Re: Current 2.6.x TSO state

["David S. Miller" <davem@davemloft.net>]

On Fri, 1 Oct 2004 21:51:47 +0200
Andi Kleen <ak@suse.de> wrote:

> > >      max win adv:            5840 bytes     max win adv:           63712 bytes
> > >      min win adv:            5840 bytes     min win adv:            5792 bytes
> > 
> > That stinks that the receiver is only using a 64K window,
> > that's way too small for gigabit.
> 
> Just using the default, no tuning.
> 
> I have some patches in the pipeline to do automatic window tuning
> based on link speed based on dev->features. But they were actually more 
> intended for 10Gbit/s (where all the defaults are completely inadequate)  
> And it needs a bit more work. 

As mentioned, the TCP receive buffer auto-tuning takes care
of all of this in 2.6.6 and later.  It's just 2.6.5 doesn't
have John Heffner's auto-tuning code which is why your test
case is so stuck in the mud.

Also, the stretch ACK's are quite normal.  If the receiver can't
advertize a larger window, we won't spit out an ACK until
the ack timeout.