sio interrupt level overflows

[Wojciech Puchar]

what's the source of this so very often messages?

Jul 19 22:44:17 chylonia kernel: sio2: 9 more interrupt-level buffer
overflows (total 279433)
                 ^^^^^^

after about 1 day uptime and 200MB traffic through sio at 230400bps (set
to 28800 for FreeBSD while it's ISA card with 8x multiply and 16550A
chips).


how to get rid of them? under high load it makes quite high
percentage of packet loss.