RTOS Scheduling and Priority Inversion | Dataford Interview Questions

Describe how a real-time operating system (RTOS) schedules tasks of varying priorities. What is priority inversion, and how do you mitigate it?

Implement simulate_rtos(tasks, ticks, use_inheritance). Each task is a dictionary with name, priority, release, work_before_lock, lock_for, and work_after_lock. Return the task selected at each tick, using "IDLE" when none is runnable, plus the number of inversion ticks. Higher priorities run first; ties use input order. A task blocked on the mutex cannot run. If enabled, priority inheritance temporarily raises the mutex owner's priority to the highest blocked task priority.

Constraints

1 <= len(tasks) <= 50
1 <= ticks <= 1000
1 <= priority <= 10^6
0 <= release < ticks
0 <= work_before_lock, lock_for, work_after_lock <= 1000
Each task has positive total work
Tasks are listed in deterministic tie-breaking order

Function Signature

def simulate_rtos(tasks, ticks, use_inheritance):

Your question is RTOS Scheduling and Priority Inversion. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Describe how a real-time operating system (RTOS) schedules tasks of varying priorities. What is priority inversion, and how do you mitigate it?

Constraints

1 <= len(tasks) <= 50
1 <= ticks <= 1000
1 <= priority <= 10^6
0 <= release < ticks
0 <= work_before_lock, lock_for, work_after_lock <= 1000
Each task has positive total work
Tasks are listed in deterministic tie-breaking order

Function Signature

def simulate_rtos(tasks, ticks, use_inheritance):

Your question is RTOS Scheduling and Priority Inversion. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.