Petr,
> I have a problem with serial line. We are using PC to read 4
> x RS485 on
> 115kbps. We was using linux and we had serial line overrun
> when we start
> X-windows and when we copy large file from one harddisk on
> primery IDE
> to second harddisk on secondery IDE.
This is not at all surprising.
> We changed our program
> to real-time
> linux and change driver for serial coms to hard irq and use
> rtl-fifo to
> save the data on disk.
> We still have overrun when the large file is copy from one disk to
> onother disk from primary IDE to secondary IDE. We didnot have this
> problem with older PC motherbords. It is very interesting
> because we are
> using communication card with 16 byte FIFO, so the time when the
> interrupt is disabled (by what?) is 0.00125s!!
How big are your RT FIFOs? If they are fairly small, the problem
may not be with the interrupt getting disabled but rather with FIFO overruns
when the Linux process that copies the FIFO to a file gets preempted. If
your RT FIFOs are smaller than 16384 or so, I would try making them much
larger first. Even the most memory starved system can afford 16KB for a
FIFO.
> Do you know where is the problem and what to do to remove it?
If a larger FIFO does not help, then the next question is what
version of X are you using and how much screen activity are you seeing? If
the answer is 4.x and lots, then you might try going back to X 3.x.
Hope this helps.
Steve Cohen
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