From ef2e1c3983d66891d6f6647432438ab07b505141 Mon Sep 17 00:00:00 2001 From: gbe Date: Thu, 24 Sep 2020 19:35:34 +0000 Subject: [PATCH] Add missing file (tcp_bbr.4) from r366127 Reviewed by: bcr Approved by: bcr Differential Revision: https://reviews.freebsd.org/D24915 --- share/man/man4/tcp_bbr.4 | 168 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 168 insertions(+) create mode 100644 share/man/man4/tcp_bbr.4 diff --git a/share/man/man4/tcp_bbr.4 b/share/man/man4/tcp_bbr.4 new file mode 100644 index 00000000000..ea7e436b6c5 --- /dev/null +++ b/share/man/man4/tcp_bbr.4 @@ -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 . -- 2.45.0