From 746aa32d280084dbd520249170852e4616799928 Mon Sep 17 00:00:00 2001 From: Ilpo Järvinen Date: Tue, 13 Nov 2007 21:01:23 -0800 Subject: [TCP] FRTO: Limit snd_cwnd if TCP was application limited MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 575ee7140dabe9b9c4f66f4f867039b97e548867 and as a result checking for application limitedness became completely non-existing. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 20c9440ab85e..b59da5308ac0 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -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. */ -- cgit v1.2.3