PING: Someone on the core team. (Modem Problem)

[Peter Jeremy]

On 2007-Feb-14 00:27:36 -0800, Daniel Rudy <dr2867 at pacbell.net> wrote:
>Changing the slot did help.  I moved it from slot 3 to slot 1.  But, now
>it's dropping characters with a port speed of 57600, and I am also
>getting irq overrun errors from the kernel too now.

This is not good.  Interrupt latency is a bit of a sore point but the
FIFO trigger level is 8 bytes so getting SILO overflows implies a
latency of >1.38msec.  Does sio4 report as [FAST] in the dmesg?

Unfortunately, there's no easy way to change the FIFO trigger level -
you would need to patch the source code (look for FIFO_RX_MEDH in
/usr/sys/dev/sio/sio.c if you want to go down this path).

>  With a port speed of 2400, I do not drop characters.

The FIFO is not enabled at speeds at or below 4800bps.

-- 
Peter Jeremy
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