Sorry but this is not a bug. You set bad sysctl flags. We won't add it to our database and this is the final decison.
Regards, Freebsd Team On Fri, Aug 6, 2010 at 10:56 AM, Andre Oppermann <an...@freebsd.org> wrote: > On 13.07.2010 16:01, Maxim Dounin wrote: >> >> Hello! >> >> On Wed, May 12, 2010 at 04:47:02PM +0400, Igor Sysoev wrote: >> >>> It seems that net.inet.tcp.slowstart_flightsize does not work in >>> 8-STABLE. >>> For a long time I used slowstart_flightsize=2 on FreeBSD 4, 6, and 7 >>> hosts. >>> However, FreeBSD-8 always starts with the single packet. >>> I saw this on different versions of 8-STABLE since 8 Oct 2009 till >>> 04 Apr 2010. >> >> Finally I had some time to look into it (sorry for long delay). >> >> 1. Slow start isn't used on recent FreeBSD versions for initial snd_cwnd >> calculations as long as you have rfc3390 support switched on (default >> since >> Jan 06 23:29:46 2004, at least in 7.*). It effectively sets initial >> snd_cwnd to 3*MSS on common networks and shouldn't cause any problems. >> Slowstart_flightsize only affects connection restarts. >> >> 2. Due to bug in syncache code (patch below) all accepted connections has >> their snd_cwnd reset to 1*MSS (since r171639, 7.0+ AFAIR). >> >> 3. Support for rfc3465 introduced in r187289 uncovered (2) as >> ACK to SYN/ACK no longer causes snd_cwnd increase by MSS (actually, this >> increase shouldn't happen as it's explicitly forbidden by rfc 3390, but >> it's another issue). Snd_cwnd remains really small (1*MSS + 1) and this >> causes really bad interaction with delayed acks on other side. >> >> As a workaround to delayed acks interaction problems you may disable >> rfc3465 by setting net.inet.tcp.rfc3465 to 0. Correct fix would be to >> apply >> the patch below. >> >> To Andre Oppermann: could you please take a look at the patch and >> commit it if found appropriate? > > I've committed your fix with svn r210666. In a few days I will MFC it back > to the stable branches. Thanks for reporting the bug and a patch for it. > > -- > Andre > >> # HG changeset patch >> # User Maxim Dounin<mdou...@mdounin.ru> >> # Date 1279028684 -14400 >> # Node ID 93699203f408fa8e22c971769bde9c26bd14d410 >> # Parent e2cf8c51a6294a0d09d5628d96c6ab3ab626957e >> Fix cwnd resetting problem introduced in r171639. >> >> Sc_rxmits counts timer engagements, not actual retransmits, and value 1 >> corresponds to no retransmits. Revert check to correct one as present >> before r171639. >> >> diff --git a/netinet/tcp_syncache.c b/netinet/tcp_syncache.c >> --- a/netinet/tcp_syncache.c >> +++ b/netinet/tcp_syncache.c >> @@ -804,8 +804,10 @@ syncache_socket(struct syncache *sc, str >> >> /* >> * If the SYN,ACK was retransmitted, reset cwnd to 1 segment. >> + * Note that sc_rxmits counts timer engagements, not actual >> + * retransmits. >> */ >> - if (sc->sc_rxmits) >> + if (sc->sc_rxmits> 1) >> tp->snd_cwnd = tp->t_maxseg; >> tcp_timer_activate(tp, TT_KEEP, tcp_keepinit); >> >> >> Maxim Dounin >> _______________________________________________ >> freebsd-net@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-net >> To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org" >> >> > > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org" > _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
