Re: 2.6.10 TCP troubles -- suggested patch

[Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>]

Hello!

> Actually, it may think slow start is being done - there was enough 
> small packet back and forth on the connection before the "heavy 
> transfer" to get cwnd opened

If receiver sent an ACK it still does not mean that sender used it
to increase its cwnd. Particularly, small packet exchange definitely
does not inflate cwnd.


> output.  All the stacks with ACK avoidance with which I am familiar do 
> not make the assumption that the sender is not doing slow-start.  They 
> make sure to send enough ACKs at the beginning (or after packet loss) 
> to allow the sender's cwnd to grow.

Well, we do similar thing with delayed ACKs. And it took a few of runs
of testing to understand that we cannot detect even packet loss reliably
enough. :-)

Actually, those receivers could use the first delayed ACK event as
a sign of failure of their heuristics and block stretching acks for
this connection.

Alexey