Re: How to avoid serial port buffer overruns?

From: Lee Revell
Date: Wed Aug 16 2006 - 19:25:07 EST

On Thu, 2006-08-17 at 00:19 +0100, Russell King wrote:
> On Wed, Aug 16, 2006 at 07:15:06PM -0400, Lee Revell wrote:
> > On Thu, 2006-08-17 at 00:10 +0100, Russell King wrote:
> > > MIDI uses its own driver - sound/drivers/serial-u16550.c. My guess
> > > is there's something in the system starving interrupt servicing.
> > > Serial is very sensitive to that, and increases in other system
> > > latencies tends to have an adverse impact on serial.
> >
> > Have you seen many other reports of serial working reliably in 2.4 but
> > not in 2.6? Right now this is the only clue I have to go on...
> There have been one or two, but the above is basically as far as I've
> got. Unfortunately, I don't have any machines slow enough (or maybe
> with the right hardware) to exhibit the problem.

OK, thanks. FWIW here is the serial board we are using:

The hardware guy says "The mn9845cv, have in default 2 serial ports and
one ISA bus, where we have connected the tl16c554, quad serial port."

Hopefully Ingo's latency tracer can tell me what is holding off


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