The most important goal of a real-time kernel scheduler is to ensure SWSRPS. The scheduler in the CONFIG_PREEMPT_RT kernel uses push and pull algorithms to balance and correctly distribute real-time tasks across the system. Both the push and pull operations try to ensure that a real-time task gets an opportunity to run as soon as possible. Also, in order to reduce the performance and scalability impact that might result from increased contention of global variables, the scheduler uses the concept of root domains and CPU priority management. The scope of the globalrnvariables is reduced to a subset of CPUs as opposed to the entire system, resulting in significant reduction of cache penalties and performance improvement.
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