net.inet.tcp.slowstart_flightsize in 8-STABLE

Maxim Dounin mdounin at mdounin.ru
Tue Nov 2 00:11:37 UTC 2010


Hello!

On Mon, Sep 27, 2010 at 03:17:59PM +0200, Andre Oppermann wrote:

> On 27.09.2010 10:12, Maxim Dounin wrote:
> >Hello!
> >
> >On Mon, Sep 13, 2010 at 09:24:53PM +0400, Maxim Dounin wrote:
> >
> >[...]
> >
> >>Andre, could you please take a look at one more patch as well?
> >>
> >>Igor reported that it still sees 100ms delays with rfc3465 turned
> >>on, and it turns out to be similar issue (setting cwnd to 1*MSS)
> >>for hosts found in hostcache.
> >>
> >>The problem with setting cwnd from hostcache was already reported
> >>here:
> >>
> >>http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/92690
> >>http://lists.freebsd.org/pipermail/freebsd-net/2007-July/014780.html
> >>
> >>As using larger cwnd from hostcache may cause problems on
> >>congested links (see second thread) I changed code to only use
> >>cached cwnd as an upper bound for cwnd (instead of fixing current
> >>code).  This is also in-line with what we do on connection
> >>restarts.
> >>
> >>We may later consider re-adding usage of larger cwnd from
> >>hostcache.  But I believe it should be done carefully and
> >>probably behind sysctl, off by default.
> >
> >Ping.
> 
> Thanks for the reminder.  I'll disable priming CWND from hostcache.

Ping again.

I would like to see the patch in question[1] committed and MFC'ed 
somewhere before 8.2.

Andre, if you are just too busy to do it yourself - please say so, 
I'll ask somebody else to commit it.

[1] http://lists.freebsd.org/pipermail/freebsd-net/2010-September/026418.html

Maxim Dounin


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