05.04.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 May 2021 05:04:38 -0700 (PDT) From: Leonard Crestez To: Neal Cardwell , Matt Mathis Cc: "David S. Miller" , Eric Dumazet , Willem de Bruijn , Jakub Kicinski , Hideaki YOSHIFUJI , David Ahern , John Heffner , Leonard Crestez , Soheil Hassas Yeganeh , Roopa Prabhu , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC 2/3] tcp: Use mtu probes if RACK is enabled Date: Tue, 11 May 2021 15:04:17 +0300 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org RACK allows detecting a loss in min_rtt / 4 based on just one extra packet. If enabled use this instead of relying of fast retransmit. Suggested-by: Neal Cardwell Signed-off-by: Leonard Crestez --- Documentation/networking/ip-sysctl.rst | 5 +++++ include/net/netns/ipv4.h | 1 + net/ipv4/sysctl_net_ipv4.c | 7 +++++++ net/ipv4/tcp_ipv4.c | 1 + net/ipv4/tcp_output.c | 22 +++++++++++++++++++++- 5 files changed, 35 insertions(+), 1 deletion(-) diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 108a5ee227d3..4f6ac69f61e7 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -325,10 +325,15 @@ tcp_mtu_probe_floor - INTEGER tcp_mtu_probe_autocork - BOOLEAN Take into account mtu probe size when accumulating data via autocorking. Default: 1 +tcp_mtu_probe_rack - BOOLEAN + Try to use shorter probes if RACK is also enabled + + Default: 1 + tcp_min_snd_mss - INTEGER TCP SYN and SYNACK messages usually advertise an ADVMSS option, as described in RFC 1122 and RFC 6691. If this ADVMSS option is smaller than tcp_min_snd_mss, diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index 3a2d8bf2b20a..298e65d8605c 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -113,10 +113,11 @@ struct netns_ipv4 { u8 sysctl_tcp_l3mdev_accept; #endif u8 sysctl_tcp_mtu_probing; int sysctl_tcp_mtu_probe_floor; int sysctl_tcp_mtu_probe_autocork; + int sysctl_tcp_mtu_probe_rack; int sysctl_tcp_base_mss; int sysctl_tcp_min_snd_mss; int sysctl_tcp_probe_threshold; u32 sysctl_tcp_probe_interval; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index e19176c17973..f9366f35ff9c 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -834,10 +834,17 @@ static struct ctl_table ipv4_net_table[] = { .data = &init_net.ipv4.sysctl_tcp_mtu_probe_autocork, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "tcp_mtu_probe_rack", + .data = &init_net.ipv4.sysctl_tcp_mtu_probe_rack, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, { .procname = "tcp_probe_threshold", .data = &init_net.ipv4.sysctl_tcp_probe_threshold, .maxlen = sizeof(int), .mode = 0644, diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 7e75423c08c9..4928fcd6e233 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2890,10 +2890,11 @@ static int __net_init tcp_sk_init(struct net *net) net->ipv4.sysctl_tcp_min_snd_mss = TCP_MIN_SND_MSS; net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD; net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL; net->ipv4.sysctl_tcp_mtu_probe_floor = TCP_MIN_SND_MSS; net->ipv4.sysctl_tcp_mtu_probe_autocork = 1; + net->ipv4.sysctl_tcp_mtu_probe_rack = 1; net->ipv4.sysctl_tcp_keepalive_time = TCP_KEEPALIVE_TIME; net->ipv4.sysctl_tcp_keepalive_probes = TCP_KEEPALIVE_PROBES; net->ipv4.sysctl_tcp_keepalive_intvl = TCP_KEEPALIVE_INTVL; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 5a320d792ec4..7cd1e8fd9749 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2311,27 +2311,47 @@ static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) } return true; } +static int tcp_mtu_probe_is_rack(const struct sock *sk) +{ + struct net *net = sock_net(sk); + + return (net->ipv4.sysctl_tcp_recovery & TCP_RACK_LOSS_DETECTION && + net->ipv4.sysctl_tcp_mtu_probe_rack); +} + /* Calculate the size of an MTU probe * Probing the MTU requires one packets which is larger that current MSS as well * as enough following mtu-sized packets to ensure that a probe loss can be * detected without a full Retransmit Time out. */ int tcp_mtu_probe_size_needed(struct sock *sk, int *probe_size) { struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); + struct net *net = sock_net(sk); int probe_size_val; int size_needed; /* This might be a little slow: */ probe_size_val = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + icsk->icsk_mtup.search_low) >> 1); if (probe_size) *probe_size = probe_size_val; - size_needed = probe_size_val + (tp->reordering + 1) * tp->mss_cache; + + if (tcp_mtu_probe_is_rack(sk)) { + /* RACK allows recovering in min_rtt / 4 based on just one extra packet + * Use two to account for unrelated losses + */ + size_needed = probe_size_val + 2 * tp->mss_cache; + } else { + /* Without RACK send enough extra packets to trigger fast retransmit + * This is dynamic DupThresh + 1 + */ + size_needed = probe_size_val + (tp->reordering + 1) * tp->mss_cache; + } return size_needed; } /* Create a new MTU probe if we are ready.