der Mouse  <mouse@Rodents.Montreal.QC.CA> writes:

> >>> de0: abnormal interrupt: transmit underflow (raising TX threshold to 128|512)
> >> [...]
> > This happens minutes after the machine is up with only the most minor
> > bit of traffic on the wire.  After it has step to "store-and-forward"
> > there is no further such changes.  Of course, this might all be
> > related to the odd output errors that seem to occure a lot.
> 
> I admin an alpha with
> 
> de0 at pci0 dev 5 function 0
> de0: interrupting at eb164 irq 2
> de0: DEC DE500-AA 21140A [10-100Mb/s] pass 2.0
> de0: address 00:00:f8:06:29:15
> de0: enabling 100baseTX port
> 
> and every boot, as soon as any significant network traffic occurs, it
> gets such messages, first 96|256, then 128|512, then 160|1024, then
> store-and-forward (at which point, of course, it stops).

FYI, the recent fix to Alpha soft interrupt handling might improve
this.