Commit 746aa32d authored Nov 13, 2007 by Ilpo Jrvinen Committed by David S. Miller Nov 13, 2007

[TCP] FRTO: Limit snd_cwnd if TCP was application limited



Otherwise TCP might violate packet ordering principles that FRTO
is based on. If conventional recovery path is chosen, this won't
be significant at all. In practice, any small enough value will
be sufficient to provide proper operation for FRTO, yet other
users of snd_cwnd might benefit from a "close enough" value.

FRTO's formula is now equal to what tcp_enter_cwr() uses.

FRTO used to check application limitedness a bit differently but
I changed that in commit 575ee714
and as a result checking for application limitedness became
completely non-existing.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent f0163ac4

net/ipv4/tcp_input.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1669,6 +1669,9 @@ void tcp_enter_frto(struct sock *sk)
		}
		tcp_verify_left_out(tp);

		/* Too bad if TCP was application limited */
		tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp) + 1);

		/* Earlier loss recovery underway (see RFC4138; Appendix B).
		* The last condition is necessary at least in tp->frto_counter case.
		*/

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