attach preempt_notifier to user process in linux

[maheshma]

I am needing to identify whether a user process was ever preempted somehow, I understand we have hooks in preempt.h and sched.c which allow us to define preempt_notifiers which can in turn call sched_in and sched_out functions whenever a process is rescheduled or preempted.

But I still can't find out how can I attach a notifier to a particular process or pid in user space and then somehow log if this particular process was ever pre-empted. I'm assuming I have to write a module to do so, but how would I go about attaching a pid to a particular notifier?

[Rubberman]

And why do you need to do this? Is this a critical process that cannot/should not be preempted?

[maheshma]

I am doing this for a Project i am working on right now , I did figure out on how to call this function .
see - stackoverflow.com/questions/11939104/attach-preempt-notifier-to-user-process-in-linux/12115450#12115450]attach preempt_notifier to user process in linux

But I am currently stuck with an issue with system freeze when the function is actually calling the notifier , I believe i am somehow corrupting the scheduler , any ideas on how to debug this ?

[Rubberman]

Have you installed the debug kernel and associated sources? Also, there is the kernel debugger kdb which you need to install. Here is a link that may help: KDB - eLinux.org