svn commit: r184153 - in projects/tcp_cc_7.x/sys: . netinet

[Lawrence Stewart]

Author: lstewart
Date: Wed Oct 22 07:21:02 2008
New Revision: 184153
URL: http://svn.freebsd.org/changeset/base/184153

Log:
  Merge r184152 from tcp_cc_8.x

Modified:
  projects/tcp_cc_7.x/sys/   (props changed)
  projects/tcp_cc_7.x/sys/netinet/cc.c
  projects/tcp_cc_7.x/sys/netinet/tcp_input.c

Modified: projects/tcp_cc_7.x/sys/netinet/cc.c
==============================================================================
--- projects/tcp_cc_7.x/sys/netinet/cc.c	Wed Oct 22 07:06:38 2008	(r184152)
+++ projects/tcp_cc_7.x/sys/netinet/cc.c	Wed Oct 22 07:21:02 2008	(r184153)
@@ -333,8 +333,15 @@ newreno_ack_received(struct tcpcb *tp, s
 	u_int cw = tp->snd_cwnd;
 	u_int incr = tp->t_maxseg;
 
+	/*
+	 * If cwnd <= ssthresh, open exponentially (maxseg per packet).
+	 * Otherwise, open linearly (approx. maxseg per RTT
+	 * i.e. maxseg^2 / cwnd per ACK received).
+	 * If cwnd > maxseg^2, fix the cwnd increment at 1 byte
+	 * to avoid capping cwnd (as suggested in RFC2581).
+	 */
 	if (cw > tp->snd_ssthresh)
-		incr = incr * incr / cw;
+		incr = max((incr * incr / cw), 1);
 
 	tp->snd_cwnd = min(cw+incr, TCP_MAXWIN<<tp->snd_scale);
 }

Modified: projects/tcp_cc_7.x/sys/netinet/tcp_input.c
==============================================================================
--- projects/tcp_cc_7.x/sys/netinet/tcp_input.c	Wed Oct 22 07:06:38 2008	(r184152)
+++ projects/tcp_cc_7.x/sys/netinet/tcp_input.c	Wed Oct 22 07:21:02 2008	(r184153)
@@ -2002,12 +2002,8 @@ process_ACK:
 
 		/*
 		 * When new data is acked, open the congestion window.
-		 * If the window gives us less than ssthresh packets
-		 * in flight, open exponentially (maxseg per packet).
-		 * Otherwise open linearly: maxseg per window
-		 * (maxseg^2 / cwnd per packet).
-		 * If cwnd > maxseg^2, fix the cwnd increment at 1 byte
-		 * to avoid capping cwnd (as suggested in RFC2581).
+		 * The specifics of how this is achieved are up to the
+		 * congestion control algorithm in use for this connection.
 		 */
 		if (!IN_FASTRECOVERY(tp)) {
 			if (CC_ALGO(tp)->ack_received)