Date: Mon, 29 Oct 2012 14:18:09 +0100 From: Andre Oppermann <andre@freebsd.org> To: Andre Oppermann <andre@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r242251 - head/sys/netinet Message-ID: <508E8211.5020903@freebsd.org> In-Reply-To: <201210281730.q9SHUT6U062773@svn.freebsd.org> References: <201210281730.q9SHUT6U062773@svn.freebsd.org>
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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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