I am using FreeBSD on an ARM/XScale processor using 2.6 of the Linux kernel.

I have a C program that has a main thread and a callback function that is driven from a timer interupt. I looked into pthread_mutex but I don't like it for 2 reasons: it does not support recursion (not in Linux), but more importantly, will wait for the mutex to become available (not good in my case).

What I would like to do is up the priority of a small section of code to the highest level (time critical?) and return to the normal state shortly thereafter. Really what I want to implement is a critical section where no other processes or tasks can run. Does anyone know what calls I need to make? I can handle the recursion with some code once I get a handle on the task scheduling. Any code snips would be great.

Thanks!

FreeBSD with a Linux kernel ??

I think you can do the scheduling trick with Solaris, an O/S that supports the RT (real-time) scheduling class.

not FreeBSD - BusyBox. My bad. Too many hours....

Actually, I am looking at the sched_ functions now which seems to be a step in that direction. I haven't figured out what the performance hit to switch back-and-forth would be.

I am also reading up on the real-time Linux flavors....

HI

wel their are different scheduling policies in linux e.g
NORMAL
FIFO
..
which have different priorities
and you can switch between these policies useing system call
sched_setscheduler(..)
refer to man pages for more help on this system call