This is purely a Linux issue and it doesn't belong in a Java
newsgroup.

Disabling multitasking is not the way to solve your problem, and even
if it were possible it would likely cause more trouble than it's
worth. Even a "completely unloaded" system has at least a dozen or so
necessary processes running, and once you log in using a desktop
manager like Gnome or KDE that number increases to around 35 even
before you run any "normal" applications.

To solve the problem (not just the symptom) you should probably be
using some kind of flow control between your application and the
device connected to the serial port.

Finally, use a realtime version of Linux if your application needs
that kind of behaviour. Start by looking here: http://www.rtai.org/

/gordon

Sorry,  I stopped reading after this, since clearly you don't want my
advice.

(Hint: excluding one gender from your salutation is a bit rude.)

Raam,

This sounds more like a linux question than a java question.  If
you're using Enterprise RedHat, you probably have a support contract
(sorry if I'm wrong about this).  If not, there are many linux mailing
lists and news groups.

I don't know the answer to your question, but here are a few thoughts:

I don't know if you are developing this program for your own company
or for use by customers, but you might look into a Linux-based RTOS
(real time operating system), where processes are more rigorously
controlled.  I don't know if you can run the Java app you have on a
RTOS, though.

I find it really odd that other applications being open would affect
your program.  I wonder if it's actually a bug in the serial driver
you're using.