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Re: Why is my gigabit ethernet so slow?

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 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 ( ). 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...


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