Comparing the real time scheduling policies of the Linux kernel and an RTOS

Normal Linux Kernel is a preemptive kernel but not real time, of course. In most multithreading environments (also called multitasking), a preemptive kernel allows the thread that has higher priority to receive longer time on the processor. And, conversely a lower priority thread will have less time with the processor.

However, in the normal kernel, no particular thread can monopolize the services of the resident processor all the time, no matter what its priority. So, programs will never hang up even if an arbitrary thread of the program goes into a “forever loop.”