[Bloat] What is wrong with Microsoft's receive window auto-tuning?

[Eric Dumazet]

On Mon, 2014-09-01 at 13:23 -0400, Jerry Jongerius wrote:
> I am noticing (via WireShark traces) at times that Microsoft's (Windows 7)
> receive window auto-tuning goes horribly wrong, causing significant buffer
> bloat.  And at other times, the tuning appears to work just fine.
> 
> For example, BDP suggests a receive window of 750k, and most often Windows
> tunes around 1MB -- but at other times, it will tune to 3.8MB (way more than
> it should).
> 
> Is anyone aware of any research either pointing out how their tuning
> algorithm works, or of known bugs/problems with the algorithm?

How BDP suggests a receive window of 750k ?

If BDP _is_ 750k, then 3.8 MB receive window is not insane, it depends
on the amount of drops and how fast you want to recover from drops.

1MB would be to small as a matter of fact.