C191 Operating Systems for Programmers Practice Questions - Set 1 - Part 1

Correct Answer: To store all the information needed to manage a process

A PCB contains process-specific information like process state, process ID, program counter, registers, and memory limits, allowing the operating system to manage processes efficiently.

Correct Answer: To select which process will be executed next by the CPU

The short-term scheduler (CPU scheduler) selects processes from the ready queue to execute on the CPU, ensuring efficient CPU utilization.

Correct Answer: Blocked

A process is in the blocked (or waiting) state when it is waiting for some event, such as I/O completion, to continue its execution.

Correct Answer: The CPU scheduler selects the process to run

A process transitions from ready to running when it is selected by the CPU scheduler for execution on the CPU.

Correct Answer: The process of switching the CPU from one process to another

Context switching occurs when the CPU is switched from executing one process to another. The CPU's state (including registers and program counter) is saved and restored.

Correct Answer: Round Robin

Round Robin scheduling is designed for time-sharing systems, where each process is given a fixed time slice and the CPU switches between processes in a circular queue.

Correct Answer: The process with the highest priority

In priority scheduling, processes are assigned priorities, and the one with the highest priority is selected to run next.

Correct Answer: When multiple processes are stuck waiting on each other’s resources

Deadlock occurs when processes are in a circular waiting state, with each process holding resources that the other processes need to proceed.

Correct Answer: To ensure that only one process accesses a shared resource at a time

Mutual exclusion ensures that when one process is using a shared resource, no other process can access it simultaneously, preventing race conditions.

Correct Answer: Deadlock

The Banker's Algorithm is used to avoid deadlock by ensuring that resource allocation does not lead to unsafe states where deadlock could occur.

Correct Answer: To load processes into the ready queue

The long-term scheduler selects which processes should be brought into the ready queue, regulating the degree of multiprogramming in the system.

Correct Answer: The scheduler can forcibly remove a process from the CPU

Preemptive scheduling allows the operating system to interrupt the currently running process and allocate the CPU to a higher-priority process.

Correct Answer: To minimize response time

Time-sharing systems aim to provide quick responses to user inputs by sharing CPU time between processes, minimizing the waiting time for each process.

Correct Answer: Segmentation

Segmentation can lead to external fragmentation as memory is allocated in variable-sized segments, which can leave gaps between allocated blocks over time.

Correct Answer: To map logical addresses to physical addresses

A page table translates a process's logical (virtual) addresses into physical addresses in memory, facilitating efficient memory management.

Correct Answer: When a process tries to access memory that is not in RAM

A page fault occurs when a process tries to access a page that is not currently in main memory (RAM), prompting the OS to load it from secondary storage.

Correct Answer: Loading pages into memory only when they are needed

Demand paging loads pages into memory only when they are required by the process, which helps reduce memory usage and improves performance.

Correct Answer: Paging

Paging divides memory into fixed-size blocks (pages) and maps them to physical frames, helping to prevent external fragmentation.

Correct Answer: It allows processes to run even if they exceed physical memory limits

Virtual memory enables processes to use more memory than is physically available by paging memory in and out of secondary storage as needed.

Correct Answer: When the CPU spends most of its time swapping pages in and out of memory

Thrashing occurs when there is excessive paging, causing the CPU to spend more time on page faults than executing processes, significantly degrading performance.