- Estimate the amount of data in flight in sack recovery and use it

  to control the packets injected while in sack recovery (for both
  retransmissions and new data).
- Cleanups to the sack codepaths in tcp_output.c and tcp_sack.c.
- Add a new sysctl (net.inet.tcp.sack.initburst) that controls the
  number of sack retransmissions done upon initiation of sack recovery.

Submitted by:	Mohan Srinivasan <mohans@yahoo-inc.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 3b70e99..b96b959 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -155,6 +155,12 @@ SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
 	   &tcp_reass_overflows, 0,
 	   "Global number of TCP Segment Reassembly Queue Overflows");
 
+static int tcp_sack_recovery_initburst = 3;
+SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO,
+	   initburst, CTLFLAG_RW,
+	   &tcp_sack_recovery_initburst, 0,
+	   "Initial Number of Rexmits when sack recovery is set up");
+
 struct inpcbhead tcb;
 #define	tcb6	tcb  /* for KAME src sync over BSD*'s */
 struct inpcbinfo tcbinfo;
@@ -1980,9 +1986,9 @@ trimthenstep6:
 					tp->t_rtttime = 0;
 					if (tp->sack_enable) {
 						tcpstat.tcps_sack_recovery_episode++;
-						tp->snd_cwnd =
-						    tp->t_maxseg *
-						    tp->t_dupacks;
+						tp->sack_newdata = tp->snd_nxt;
+						tp->snd_cwnd = 
+							tp->t_maxseg * tcp_sack_recovery_initburst;
 						(void) tcp_output(tp);
 						tp->snd_cwnd +=
 						    tp->snd_ssthresh;