This looks good.  Running 2 ports at once, ISDN @ 64 on an ESP board and
v.34 at 28.8 on a 16550 port -- outgoing data on the ISDN line, incoming
data on the modem.

2-3K outgoing on isdn, 4-6K incoming on v.34 and nary a silo overflow.
In the -current kernel from a week or so back, I was getting many with
this (admittedly peculiar) setup.

I will push on this a bit harder over the next few days.

-j