Latency, TCP ACKs and upload needs

Eygene Ryabinkin rea+nanog at
Fri Apr 22 06:17:54 UTC 2016

Wed, Apr 20, 2016 at 07:27:53AM -0700, Leo Bicknell wrote:
> 90%+ of the stacks deployed will be too small.  Modern Unix generally
> has "autotuning" TCP stacks, but I don't think Windows or OS X has
> those features yet

OS X since ~10.5 has autotuning, here are some hints from ESnet
Personally never tried this on the sat-type RTT.  As explained,
scaling factor of 3 is a limiting one for high-performance transfers.
For sat links may limit the things too, since 64K * 2^3 / 0.9 ms RTT * 8 ~
4.5 Mbit/sec, but one's mileage may vary.  And, of course, packet loss
can turn down this BDP-derived speed drastically.
Eygene Ryabinkin, National Research Centre "Kurchatov Institute"

Always code as if the guy who ends up maintaining your code will be
a violent psychopath who knows where you live.
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