Bird
Raised Fist0

If a system uses preemptive SJF scheduling but the burst times of processes are not known in advance and must be estimated, which challenge is most likely to affect scheduling accuracy?

hard🎤 Interviewer Follow-up Q15 of Q15
Operating Systems - Shortest Job First (SJF) - Preemptive vs Non-Preemptive
If a system uses preemptive SJF scheduling but the burst times of processes are not known in advance and must be estimated, which challenge is most likely to affect scheduling accuracy?
AIncorrect burst time estimates can cause frequent unnecessary preemptions
BThe scheduler will always pick the wrong process due to estimation errors
CNon-preemptive scheduling must be used instead to avoid errors
DStarvation is eliminated because estimates prevent preemption
Step-by-Step Solution

  1. Step 1: Understand burst time estimation impact

    Estimations can be inaccurate, causing the scheduler to preempt based on wrong assumptions.

  2. Step 2: Analyze consequences

    Frequent unnecessary preemptions increase overhead and reduce efficiency.

  3. Step 3: Why other options are incorrect

    B: Scheduler won't always pick wrong process; estimates can be close.
    C: Non-preemptive scheduling is a design choice, not forced by estimation.
    D: Starvation is not eliminated by estimates; it depends on scheduling policy.

  4. Final Answer:

    Option A -> Option A

  5. Quick Check:

    Estimation errors cause scheduling inefficiency via unnecessary preemptions.
Quick Trick: Bad burst time estimates cause too many preemptions in preemptive SJF [OK]
Common Mistakes:
MISTAKES
  • Assuming estimates always cause wrong scheduling
  • Believing estimation removes starvation
Trap Explanation:
PITFALL
  • Option A is too absolute; option D incorrectly links estimation to starvation elimination.
Interviewer Note:
CONTEXT
  • Tests deep understanding of practical challenges in implementing preemptive SJF with unknown burst times.
Master "Shortest Job First (SJF) - Preemptive vs Non-Preemptive" in Operating Systems

2 interactive learning modes - each teaches the same concept differently

SolutionTrace

Want More Practice?

15+ quiz questions · All difficulty levels · Free

Free Signup - Practice All Questions
More Operating Systems Quizzes
Banker's Algorithm - Safe State & Resource Allocation - Banker's Algorithm - Safe State & Resource Allocation - Quiz 5medium Dining Philosophers - Problem, Deadlock & Solution - Dining Philosophers - Problem, Deadlock & Solution - Quiz 5medium Dining Philosophers - Problem, Deadlock & Solution - Dining Philosophers - Problem, Deadlock & Solution - Quiz 3easy File Allocation Methods - Contiguous, Linked, Indexed - File Allocation Methods - Contiguous, Linked, Indexed - Quiz 8hard Inode Structure - File Metadata & Block Pointers - Inode Structure - File Metadata & Block Pointers - Quiz 10hard Paging vs Segmentation - Address Translation - Paging vs Segmentation - Address Translation - Quiz 13medium Process vs Thread - Key Differences - Process vs Thread - Key Differences - Quiz 3easy Semaphore vs Mutex - When to Use Which - Semaphore vs Mutex - When to Use Which - Quiz 3easy Semaphore vs Mutex - When to Use Which - Semaphore vs Mutex - When to Use Which - Quiz 15hard Thrashing - Working Set Model & Prevention - Thrashing - Working Set Model & Prevention - Quiz 5medium