diff options
authorIlpo Järvinen <ilpo.jarvinen@helsinki.fi>2007-02-27 10:10:55 -0800
committerDavid S. Miller <davem@sunset.davemloft.net>2007-04-25 22:23:24 -0700
commit89808060b7a71376cc2ba8092d43b2010da465b6 (patch)
parent[TCP]: Add two new spurious RTO responses to FRTO (diff)
[TCP] Sysctl documentation: tcp_frto_response
In addition, fixed minor things in tcp_frto sysctl. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 19 insertions, 2 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 719b42907314..054c515bd726 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -179,15 +179,32 @@ tcp_fin_timeout - INTEGER
because they eat maximum 1.5K of memory, but they tend
to live longer. Cf. tcp_max_orphans.
-tcp_frto - BOOLEAN
+tcp_frto - INTEGER
Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
timeouts. It is particularly beneficial in wireless environments
where packet loss is typically due to random radio interference
rather than intermediate router congestion. If set to 1, basic
- version is enabled. 2 enables SACK enhanced FRTO, which is
+ version is enabled. 2 enables SACK enhanced F-RTO, which is
EXPERIMENTAL. The basic version can be used also when SACK is
enabled for a flow through tcp_sack sysctl.
+tcp_frto_response - INTEGER
+ When F-RTO has detected that a TCP retransmission timeout was
+ spurious (i.e, the timeout would have been avoided had TCP set a
+ longer retransmission timeout), TCP has several options what to do
+ next. Possible values are:
+ 0 Rate halving based; a smooth and conservative response,
+ results in halved cwnd and ssthresh after one RTT
+ 1 Very conservative response; not recommended because even
+ though being valid, it interacts poorly with the rest of
+ Linux TCP, halves cwnd and ssthresh immediately
+ 2 Aggressive response; undoes congestion control measures
+ that are now known to be unnecessary (ignoring the
+ possibility of a lost retransmission that would require
+ TCP to be more cautious), cwnd and ssthresh are restored
+ to the values prior timeout
+ Default: 0 (rate halving based)
tcp_keepalive_time - INTEGER
How often TCP sends out keepalive messages when keepalive is enabled.
Default: 2hours.