Time-slicing for equal priority tasks in FreeRTOS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is time-slicing in FreeRTOS?

Time-slicing is a method where tasks of equal priority share CPU time by switching between them at regular intervals, ensuring each gets a fair chance to run.

beginner

How does FreeRTOS decide which equal priority task to run during time-slicing?

FreeRTOS uses a round-robin approach, switching between tasks of the same priority every tick interrupt to give each task CPU time.

intermediate

Which FreeRTOS configuration setting enables time-slicing for equal priority tasks?

The configuration setting `configUSE_TIME_SLICING` must be set to 1 to enable time-slicing in FreeRTOS.

intermediate

What happens if time-slicing is disabled in FreeRTOS for equal priority tasks?

If time-slicing is disabled, the first ready task of equal priority runs until it blocks or yields, potentially starving other tasks of the same priority.

beginner

Explain why time-slicing is important for tasks with equal priority in FreeRTOS.

Time-slicing ensures fairness by allowing all equal priority tasks to run in turn, preventing any single task from monopolizing the CPU.

What scheduling method does FreeRTOS use for tasks with equal priority when time-slicing is enabled?

A Round-robin

B First come, first served

C Priority inversion

D Random selection

FreeRTOS uses round-robin scheduling to switch between equal priority tasks during time-slicing.

Which configuration option must be enabled to allow time-slicing in FreeRTOS?

A configMAX_PRIORITIES

B configUSE_PREEMPTION

C configUSE_TIME_SLICING

D configUSE_IDLE_HOOK

The configUSE_TIME_SLICING option enables time-slicing for equal priority tasks.

If time-slicing is disabled, what happens to equal priority tasks in FreeRTOS?

A All tasks run simultaneously

B Tasks run in parallel

C Tasks are scheduled randomly

D Only the first ready task runs until it blocks or yields

Without time-slicing, the first ready task runs until it blocks or yields, which can cause other equal priority tasks to wait.

How often does FreeRTOS switch between equal priority tasks during time-slicing?

A Only when a task blocks

B At every tick interrupt

C Every second

D When manually triggered

FreeRTOS switches tasks at every tick interrupt to share CPU time fairly among equal priority tasks.

Why is time-slicing important in a real-time operating system like FreeRTOS?

A To ensure fairness among equal priority tasks

B To increase CPU speed

C To reduce memory usage

D To disable interrupts

Time-slicing ensures that all tasks with the same priority get CPU time fairly, preventing any single task from dominating.

Describe how FreeRTOS manages CPU time among tasks with equal priority when time-slicing is enabled.

Think about how the system switches tasks regularly to be fair.

Explain the consequences of disabling time-slicing for equal priority tasks in FreeRTOS.

Consider what happens if one task never stops running.