tcp: make CUBIC the default congestion control mechanism.

This changes the default TCP Congestion Control (CC) to CUBIC.
For small, transactional exchanges (e.g. web objects <15kB), this
will not have a material effect. However, for long duration data
transfers, CUBIC allocates a slightly higher fraction of the
available bandwidth, when competing against NewReno CC.

Reviewed By: tuexen, mav, #transport, guest-ccui, emaste
Relnotes: Yes
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D36537

3 files changed, 10 insertions, 10 deletions

diff --git a/share/man/man4/cc_cubic.4 b/share/man/man4/cc_cubic.4
index 806d6aec2441..9ceaaa871777 100644
--- a/share/man/man4/cc_cubic.4
+++ b/share/man/man4/cc_cubic.4
@@ -30,7 +30,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 13, 2021
+.Dd September 13, 2022
 .Dt CC_CUBIC 4
 .Os
 .Sh NAME
@@ -39,6 +39,7 @@
 .Sh DESCRIPTION
 The CUBIC congestion control algorithm was designed to provide increased
 throughput in fast and long-distance networks.
+The CUBIC congestion control algorithm is the default for TCP.
 It attempts to maintain fairness when competing with legacy NewReno TCP in lower
 speed scenarios where NewReno is able to operate adequately.
 .Pp
diff --git a/share/man/man4/cc_newreno.4 b/share/man/man4/cc_newreno.4
index 76dd3b2559bb..0d0f0d000d38 100644
--- a/share/man/man4/cc_newreno.4
+++ b/share/man/man4/cc_newreno.4
@@ -30,7 +30,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 13, 2021
+.Dd September 13, 2022
 .Dt CC_NEWRENO 4
 .Os
 .Sh NAME
@@ -39,7 +39,6 @@
 .Sh SYNOPSIS
 .In netinet/cc/cc_newreno.h
 .Sh DESCRIPTION
-The NewReno congestion control algorithm is the default for TCP.
 Details about the algorithm can be found in RFC5681.
 .Sh Socket Options
 The
diff --git a/share/man/man4/mod_cc.4 b/share/man/man4/mod_cc.4
index a00f17ede5e4..a03ff0630c15 100644
--- a/share/man/man4/mod_cc.4
+++ b/share/man/man4/mod_cc.4
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 6, 2019
+.Dd September 13, 2022
 .Dt MOD_CC 4
 .Os
 .Sh NAME
@@ -47,7 +47,7 @@ using the
 .Xr kld 4
 facility.
 .Pp
-The default algorithm is NewReno, and all connections use the default unless
+The default algorithm is CUBIC, and all connections use the default unless
 explicitly overridden using the
 .Dv TCP_CONGESTION
 socket option (see
@@ -127,7 +127,7 @@ For further explanation please see the internet-draft.
 .Pp
 Each congestion control module may also expose other MIB variables
 to control their behaviour.
-Note that both newreno and cubic now support hystart++ based on the version 3 of the internet-draft.
+Note that both NewReno and CUBIC now support Hystart++ based on the version 3 of the internet-draft.
 .Sh Kernel Configuration
 All of the available congestion control modules may also be loaded
 via kernel configutation options.
@@ -138,10 +138,10 @@ Compilation of the kernel will fail if these two conditions are not met.
 The framework exposes the following kernel configuration options.
 .Bl -tag -width ".Va CC_NEWRENO"
 .It Va CC_NEWRENO
-This directive loads the newreno congestion control algorithm and is included
-in GENERIC by default.
+This directive loads the NewReno congestion control algorithm.
 .It Va CC_CUBIC
-This directive loads the cubic congestion control algorithm.
+This directive loads the CUBIC congestion control algorithm and is included
+in GENERIC by default.
 .It Va CC_VEGAS
 This directive loads the vegas congestion control algorithm, note that
 this algorithm also requires the TCP_HHOOK option as well.
@@ -160,7 +160,7 @@ this algorithm also requires the TCP_HHOOK option as well.
 This directive loads the htcp congestion control algorithm.
 .It Va CC_DEFAULT
 This directive specifies the string that represents the name of the system default algorithm, the GENERIC kernel
-defaults this to newreno.
+defaults this to CUBIC.
 .El
 .Sh SEE ALSO
 .Xr cc_cdg 4 ,