Operating System Fundamentals Flashcards

What distinguishes a microkernel architecture from a monolithic kernel?

Answer: Microkernels keep only essential functions in kernel space and run services in user space

Microkernels minimize the kernel by running services like file systems and drivers in user space, improving modularity.

What happens during a context switch?

Answer: The CPU saves the current process state and loads the state of the next scheduled process

A context switch saves the PCB of the running process and restores the PCB of the next process to run.

Which page replacement algorithm has the lowest page fault rate theoretically?

Answer: Optimal (OPT)

The Optimal algorithm replaces the page that will not be used for the longest future time, minimizing page faults.

In Unix, what does the 'fork()' system call return to the parent process?

Answer: The PID of the child process

fork() returns the child's PID to the parent, and 0 to the child — allowing each to identify its role.

What is the purpose of a 'mutex' (mutual exclusion lock)?

Answer: To ensure only one thread accesses a critical section at a time

A mutex ensures that only one thread can hold the lock and execute within the critical section at any given time.

Which of the following is an example of non-preemptive CPU scheduling?

Answer: First-Come First-Served (FCFS)

FCFS is non-preemptive because once a process starts executing, it runs to completion or until it voluntarily yields.

What is 'internal fragmentation' in memory management?

Answer: Unused memory within an allocated block due to fixed-size partitions

Internal fragmentation is wasted space inside an allocated memory partition when the process doesn't need all of it.