Re: hpn_buffer_size

[Chuck Swiger <cswiger%mac.com@localhost>]

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...

Regards,
-- 
-Chuck