I have a 4core maching(hyperthreading disabled), SUSE linux 2.6.32, SMP & RT group scheduling enabled, at the boot time all the OS/kernel and other applications are limited to first 2 cores. (using isolcpu)
my need is that I have 2 CPU bound processes (p1 & P2), I want them to 100% occupy the next 2 CPUs separately. And to give them SHED_FIFO policy with 99 priority.

I have successfully bound the processes with sched_setaffinity. Initially P1 & P2 are both working almost 100% CPU (with SCHED_OTHER) each on CPU3 & CPU4 respectively.
But the problem comes when they are given SCHED_FIFO. When P1 is set to SHED_FIFO,
chrt -f -p 99 (pid of P1)
The whole system stalls and become not responding.

But in theory, since there are 4 CPUs, one RT task with max priority should not freez the whole system.

Im trying to understand why this happens, any one have an idea? ( why just one SHED_FIFO task freezes a whole multy core system?)

Thankx in advance.