Re: hpn_buffer_size

[Petar Bogdanovic <petar%smokva.net@localhost>]

On Fri, Apr 27, 2012 at 11:17:40AM -0700, Chuck Swiger wrote:
> On Apr 27, 2012, at 11:10 AM, Petar Bogdanovic wrote:
> > I'm trying to figure out, why two nearly identical netbsd-6 hosts have
> > troubles using hpn.  They are connected through a 5000 Kb/s link and the
> > following (not very scientific) test:
> > 
> >     dd if=FILE bs=1m count=2 | ssh HOST dd bs=64k of=/dev/null
> > 
> > yields different results when defaults are in place (430KB/s) and when
> > HPNDisabled=yes and/or HPNBufferSize=2048 (590KB/s).
> 
> You need to increase the TCP window size to take significant advantage
> of the SSH HPN changes.  Take a look at the following sysctls:
> 
> kern.sbmax
> net.inet.tcp.rfc1323
> net.inet.tcp.recvbuf_max
> net.inet.tcp.sendbuf_max
> net.inet.tcp.recvspace
> net.inet.tcp.sendspace
> 
> You'll also need to increase NMBCLUSTERS, unless that has become
> a sysctl tunable as well...

Thanks for the hints but I'm not sure I understand the logic behind
this.  HPNDisabled=no is the default setting, and I'm not running high
powered n Gigabit-Interfaces so why should a default setting in a rather
unspectacular environment require any additional tweaking?

Or in other words: Wouldn't a HPNDisabled=yes default make more sense?