Arg. TCP slow start killing me.

[Matt Connor]

On 13.11.2011 17:45, Julian Elischer wrote:
> On 11/13/11 4:22 PM, Erich Weiler wrote:
>>> Yeah, skimming fail, I didn't realize the machine was not the
>>> termination point of your connections.  I do have patches back 
>>> ported
>>> that would likely get the modular congestion control working on 
>>> 8.1,
>>> but neither my suggestions nor the implementation of Cubic will 
>>> help
>>> much as mentioned.
>>
>> Given that my firewall is simply forwarding packets in and out, and 
>> is not an endpoint, does anyone think tuning up buffers would help 
>> here? If so, which buffers/sysctl parameters would be worth trying?
>
> I can not answer abut pf but I'll say that if I were using ipfw I
> would use dummynet to rate linit the speed that the incoming packets
> were passed on to the client macjines and I would make that limit 
> just
> alittle slower than the incoming link's real speed.
> that way the linit would be In my machine instead of in my ISPs 
> machines.
>
> If pf has a similar mechanism to dummy net then you may be able to 
> try that.
>

Have you considered empty ACK prioritization? I implemented this a year 
ago on a pair of production edge routers and noticed significant 
improvement on throughput. I have production code examples if you 
require them, but this link should be more than enough to get you 
started:

http://www.benzedrine.cx/ackpri.html

-Matt