Computer Science: Operating Systems

What is the primary difference between a process and a thread regarding memory space?

A process has its own independent address space, whereas threads within the same process share the same address space and resources.

Define 'Turnaround Time' in the context of CPU scheduling.

Turnaround Time is the total amount of time taken from the moment a process is submitted to the moment it completes execution.

What is the main difference between shared memory and message passing in Inter-Process Communication (IPC)?

Shared memory allows processes to access a common buffer directly, while message passing requires the kernel to mediate communication between processes.

What is 'paging' in memory management?

Paging is a memory management scheme that eliminates the need for contiguous allocation of physical memory by dividing physical memory into fixed-size blocks called frames.

What does an 'inode' typically store in a Unix-like file system?

An inode stores metadata about a file, such as its size, permissions, owner, and pointers to data blocks, but it does not store the filename.

What is the purpose of a system call?

A system call provides a programmatic interface for user-level applications to request services and resources directly from the operating system kernel.

Explain why context switching between threads is generally faster than context switching between processes.

Thread switching is faster because threads share the same address space, meaning the OS does not need to switch page tables or flush the Translation Lookaside Buffer (TLB).

How does the Round Robin algorithm handle time slices, and what is the trade-off of a very small quantum?

Round Robin assigns a fixed time quantum to each process; a very small quantum increases responsiveness (interactivity) but also increases context-switching overhead, reducing CPU efficiency.

List the four necessary conditions for a deadlock to occur (Coffman conditions).

The four conditions are Mutual Exclusion, Hold and Wait, No Preemption, and Circular Wait.

Explain the concept of 'Belady's Anomaly' and identify which page replacement algorithm it affects.

Belady's Anomaly is the phenomenon where increasing the number of page frames results in an increase in page faults; it specifically affects the FIFO (First-In-First-Out) algorithm.