Preemptive scheduling behavior in FreeRTOS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is preemptive scheduling in FreeRTOS?

Preemptive scheduling means the system can stop a running task to start a higher priority task immediately.

beginner

How does FreeRTOS decide which task to run next in preemptive scheduling?

FreeRTOS always runs the highest priority task that is ready to run. If a higher priority task becomes ready, it preempts the current task.

intermediate

What happens if two tasks have the same priority in FreeRTOS preemptive scheduling?

FreeRTOS uses time slicing to share CPU time between tasks of the same priority, switching between them regularly.

intermediate

Why is preemptive scheduling useful in real-time systems?

It ensures important tasks run immediately when needed, improving system responsiveness and meeting timing requirements.

intermediate

What role does the tick interrupt play in FreeRTOS preemptive scheduling?

The tick interrupt triggers the scheduler regularly to check if a higher priority task is ready and switch tasks if needed.

In FreeRTOS preemptive scheduling, what happens when a higher priority task becomes ready?

A The current task continues until it finishes

B The scheduler immediately switches to the higher priority task

C The higher priority task waits until the current task yields

D The system crashes

Preemptive scheduling means the scheduler switches immediately to the higher priority task when it becomes ready.

What mechanism allows FreeRTOS to switch tasks regularly among same priority tasks?

A Time slicing

B Task suspension

C Interrupt nesting

D Priority inversion

Time slicing lets FreeRTOS share CPU time fairly among tasks with the same priority.

Which component triggers the FreeRTOS scheduler to run periodically?

A Idle task

B Watchdog timer

C Tick interrupt

D Memory manager

The tick interrupt fires regularly to let the scheduler check if a task switch is needed.

Why is preemptive scheduling important in real-time applications?

A It reduces power consumption

B It simplifies programming

C It avoids task switching

D It ensures critical tasks run on time

Preemptive scheduling helps meet timing needs by running important tasks immediately.

If a low priority task is running and a higher priority task becomes ready, what does FreeRTOS do?

A Switches immediately to the higher priority task

B Waits for the low priority task to finish

C Runs both tasks simultaneously

D Disables the higher priority task

FreeRTOS preemptively switches to the higher priority task as soon as it is ready.

Explain how FreeRTOS preemptive scheduling manages tasks with different priorities.

Think about what happens when a more important task needs the CPU.

Describe the role of the tick interrupt in FreeRTOS preemptive scheduling.

Consider how the system knows when to switch tasks.