OS MODULE 2 BCS303 Operating System | 22 Scheme VTU 3rd SEM CSE

Summary

In this video, the presenter covers key concepts of operating systems related to process scheduling. Topics include process definition, memory division, process states, control blocks, and scheduling types like FCFS, SJF, and priority scheduling. The video explains multi-threaded programming, interprocess communication, and synchronization methods. It also touches on important algorithms used for process scheduling, such as round-robin and multi-level queue scheduling. The content is designed to help students easily grasp these concepts for exam preparation, promising an understanding that can lead to scoring over 80% in exams.

Takeaways

• 😀 A process is a program under execution, with memory divided into four sections: stack, heap, data, and text.
• 😀 A process can be in one of five states: new, ready, running, waiting, or terminated.
• 😀 The Process Control Block (PCB) stores crucial information such as process state, program counter, CPU registers, and scheduling information.
• 😀 Process scheduling involves determining which process will run first, using schedulers categorized as long-term, short-term, and medium-term.
• 😀 Processes can be classified as CPU-bound or I/O-bound, with the latter spending more time on I/O operations.
• 😀 Context switching refers to switching between processes, and new processes can be created via the 'fork' function.
• 😀 Inter-process communication (IPC) allows processes to communicate via shared memory or message passing systems, with synchronization methods like blocking and non-blocking.
• 😀 Multi-threaded programming involves using threads, the basic unit of CPU scheduling. Threads can be user-level or kernel-level.
• 😀 Process scheduling algorithms include First Come First Serve (FCFS), Shortest Job First (SJF), Priority Scheduling, Round Robin, and multi-level queue scheduling.
• 😀 Multi-level feedback queue scheduling dynamically adjusts priorities of processes based on CPU usage and waiting time, ensuring a balanced execution order.

Q & A

What is the definition of a process in operating systems?

A process is a program that is under execution. It represents the dynamic state of a program and includes both the program's code and the associated data required for execution.

What are the four sections into which a process's memory is divided?

The four sections of a process's memory are: Stack (for local variables), Heap (for dynamic memory allocation), Data Section (for global variables), and Text Section (for the compiled code).

What are the different states of a process?

A process can be in the following states: New, Ready, Running, Waiting, and Terminated. These states represent the lifecycle of a process from creation to completion.

What is the purpose of a Process Control Block (PCB)?

A Process Control Block (PCB) stores essential information about the process, such as its state, program counter, CPU registers, memory management data, and I/O information.

How does process scheduling work in an operating system?

Process scheduling involves determining which process to execute next. It is managed by schedulers, which use algorithms to allocate CPU time to processes. There are three types of schedulers: long-term, short-term, and medium-term.

What are the two main types of processes in terms of CPU usage?

Processes are categorized into I/O-bound processes, which spend more time on input/output operations, and CPU-bound processes, which spend more time on execution and computation tasks.

What is context switching in operating systems?

Context switching refers to the process of saving the state of a currently running process and loading the state of another process so that it can be executed, allowing multitasking on the CPU.

What is Interprocess Communication (IPC) and how does it work?

Interprocess Communication (IPC) enables processes to communicate with each other. It can be done through shared memory systems, where processes access common memory, or message passing systems, where messages are sent between processes.

What are the key differences between user-level threads and kernel-level threads?

User-level threads are managed by user applications and do not require kernel support, whereas kernel-level threads are managed by the operating system and benefit from better resource management and multitasking.

What is the difference between preemptive and non-preemptive scheduling?

In preemptive scheduling, a process can be interrupted and replaced by another before it finishes executing, while in non-preemptive scheduling, the currently running process cannot be interrupted until it completes its execution.