net.inet.tcp.slowstart_flightsize in 8-STABLE

[Maxim Dounin]

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.

Maxim Dounin