Colleagues

I have never programmed in Linux, but now there is  no chance to avoid 
it. I should  try, but do not know how to start.
I plan to use Cortex-A9 with two cores, where on one of the core should 
run very small but fast task (shorter than 10us, program like for the 
microcontroller), and the other should be under Linux. Interrupt could 
be a solution for me, but it happens every 10 usec and need to be 
calculated in a few usec.
Can somebody give me an idea how to get started with linux. Whether it 
is possible to do that the task will execute on a separate core 
independently from the rest of Linux?

Thanks!

Dmitry