Requirements of RT

• Fast context switch
• Minimal functionality (small size)
• Ability to respond to interrupts quickly (Special interrupts handlers)
• Multitasking with signals and alarms
• Special storage to accumulate data fast
• Preemptive scheduling

Requirements of RT (contd.)

• Priority levels
• Minimizing “interrupt disabled” state
• Short-term scheduler (“omni-potent”)
• Time monitor
• Goal: Complete all hard real-time tasks by dead-line. Complete as many soft real-time tasks as possible by their deadline.