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RTO connection timeout: sysctl documentation update 

This patch updates the sysctl documentation concerning the interpretation
of tcp_retries{1,2} and tcp_orphan_retries.

Signed-off-by: Damian Lukowski <damian@tvk.rwth-aachen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Damian Lukowski 2009-09-01 10:24:04 +00:00 committed by David S. Miller
parent 5152fc7de3
commit 5d7892298a
1 changed files with 26 additions and 11 deletions
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37
Documentation/networking/ip-sysctl.txt
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@ -311,9 +311,12 @@ tcp_no_metrics_save - BOOLEAN
connections.
tcp_orphan_retries - INTEGER
How may times to retry before killing TCP connection, closed
by our side. Default value 7 corresponds to ~50sec-16min
depending on RTO. If you machine is loaded WEB server,
This value influences the timeout of a locally closed TCP connection,
when RTO retransmissions remain unacknowledged.
See tcp_retries2 for more details.
The default value is 7.
If your machine is a loaded WEB server,
you should think about lowering this value, such sockets
may consume significant resources. Cf. tcp_max_orphans.
@ -327,16 +330,28 @@ tcp_retrans_collapse - BOOLEAN
certain TCP stacks.
tcp_retries1 - INTEGER
How many times to retry before deciding that something is wrong
and it is necessary to report this suspicion to network layer.
Minimal RFC value is 3, it is default, which corresponds
to ~3sec-8min depending on RTO.
This value influences the time, after which TCP decides, that
something is wrong due to unacknowledged RTO retransmissions,
and reports this suspicion to the network layer.
See tcp_retries2 for more details.
RFC 1122 recommends at least 3 retransmissions, which is the
default.
tcp_retries2 - INTEGER
How may times to retry before killing alive TCP connection.
RFC1122 says that the limit should be longer than 100 sec.
It is too small number. Default value 15 corresponds to ~13-30min
depending on RTO.
This value influences the timeout of an alive TCP connection,
when RTO retransmissions remain unacknowledged.
Given a value of N, a hypothetical TCP connection following
exponential backoff with an initial RTO of TCP_RTO_MIN would
retransmit N times before killing the connection at the (N+1)th RTO.
The default value of 15 yields a hypothetical timeout of 924.6
seconds and is a lower bound for the effective timeout.
TCP will effectively time out at the first RTO which exceeds the
hypothetical timeout.
RFC 1122 recommends at least 100 seconds for the timeout,
which corresponds to a value of at least 8.
tcp_rfc1337 - BOOLEAN
If set, the TCP stack behaves conforming to RFC1337. If unset,