Re: 923Mbits/s across the ocean

["David G. Andersen" <dga () lcs mit edu>]

On Sun, Mar 09, 2003 at 02:25:25PM +0100, Iljitsch van Beijnum quacked:
> On Sat, 8 Mar 2003, Joe St Sauver wrote:
>
> > you will see that for bulk TCP flows, the median throughput is still only
> > 2.3Mbps. 95th%-ile is only ~9Mbps. That's really not all that great,
> > throughput wise, IMHO.
>
> Strange. Why is that? RFC 1323 is widely implemented, although not
> widely enabled (and for good reason: the timestamp option kills header
> compression so it's bad for lower-bandwidth connections). My guess is
> that the OS can't afford to throw around MB+ size buffers for every TCP
> session so the default buffers (which limit the windows that can be
> used) are relatively small and application programmers don't override
> the default.

  Which makes it doubly a shame that the adaptive buffer tuning
tricks haven't made it into production systems yet.  It was
a beautiful, simple idea that worked very well for adapting to
long fat networks:

  http://www.acm.org/sigcomm/sigcomm98/tp/abs_26.html

  -dave

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