Be a bit more precisly in the description of the sysctl variable

net.inet.tcp.pmtud_blackhole_detection. Also remove three entries,
which are not sysctl variables but statistic counters for TCP.
Thanks to 0mp@ for suggesting an improvement.

Reviewed by:		bcr@
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D24216
This commit is contained in:
Michael Tuexen 2020-03-29 15:43:00 +00:00
parent 5292d0a7f3
commit 65c5bff387
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=359422

View File

@ -34,7 +34,7 @@
.\" From: @(#)tcp.4 8.1 (Berkeley) 6/5/93 .\" From: @(#)tcp.4 8.1 (Berkeley) 6/5/93
.\" $FreeBSD$ .\" $FreeBSD$
.\" .\"
.Dd December 2, 2019 .Dd March 29, 2020
.Dt TCP 4 .Dt TCP 4
.Os .Os
.Sh NAME .Sh NAME
@ -632,7 +632,12 @@ Turn on automatic path MTU blackhole detection.
In case of retransmits OS will In case of retransmits OS will
lower the MSS to check if it's MTU problem. lower the MSS to check if it's MTU problem.
If current MSS is greater than If current MSS is greater than
configured value to try, it will be set to configured value, otherwise, configured value to try
.Po Va net.inet.tcp.pmtud_blackhole_mss
and
.Va net.inet.tcp.v6pmtud_blackhole_mss
.Pc ,
it will be set to this value, otherwise,
MSS will be set to default values MSS will be set to default values
.Po Va net.inet.tcp.mssdflt .Po Va net.inet.tcp.mssdflt
and and
@ -642,13 +647,6 @@ and
MSS to try for IPv4 if PMTU blackhole detection is turned on. MSS to try for IPv4 if PMTU blackhole detection is turned on.
.It Va v6pmtud_blackhole_mss .It Va v6pmtud_blackhole_mss
MSS to try for IPv6 if PMTU blackhole detection is turned on. MSS to try for IPv6 if PMTU blackhole detection is turned on.
.It Va pmtud_blackhole_activated
Number of times configured values were used in an attempt to downshift.
.It Va pmtud_blackhole_activated_min_mss
Number of times default MSS was used in an attempt to downshift.
.It Va pmtud_blackhole_failed
Number of connections for which retransmits continued even after MSS
downshift.
.It Va functions_available .It Va functions_available
List of available TCP function blocks (TCP stacks). List of available TCP function blocks (TCP stacks).
.It Va functions_default .It Va functions_default