From 650d7ce0608e898fd01562ae65d98f05d79203be Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Thu, 20 Nov 2008 17:04:39 -0500 Subject: [PATCH] tcp.7: Document /proc file tcp_mtu_probing (new in Linux 2.6.17) Text taken from Documentation/networking/ip-sysctl.txt Signed-off-by: Michael Kerrisk --- man7/tcp.7 | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/man7/tcp.7 b/man7/tcp.7 index fadfd41b7..2712e2811 100644 --- a/man7/tcp.7 +++ b/man7/tcp.7 @@ -435,14 +435,27 @@ will allocate. This value overrides any other limits imposed by the kernel. .TP +.IR tcp_mtu_probing " (integer; default: 0; since Linux 2.6.17)" +.\" The following is from 2.6.28-rc4: Documentation/networking/ip-sysctl.txt +This parameter controls TCP Packetization-Layer Path MTU Discovery. +The following values may be assigned to the file: +.RS +.IP 0 3 +Disabled +.IP 1 +Disabled by default, enabled when an ICMP black hole detected +.IP 2 +Always enabled, use initial MSS of +.IR tcp_base_mss . +.RE +.TP .IR tcp_no_metrics_save " (Boolean; default: disabled; since Linux 2.6.6)" .\" The following is from 2.6.28-rc4: Documentation/networking/ip-sysctl.txt By default, TCP saves various connection metrics in the route cache when the connection closes, so that connections established in the near future can use these to set initial conditions. Usually, this increases overall performance, -but it may sometimes cause performance -degradation. +but it may sometimes cause performance degradation. If .I tcp_no_metrics_save is enabled, TCP will not cache metrics on closing connections.