CP-1 Phase 1 Checkpoint (15 questions) · GATE 2027 Operating Systems

Phase 1

Phase 1 Checkpoint: 15 questions on processes, fork, threads and IPC.

15 questions · 20 marks · 45 minutes. Negative marking on MCQ only: −1/3 mark for a wrong 1-mark MCQ, −2/3 for a wrong 2-mark MCQ. No negative marking for MSQ or NAT; MSQ has no partial credit.

Q1 · MCQ · 1 mark(s) — States

Which transition happens when a higher-priority process arrives under pre-emptive scheduling?

(A) Ready → Terminated
(B) Running → Ready
(C) Running → Waiting
(D) Waiting → Ready

Q2 · MSQ · 2 mark(s) — Transitions

Which transitions are possible in the five-state model?

(A) Waiting → Ready
(B) Ready → Waiting
(C) Running → Terminated
(D) New → Ready

Q3 · MCQ · 1 mark(s) — PCB

When a process is pre-empted, its register values are saved in:

(A) the program's text segment
(B) the disk's boot sector
(C) the heap
(D) its PCB

Q4 · NAT · 1 mark(s) — Fork

for (i = 0; i < 4; i++) fork(); Total number of processes (including the original)?

Numerical answer: ________

Q5 · NAT · 2 mark(s) — Fork

printf("start"); fork(); printf("A"); fork(); printf("B"); Total number of prints?

Numerical answer: ________

Q6 · NAT · 2 mark(s) — Fork

if (fork() == 0) { fork(); printf("1"); } else printf("2"); How many times is 1 printed?

Numerical answer: ________

Q7 · MCQ · 2 mark(s) — Fork values

int x = 5; if (fork() == 0) x = x + 5; else x = x − 5; printf("%d", x); What is printed?

(A) 10 only
(B) 10 and 0, in some order
(C) 5 only
(D) 5 and 5

Q8 · MCQ · 1 mark(s) — Schedulers

Which scheduler runs most often?

(A) Long-term
(B) Medium-term
(C) Short-term
(D) All equally

Q9 · MCQ · 1 mark(s) — Orphan

A parent exits while its child is still running. The child becomes:

(A) an orphan, adopted by init
(B) terminated automatically
(C) a zombie
(D) a thread

Q10 · MSQ · 2 mark(s) — Threads

Which are private to each thread?

(A) Heap
(B) Stack
(C) Program counter
(D) Registers

Q11 · MCQ · 1 mark(s) — User threads

Switching between user-level threads of the same process is fast because:

(A) it switches the CPU to kernel mode
(B) it reloads the whole process's memory
(C) it does not require a system call
(D) it is done by the disk

Q12 · MCQ · 1 mark(s) — Threads vs processes

Compared with processes, threads of one process:

(A) share an address space
(B) cannot run concurrently
(C) have separate address spaces
(D) need pipes to share data

Q13 · MCQ · 1 mark(s) — IPC

Which IPC method works between processes on different computers?

(A) Shared memory
(B) Shared heap
(C) Ordinary pipes
(D) Message passing (sockets)

Q14 · NAT · 1 mark(s) — Pipes

A parent communicates two-way with each of its 4 children using ordinary pipes. Minimum number of pipes?

Numerical answer: ________

Q15 · MCQ · 1 mark(s) — Producer–consumer

The consumer must wait when the shared buffer is:

(A) never
(B) empty
(C) full
(D) half full

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Q1 Answer: (B) · 1 mark(s)

The running process is pre-empted.

(A) is wrong: Impossible.
(C) is wrong: Waiting is for events.
(D) is wrong: Unrelated.

Re-read: Lesson 1.1.1 — Processes: memory layout, process control block and process states

Q2 Answer: (A) (C) (D) · 2 mark(s)

A ready process cannot request I/O.

(B) is wrong: Impossible.

Re-read: Lesson 1.1.1 — Processes: memory layout, process control block and process states

Q3 Answer: (D) · 1 mark(s)

To be restored later.

(A) is wrong: Code is read-only.
(B) is wrong: Unrelated.
(C) is wrong: Not the heap.

Re-read: Lesson 1.1.1 — Processes: memory layout, process control block and process states

Q4 Answer: 16 · 1 mark(s)

2⁴.