Re: Why is my gigabit ethernet so slow?

[Fredrik Pettai <pettai%nordu.net@localhost>]

On Jan 27, 2010, at 7:48 PM, Thor Lancelot Simon wrote:
> On Wed, Jan 27, 2010 at 02:44:29PM +0200, Martti Kuparinen wrote:
> > I found http://proj.sunet.se/E2E/tcptune.html and played a little  
> > with
> > the receiver (NetBSD 5.99.24), below 3 runs with both settings. The
> > conclusion is that I'm happy now as I'm able to route 850+ Mbps  
> > through
> > my router...
>
> Changing the initial window is highly antisocial.  It's certainly not
> good general-purpose advice for tuning TCP stacks and it's probably  
> not
> necessary to get the throughput you're looking for.

That was done a long time a ago with the goal and sole purpose to  
break the Internet land speed record (http://proj.sunet.se/LSR2/index.html 
).
Note, SUNET used iNTEL 10GbE prototype cards for this, and those card  
doesn't perform very well with NetBSD today.

However, while testing those old prototype cards and some other NICs  
for speed with NetBSD 5.0 RC...  we found that turning of sack would  
increase throughput performance.

# Disable SACK, buggy with dge(4) 10GbE-LR?
sysctl -w net.inet.tcp.sack.enable=0
sysctl -w net.inet6.tcp6.sack.enable=0

I don't think anyone investigated it further to conclude if it where  
the NIC or the NetBSD code that was buggy.
You might give it a try and see what happens...

Regards,
/P