Operating System Revision

What is the time quantum in Round Robin Scheduling?

• The time quantum is the maximum time a process can wait in the queue.

• The time quantum is variable and changes with each process.

• The time quantum is the total time a process can run before being terminated.

• The time quantum is a fixed time slice allocated to each process.

Answer explanation

The time quantum in Round Robin Scheduling is a fixed time slice allocated to each process, allowing for fair CPU time distribution among processes. This ensures that no single process monopolizes the CPU.

How does Priority Scheduling determine which process to execute next?

• It selects the process with the highest priority to execute next.

• It selects the process with the lowest priority to execute next.

• It randomly selects any process to execute next.

• It executes the process that has been waiting the longest regardless of priority.

Answer explanation

Priority Scheduling selects the process with the highest priority to execute next, ensuring that more important tasks are addressed before less critical ones.

What is the main difference between a semaphore and a mutex?

• A mutex allows multiple threads to access resources simultaneously.

• A semaphore is faster than a mutex.

• A semaphore is used for thread synchronization only.

• A semaphore allows multiple accesses, while a mutex allows only one access.

Answer explanation

The main difference is that a semaphore allows multiple threads to access a resource simultaneously, while a mutex restricts access to only one thread at a time, ensuring exclusive access.

Name one technique used for deadlock prevention.

• First-Come, First-Served

• Round Robin Scheduling

• Banker's Algorithm

• Shortest Job Next

Answer explanation

The Banker's Algorithm is a deadlock prevention technique that ensures resources are allocated safely, preventing deadlock by simulating resource allocation and checking if it leads to a safe state.

Explain the concept of paging in virtual memory management.

• Paging involves dividing physical memory into variable-sized segments.

• Paging allows for the allocation of contiguous memory blocks only.

• Paging is a technique that eliminates the need for virtual memory altogether.

• Paging divides virtual memory into fixed-size pages and maps them to physical memory frames.

Answer explanation

Paging is a memory management scheme that eliminates the need for contiguous allocation by dividing virtual memory into fixed-size pages, which are then mapped to physical memory frames, allowing efficient use of memory.

Which of the following is the CORRECT scheduling algorithms and their characteristics.

• Round Robin: Fair time allocation.

• Shortest Job First: Prioritizes longest tasks.

• Priority Scheduling: Tasks are executed based on priority levels.

• First-Come, First-Served: Processes are executed based on their required burst time.

Answer explanation

Round Robin ensures fair time allocation by giving each process a fixed time slice. Priority Scheduling executes tasks based on their priority levels, making both descriptions correct. The other options are inaccurately described.

What is a race condition and how can it be avoided?

• A situation where the outcome depends on the sequence of uncontrollable events.

• Race conditions can be resolved by increasing the speed of the program.

• A race condition is a type of race in sports that determines the winner.

• A race condition occurs only in single-threaded applications.

Answer explanation

A race condition occurs when the outcome of a process depends on the sequence of uncontrollable events, often in concurrent programming. To avoid it, synchronization mechanisms like locks or semaphores can be used.

Describe the multilevel feedback queue scheduling algorithm.

• It dynamically adjusts process priorities across multiple queues.

• The multilevel feedback queue scheduling algorithm only uses a single queue for all processes.

• This algorithm assigns fixed priorities to processes without any adjustments.

• The multilevel feedback queue scheduling algorithm is primarily used for memory management.

Answer explanation

The multilevel feedback queue scheduling algorithm is designed to dynamically adjust process priorities across multiple queues, allowing for efficient management of process execution based on their behavior and requirements.

What is the purpose of the Banker's algorithm?

• To facilitate faster transactions between banks.

• To increase bank profits through high interest rates.

• To manage customer accounts and services efficiently.

• To prevent deadlock by ensuring safe resource allocation.

Answer explanation

The Banker's algorithm is designed to prevent deadlock by ensuring that resources are allocated safely. It checks resource requests against available resources to maintain a safe state, avoiding potential deadlock situations.

Explain the variable-partition scheme in memory management.

• The variable-partition scheme allocates memory blocks of varying sizes to processes based on their specific requirements.

• It allocates memory based on a first-come, first-served basis without considering process needs.

• The variable-partition scheme requires all processes to have the same memory size.

• The variable-partition scheme uses fixed-size memory blocks for all processes.

Answer explanation

The variable-partition scheme is designed to allocate memory blocks of varying sizes to processes, allowing for efficient use of memory based on each process's specific requirements, unlike fixed-size schemes.