B CompE Bachelor of Computer Engineering Bachelor of Computer Engineering Operating System 3

Question 1

Which type of kernel runs most OS services in user space, communicating via message passing, improving fault isolation?

Accepted Answer

Microkernel

Answer

A microkernel keeps only essential functions (IPC, basic scheduling, memory management) in kernel space, running drivers and services as user-space processes.

Question 2

In POSIX threads, which function blocks the calling thread until the target thread terminates and retrieves its exit status?

Accepted Answer

pthread_join()

Answer

pthread_join() suspends the caller until the specified thread finishes, then reclaims the thread's resources and retrieves its return value.

Question 3

What is the primary purpose of the Translation Lookaside Buffer (TLB) in a paged memory system?

Accepted Answer

Cache recent virtual-to-physical address translations

Answer

The TLB is a small, fast hardware cache that stores recent page table entries to avoid costly main-memory page table lookups on every memory access.

Question 4

Which disk scheduling algorithm services requests in one direction until the end of the disk, then reverses — minimizing maximum wait time?

Accepted Answer

SCAN (Elevator)

Answer

The SCAN (elevator) algorithm moves the disk arm in one direction servicing all pending requests, then reverses direction, similar to an elevator.

Question 5

In the context of semaphores, what does a binary semaphore initialized to 1 primarily enforce?

Accepted Answer

Mutual exclusion on a critical section

Answer

A binary semaphore initialized to 1 acts as a mutex: wait() acquires it (sets to 0) and signal() releases it (sets to 1), ensuring only one process enters the critical section.

B CompE Bachelor of Computer Engineering Practice Test

B CompE Bachelor of Computer Engineering Practice Test

B CompE Bachelor of Computer Engineering Bachelor of Computer Engineering Operating System 3