From owner-svn-src-head@freebsd.org Thu Sep 24 19:35:35 2020 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 8104D426099; Thu, 24 Sep 2020 19:35:35 +0000 (UTC) (envelope-from gbe@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4By4yb2sszz44wD; Thu, 24 Sep 2020 19:35:35 +0000 (UTC) (envelope-from gbe@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 466F0271F4; Thu, 24 Sep 2020 19:35:35 +0000 (UTC) (envelope-from gbe@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 08OJZZMP050743; Thu, 24 Sep 2020 19:35:35 GMT (envelope-from gbe@FreeBSD.org) Received: (from gbe@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 08OJZZGs050742; Thu, 24 Sep 2020 19:35:35 GMT (envelope-from gbe@FreeBSD.org) Message-Id: <202009241935.08OJZZGs050742@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: gbe set sender to gbe@FreeBSD.org using -f From: Gordon Bergling Date: Thu, 24 Sep 2020 19:35:35 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r366128 - head/share/man/man4 X-SVN-Group: head X-SVN-Commit-Author: gbe X-SVN-Commit-Paths: head/share/man/man4 X-SVN-Commit-Revision: 366128 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 Sep 2020 19:35:35 -0000 Author: gbe (doc committer) Date: Thu Sep 24 19:35:34 2020 New Revision: 366128 URL: https://svnweb.freebsd.org/changeset/base/366128 Log: Add missing file (tcp_bbr.4) from r366127 Reviewed by: bcr Approved by: bcr Differential Revision: https://reviews.freebsd.org/D24915 Added: head/share/man/man4/tcp_bbr.4 (contents, props changed) Added: head/share/man/man4/tcp_bbr.4 ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ head/share/man/man4/tcp_bbr.4 Thu Sep 24 19:35:34 2020 (r366128) @@ -0,0 +1,168 @@ +.\" +.\" Copyright (c) 2020, Gordon Bergling +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR +.\" ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd September 24, 2020 +.Dt TCP_BBR 4 +.Os +.Sh NAME +.Nm tcp_bbr +.Nd TCP Bottleneck Bandwidth and Round-Trip Time Algorithm +.Sh SYNOPSIS +To use this TCP stack you have to place the following line in your +kernel configuration file: +.Bd -ragged -offset indent +.Cd "options TCPHPTS" +.Ed +.Pp +To load the driver as a module at boot time, place the following line in +.Xr loader.conf 5 : +.Bd -literal -offset indent +tcp_bbr_load="YES" +.Ed +.Pp +To enable the TCP stack you must place the following line in the +.Xr sysctl.conf 5 : +.Bd -literal -offset indent +net.inet.tcp.functions_default=bbr +.Ed +.Sh DESCRIPTION +Bottleneck bandwidth and round-trip time (BBR) is a congestion control algorithm which +seeks high throughput with a small queue by probing BW and RTT. +It is a round-up redesign of congestion control, which is not loss-based, delay-based, +ECN-based or AIMD-based. +.Pp +The core design of BBR is about creating a model graph of the network path by +estimating the maximum BW and minimum RTT on each ACK. +.Sh MIB Variables +The algorithm exposes the following scopes in the +.Va net.inet.tcp.bbr +branch of the +.Xr sysctl 3 +MIB: +.Bl -tag -width ".Va exp_backoff_scale" +.It Va cwnd +Cwnd controls, for example "target cwnd rtt measurment" and "BBR initial window". +.It Va measure +Measurement controls. +.It Va pacing +Connection pacing controls. +.It Va policer +Policer controls, for example "false detection threshold" and "loss threshold". +.It Va probertt +Probe RTT controls. +.It Va startup +Startup controls. +.It Va states +State controls. +.It Va timeout +Time out controls. +.El +.Pp +Besides the variables within the above scopes the following +variables are also exposed in the +.Va net.inet.tcp.bbr +branch: +.Bl -tag -width ".Va exp_backoff_scale" +.It Va clrlost +Clear lost counters. +.It Va software_pacing +Total number of software paced flows. +.It Va hdwr_pacing +Total number of hardware paced flows. +.It Va enob_no_hdwr_pacing +Total number of enobufs for non-hardware paced flows. +.It Va enob_hdwr_pacing +Total number of enobufs for hardware paced flows. +.It Va rtt_tlp_thresh +What divisor for TLP rtt/retran will be added (1=rtt, 2=1/2 rtt etc). +.It Va reorder_fade +Does reorder detection fade, if so how many ms (0 means never). +.It Va reorder_thresh +What factor for rack will be added when seeing reordering (shift right). +.It Va bb_verbose +Should BBR black box logging be verbose. +.It Va sblklimit +When do we start ignoring small sack blocks. +.It Va resend_use_tso +Can resends use TSO? +.It Va data_after_close +Do we hold off sending a RST until all pending data is ack'd. +.It Va kill_paceout +When we hit this many errors in a row, kill the session? +.It Va error_paceout +When we hit an error what is the min to pace out in usec's? +.It Va cheat_rxt +Do we burst 1ms between sends on retransmissions (like rack)? +.It Va minrto +Minimum RTO in ms. +.El +.Sh SEE ALSO +.Xr cc_chd 4 , +.Xr cc_cubic 4 , +.Xr cc_hd 4 , +.Xr cc_htcp 4 , +.Xr cc_newreno 4 , +.Xr cc_vegas 4 , +.Xr h_ertt 4 , +.Xr mod_cc 4 , +.Xr tcp 4 , +.Xr mod_cc 9 +.Rs +.%A "Neal Cardwell" +.%A "Yuchung Cheng" +.%A "Stephen Gunn" +.%A "Soheil Hassas Yeganeh" +.%A "Van Jacobson" +.%T "BBR: Congestion-Based Congestion Control" +.%J "ACM Queue, Vol. 14" +.%D "September / October 2016" +.Re +.Rs +.%A "Dominik Scholz" +.%A "Benedikt Jaeger" +.%A "Lukas Schwaighofer" +.%A "Daniel Raumer" +.%A "Fabien Geyer" +.%A "Georg Carle" +.%T "Towards a Deeper Understanding of TCP BBR Congestion Control" +.%J "IFIP Networking 2018" +.%D "May 2018" +.%U "http://www.net.in.tum.de/fileadmin/bibtex/publications/papers/IFIP-Networking-2018-TCP-BBR.pdf" +.Re +.Sh HISTORY +The +.Nm +congestion control module first appeared in +.Fx 13.0 . +.Sh AUTHORS +.An -nosplit +The +.Nm +congestion control module was written by +.An Randall Stewart Aq Mt rrs@FreeBSD.org +and sponsored by Netflix, Inc. +This manual page was written by +.An Gordon Bergling Aq Mt gbe@FreeBSD.org .