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Remove outdated reference to tcp inflight limiting. It was removed

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a long time ago.

MFC after:	1 week
This commit is contained in:
Andre Oppermann 2012-12-08 21:03:14 +00:00
parent b731376e8c
commit 4504d0f482
1 changed files with 1 additions and 47 deletions
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48
share/man/man7/tuning.7
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@ -23,7 +23,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd October 20, 2012
.Dd December 8, 2012
.Dt TUNING 7
.Os
.Sh NAME
@ -459,52 +459,6 @@ the
sysctl rather than disable delayed acks.
.Pp
The
.Va net.inet.tcp.inflight.enable
sysctl turns on bandwidth delay product limiting for all TCP connections.
The system will attempt to calculate the bandwidth delay product for each
connection and limit the amount of data queued to the network to just the
amount required to maintain optimum throughput.
This feature is useful
if you are serving data over modems, GigE, or high speed WAN links (or
any other link with a high bandwidth*delay product), especially if you are
also using window scaling or have configured a large send window.
If you enable this option, you should also be sure to set
.Va net.inet.tcp.inflight.debug
to 0 (disable debugging), and for production use setting
.Va net.inet.tcp.inflight.min
to at least 6144 may be beneficial.
Note however, that setting high
minimums may effectively disable bandwidth limiting depending on the link.
The limiting feature reduces the amount of data built up in intermediate
router and switch packet queues as well as reduces the amount of data built
up in the local host's interface queue.
With fewer packets queued up,
interactive connections, especially over slow modems, will also be able
to operate with lower round trip times.
However, note that this feature
only affects data transmission (uploading / server-side).
It does not
affect data reception (downloading).
.Pp
Adjusting
.Va net.inet.tcp.inflight.stab
is not recommended.
This parameter defaults to 20, representing 2 maximal packets added
to the bandwidth delay product window calculation.
The additional
window is required to stabilize the algorithm and improve responsiveness
to changing conditions, but it can also result in higher ping times
over slow links (though still much lower than you would get without
the inflight algorithm).
In such cases you may
wish to try reducing this parameter to 15, 10, or 5, and you may also
have to reduce
.Va net.inet.tcp.inflight.min
(for example, to 3500) to get the desired effect.
Reducing these parameters
should be done as a last resort only.
.Pp
The
.Va net.inet.ip.portrange.*
sysctls control the port number ranges automatically bound to TCP and UDP
sockets.