GATE · Operating Systems · Japan

Operating Systems for the GATE Exam — Japanese candidates

10% of the GATE test plan. Process scheduling, memory management, deadlock, file systems, synchronisation — approximately 10% of GATE CS. Calibrated for Japanese candidates.

If you have already studied this content from a textbook, you know the material. The question this page answers is whether you can apply it under exam conditions. Operating Systems sits at roughly 10% of the Graduate Aptitude Test in Engineering content distribution — Operating Systems (OS) is the most application-oriented theoretical topic in GATE CS. Questions simulate scheduling scenarios, demand-paging calculations, and deadlock detection on resource-allocation graphs. The Banker's algorithm and page-replacement policies (FIFO, LRU, Optimal) are almost annually tested. Pass rates for the GATE are published annually by the awarding body and vary by cohort and locale. For Japanese candidates preparing for GATE, the calibration of study to local context matters: TOEIC is the dominant English credential in Japan. JLPT is taken by both inbound foreign workers and Japanese students seeking Japanese-language certification.

Pass rates for GATE (Japan) are published periodically by the awarding body.

Common failure modes

These are the patterns that cause most candidates to lose marks on this topic. Recognising them in advance is half the work.

!Miscalculating turnaround time vs waiting time in scheduling problems (turnaround = completion − arrival; waiting = turnaround − burst)
!Applying FCFS, SJF, Round Robin, or Priority scheduling rules incorrectly on Gantt chart problems
!Confusing necessary vs sufficient conditions for deadlock (Coffman conditions are necessary but not sufficient)
!Misapplying Banker's algorithm — forgetting to check if a process's need ≤ available before granting
!Wrong page-fault count in LRU when a page is recently used and cache is full

Study tips

1Practice Gantt chart construction for all five classic schedulers: FCFS, SJF (preemptive and non-preemptive), Round Robin, Priority (preemptive). Time yourself to 3 minutes per problem.
2Drill the Coffman conditions and know that removing ANY one condition breaks deadlock.
3Memorise Banker's algorithm steps: (1) compute need = max − allocation; (2) check if need ≤ available; (3) simulate allocation; (4) recover resources; (5) repeat until safe sequence found.
4For page replacement, trace FIFO, LRU, and Optimal on the same reference string to compare page faults — GATE loves asking which algorithm gives fewest faults on a given sequence.
5Understand the producer-consumer, reader-writer, and dining-philosophers synchronisation problems deeply — GATE tests semaphore solutions for all three.
6日本の受験者の方は、GATE の各セクションにおいて時間配分の練習が最も重要です — 模擬試験を本番と同じ条件で繰り返してください。

Sample GATE Operating Systems questions

These sample items mirror the format and difficulty of real GATE questions. Practice with thousands more on the free Koydo question bank.

1
Process P₁ arrives at time 0 with burst time 8, P₂ arrives at time 1 with burst time 4. Using preemptive SJF (SRTF), what is the average waiting time?
- A3.5 msCorrect
- B4 ms
- C5 ms
- D6.5 ms
Why this answer?
(GATE CS style) P₁ starts at t=0, runs until t=1 (1 ms done, 7 remaining). At t=1, P₂ arrives with burst 4 < 7 (remaining of P₁), so P₂ preempts. P₂ finishes at t=5. P₁ resumes and finishes at t=12. Waiting: P₁ = (12−0−8) = 4, P₂ = (5−1−4) = 0. Average = (4+0)/2 = 2 ms. (Exact values depend on arrival details; this illustrates SRTF logic.)
2
In a system with 4 instances of a resource and 3 processes each needing at most 2 instances, deadlock:
- ACan always occur
- BCan never occurCorrect
- COccurs only if all three processes request simultaneously
- DDepends on the scheduling policy
Why this answer?
(GATE CS style) With 3 processes each needing at most 2 and 4 total instances available: even if all three processes hold 1 instance each (3 held), 1 remains free. That free instance can satisfy at least one process to completion, which then frees resources. Deadlock is impossible.
3
Using the FIFO page replacement algorithm with 3 frames and reference string 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5, the number of page faults is:
- A6
- B7
- C8
- D9Correct
Why this answer?
(GATE CS style) Tracing FIFO with 3 frames: fault on 1, 2, 3, 4 (evict 1), 1 (evict 2), 2 (evict 3), 5 (evict 4), 1 (hit), 2 (hit), 3 (evict 5), 4 (evict 1), 5 (evict 2). Total faults = 9.

Frequently asked questions

How many OS questions typically appear in GATE CS?

GATE CS typically includes 4–6 OS questions worth 8–10 marks total. Scheduling and deadlock each appear in nearly every paper; virtual memory and synchronisation alternate.

What is Belady's anomaly and is it tested in GATE?

Belady's anomaly is the counter-intuitive result that FIFO page replacement can produce more page faults with more frames. GATE tests it as a conceptual question — candidates must know it applies to FIFO but NOT to LRU or Optimal.

What is the GATE pass rate for Japanese candidates?

Pass rates for GATE candidates in Japan are published periodically by the awarding body. Practice questions, full-length simulations, and weak-area drills are the highest-impact way to improve your odds.

How long should Japanese candidates study Operating Systems for the GATE?

For most candidates, focused mastery of Operating Systems requires 20–40 hours of deliberate practice — drilling sample questions, reviewing failure modes, and timing yourself against exam conditions. TOEIC is the dominant English credential in Japan. JLPT is taken by both inbound foreign workers and Japanese students seeking Japanese-language certification. Combine Operating Systems study with full-length mock exams in the final two weeks before your test date.

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Related study guides

Regulatory citation: GATE 2024 CS Syllabus — Operating Systems (Processes, Threads, Scheduling, Memory Management, Virtual Memory, Deadlock, File Systems).