[Gllug] High-latency RS-232

[TM]

Hi All,

We are facing a problem at work talking to a piece of kit via RS-232
from a Linux box. This problem did not exist in Windows and now a few
guys (from the Windows world) are beginning to question the move to Linux.

This annoys me no end because there is a lot of 'Windows is almighty
good and Linux is a pile of crap' from people who haven't even looked at
the issue properly.

We talk to this piece of kit via RS-232 over TCL. We use xon/xoff. We
have traditionally used Windows and the comms works a treat. Now they
have moved to Linux and the serial port has turned sluggish. It takes
about 1000 characters to stop/pause. Which is way to much.

I suggested fiddling with the niceness of the process. This helped but
wasn't good enough to solve the problem.

They run a 'stock' kernel from Fedora and/or RedHat. Moving to a
different distribution (thinking real-time kernel here) is complicated
because there is a lot of code developed for the current
kernel/distribution.

I think they could just happen to have a serial port with a generic,
poorly optimised driver. I have suggested googling for a serial card
well supported in Linux.

We have also played with the RTS-CTS handshake. This introduces a bunch
of other issues (solvable, no doubt, but requiring time and effort). So,
we would like to sick to Xon/Xoff.

Can anyone suggest ways of tackling the problem please?

Many thanks
TM
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