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Re: Increase tcp initial window

Loganaden Velvindron <> wrote on Sat, 30 
Mar 2013
at 01:44:00 -0400 in <>:

> It seems to be getting a lot of revisions. Other BSDs have also
> implemented it.

Loganaden, Greg's criticism is of making the parameter entirely tunable.
In a fashion that would allow an ignorant user to set an initial
window of not just 10, but also 20, 40, 50, 100.

Are you saying that other BSDs permit that?

> > [1] Yes, I get it that users can rebuild their kernels to do arbitrary
> > things.  Partly this is about not helping people without adequate
> > technical skill to violate internet norms, and partly it's about setting
> > expectations.
> Maybe we should try to do the some empirical measurements to see if it has
> too many side effects.

The problem is what happens when large numbers of people in the
Internet do this. This is why the research community has been very
careful to propose changes to this parameter quite slowly.

> What about putting this as a sysctl and document it properly as christos and
> matt suggested ?

That misses Greg's point -- that allowing users this flexibility is
not generally regarded as safe, and is indeed quite scary.

We could allow tunability within some restricted range, as a
compromise, but even that, I think is unwise. Those with the requisite
skill to understand this parameter in the context of its effect on the
broader Internet also have the requisite skill to rebuild their kernels
(or patch them live!).
  John Hawkinson

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