Very high wide area TCP tuning

[Isaac Kohen]

I've sent several messages to "freebsd-net-unsubscribe at freebsd.org" and I'm
still receiving messages. How do I stop this?

On 8/13/07, Lawrence Stewart <lstewart at room52.net> wrote:
>
> Hi Kevin,
>
> Kevin Oberman wrote:
> > I am attempting to use a FreeBSD box with either a Myricom or Chelsio
> > 10GE card to generate very large TCP streams over cross-country
> > links. The RTT for the test path is 94 ms. It is dedicated to my testing
> > at this time, so I have no contention other than a few KB of routing
> > updates.
> >
> > Clearly, I need a very large window...about 120 MB, but I am unsure how
> > FreeBSD will handle this. (Unless I do other things, I suspect it will
> > not be pretty.) I imagine I will need a large kvm space, at the least,
> > but are there any other sysctls that are likely to need adjusting to
> > make this all work? IS it likely to work better on a amd64 system than a
> > i386?
> >
> > Any suggestions would be appreciated.
> >
>
> We recently wrote a small technical report that covers some of the
> issues related to FreeBSD network tuning for some TCP research we've
> been doing.
>
> The report's title is "Tuning and Testing the FreeBSD 6 TCP Stack" and
> you can grab it from here:
> http://caia.swin.edu.au/reports/070717B/CAIA-TR-070717B.pdf
>
> We didn't tune for 10GB speeds, but I imagine the principles should all
> still apply. As you correctly point out, you'll also probably want to
> raise the allowable kernel mem size using the "vm.kmem_size" and
> "vm.kmem_size_max" sysctls to avoid any random kernel panics. We used a
> kmem size of 500MB which worked flawlessly with our GigE multiflow tests
> and left us plenty of room to move. This is something you might have to
> use a bit of trial and error to figure out though to ensure you get
> something stable. And of course you're going to want to control the
> number of flows active at one time based on your kmem setting and
> hardware constraints...
>
> Cheers,
> Lawrence
>
> http://caia.swin.edu.au
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