When comparing FCFS scheduling to Shortest Job First (SJF), which statement about average waiting time complexity is correct?

medium🪤 Complexity Trap Q6 of Q15

Operating Systems - FCFS Scheduling - Convoy Effect & Waiting Time

ASJF can achieve lower average waiting time but requires sorting, increasing complexity to O(n log n).

BFCFS always has better average waiting time complexity than SJF.

CBoth FCFS and SJF have identical average waiting time and complexity.

DFCFS has higher complexity due to managing process priorities.

Step-by-Step Solution

Solution:

Step 1: Compare average waiting times
SJF minimizes average waiting time by scheduling shortest jobs first.
Step 2: Analyze complexity
SJF requires sorting processes by burst time, O(n log n).
FCFS schedules in arrival order, O(n).
Final Answer:
Option A -> Option A
Quick Check:
SJF trades higher complexity for better average waiting time [OK]

Quick Trick: SJF sorts processes, increasing complexity but reducing wait time [OK]

Common Mistakes:

MISTAKES

Trap Explanation:

PITFALL

Candidates confuse waiting time quality with complexity, ignoring sorting overhead in SJF.

Interviewer Note:

CONTEXT

Evaluates trade-offs between scheduling algorithms in complexity and waiting time.

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