On 28.10.2012 18:30, Andre Oppermann wrote:
Author: andre
Date: Sun Oct 28 17:30:28 2012
New Revision: 242251
URL: http://svn.freebsd.org/changeset/base/242251
Log:
When SYN or SYN/ACK had to be retransmitted RFC5681 requires us to
reduce the initial CWND to one segment. This reduction got lost
some time ago due to a change in initialization ordering.
Additionally in tcp_timer_rexmt() avoid entering fast recovery when
we're still in TCPS_SYN_SENT state.
Oops, this was the wrong commit message for this change. Here is the
correct one:
Defer sending an independent window update if a delayed ACK is pending
saving a packet. The window update then gets piggy-backed on the next
already scheduled ACK.
I've forced commit r242311 with some grammar fixes to provide this information.
--
Andre
MFC after: 2 weeks
Modified:
head/sys/netinet/tcp_output.c
Modified: head/sys/netinet/tcp_output.c
==
--- head/sys/netinet/tcp_output.c Sun Oct 28 17:25:08 2012
(r242250)
+++ head/sys/netinet/tcp_output.c Sun Oct 28 17:30:28 2012
(r242251)
@@ -551,10 +551,14 @@ after_sack_rexmit:
* max size segments, or at least 50% of the maximum possible
* window, then want to send a window update to peer.
* Skip this if the connection is in T/TCP half-open state.
-* Don't send pure window updates when the peer has closed
-* the connection and won't ever send more data.
+*
+* Don't send an independent window update if a delayed
+* ACK is pending (it will get piggy-backed on it) or the
+* remote side already has done a half-close and won't send
+* more data.
*/
if (recwin 0 !(tp-t_flags TF_NEEDSYN)
+ !(tp-t_flags TF_DELACK)
!TCPS_HAVERCVDFIN(tp-t_state)) {
/*
* adv is the amount we can increase the window,
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