Checkpointing – Real-time Systems MCQs

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1. What is checkpointing in real-time systems?
(A) Saving the current state of a task so it can be resumed after a failure
(B) Ignoring task deadlines
(C) Disk batch processing only
(D) CPU idle monitoring exclusively

2. The main purpose of checkpointing is to:
(A) Reduce CPU usage only
(B) Enhance fault tolerance by enabling task recovery
(C) Batch file processing exclusively
(D) Disk defragmentation

3. Which type of real-time systems benefits most from checkpointing?
(A) CPU idle exclusively
(B) Batch processing systems only
(C) Hard real-time systems with safety-critical tasks
(D) Disk-only archival systems

4. Which factor determines the frequency of checkpointing?
(A) Memory fragmentation
(B) CPU idle exclusively
(C) Disk batch scheduling only
(D) Task execution time, failure rate, and recovery cost

5. What is a major trade-off in checkpointing?
(A) CPU idle exclusively
(B) Higher checkpoint frequency increases reliability but adds overhead
(C) Disk-only operations
(D) Memory defragmentation

6. In real-time systems, checkpointing is typically used with:
(A) Disk batch-only operations
(B) CPU idle exclusively
(C) Fault-tolerant scheduling and backup tasks
(D) Memory defragmentation

7. What is a full checkpoint?
(A) Partial data logging
(B) CPU idle exclusively
(C) Disk batch-only write
(D) Saving the entire state of a task at a specific point in time

8. What is an incremental checkpoint?
(A) Memory-only snapshot
(B) CPU idle exclusively
(C) Disk-only full write
(D) Saving only the changes since the last checkpoint

9. Checkpointing helps reduce:
(A) Task recovery time after a failure
(B) CPU idle exclusively
(C) Disk batch-only operations
(D) Memory defragmentation

10. Which failure type can checkpointing effectively handle?
(A) Only CPU idle faults
(B) Transient and some permanent faults
(C) Disk fragmentation exclusively
(D) Batch file failures only

11. In distributed real-time systems, checkpointing can be:
(A) Local to each task or coordinated across multiple tasks
(B) CPU idle exclusively
(C) Disk batch-only exclusively
(D) Memory-only snapshot

12. What is the main challenge of checkpointing in real-time systems?
(A) Balancing overhead with recovery effectiveness
(B) CPU idle exclusively
(C) Disk-only operations
(D) Memory defragmentation

13. Checkpointing can be combined with which other fault-tolerance technique?
(A) Memory defragmentation
(B) CPU idle exclusively
(C) Disk batch scheduling only
(D) Primary-backup or redundant task execution

14. What happens after a task failure in a system with checkpointing?
(A) Disk batch-only restart
(B) CPU idle exclusively
(C) The task resumes from the last checkpoint instead of restarting from the beginning
(D) Memory defragmentation

15. Which checkpointing strategy reduces recovery latency?
(A) CPU idle exclusively
(B) Frequent incremental checkpoints
(C) Disk batch-only checkpoints
(D) Memory-only snapshots

16. In multiprocessor real-time systems, coordinated checkpointing ensures:
(A) Memory-only snapshots
(B) CPU idle exclusively
(C) Disk batch-only operations
(D) Consistency across dependent tasks during recovery

17. Checkpointing can help maintain:
(A) Memory defragmentation
(B) CPU idle exclusively
(C) Disk batch-only operations
(D) System reliability and predictability under faults

18. Which overhead is introduced by checkpointing?
(A) Memory defragmentation only
(B) CPU idle exclusively
(C) Disk batch-only operations
(D) Additional processing time and memory usage to save task states

19. A good checkpointing policy in real-time systems must consider:
(A) Disk batch-only scheduling
(B) CPU idle exclusively
(C) Task deadlines, failure rates, and recovery cost
(D) Memory fragmentation only

20. The main advantage of checkpointing in real-time systems is:
(A) Efficient recovery from faults with minimal impact on system deadlines
(B) CPU idle exclusively
(C) Disk batch-only optimization
(D) Memory-only saving