On Wed, 15 Jul 2009, zaheer ahmad wrote:

> - how to determine the optimal value?

I don't know.

> are there known techniques like using some sliding window?

How can a buffer size be a sliding window?

> - if the optimal value is dynamic, why is not taken care transparently in
> curl

Is it dynamic? If you find out it is, you're more than welcome to present
those results to us!

And the answer to most "whys" is of course that someone has to figure out if
that is the case, and then write a decent implementation that acts
accordingly.

> - why do we see a drop in performance after a peak increase in buffer size
> - what factors would it depend on (network MTU, current network speed,
> servers)

I would expect that to be good questions to someone with a fine insight on the
inner workings of the TCP/IP stack you use. I would also assume that it will
vary between implementations.

-- 
  / daniel.haxx.se