Operating system (part - 2) Multi-Tasking vs Multi-Threading

In the Operating system (Part - 1) we learned about

• "what is an operating system"

• What will happen if there is no OS?

• some key functions of OS

• Some of the goals of OS

• types of os

• some real-world examples where these os are used

In part - 2 we will learn what is Multi-Tasking and Multi-Threading and will compare the two.

So let's get started

Before learning about these concepts we should know what is a "Program" and "Process".

What is a Program?

A program is a set of instructions that are written in a programming language and compiled into an executable file that can be run on a computer. Once the program is compiled, it is stored on the computer's disk as an executable file, which can be executed by the computer's operating system. When a user wants to run the program, they can simply double-click on the executable file and the operating system will load the program into memory and execute its instructions. The program will then perform its specified job or operation on the computer.

What is Process?

When a program is executed, it becomes a process in the computer's operating system. A process is loaded into the computer's primary memory, also known as RAM (Random Access Memory), where its instructions are read and executed by the processor. As the program runs, it may read and write data from/to the memory, and the processor may allocate and deallocate memory dynamically as needed. The operating system manages the execution of processes, allocating system resources such as memory, CPU time, and input/output operations to each process as needed. Once a process completes its execution or is terminated, the memory it was occupying is released and made available for other processes to use.

What is a Thread?

• A thread is a separate, independent sequence of instructions within a process that can be executed concurrently with other threads within the same process. Threads are often referred to as "lightweight" processes because they share the same memory space as the process they belong to and require less overhead to create and manage than a separate process.

• Threads are used to achieve parallelism within a process by dividing its tasks into independent paths of execution. By doing so, multiple threads can execute different parts of the process simultaneously, making it possible to take advantage of multi-core processors and improve overall performance.

• Examples of applications that use threads include web browsers (where multiple tabs can be loaded and rendered concurrently), text editors (where spellchecking, formatting, and saving can be done concurrently by multiple threads), and multimedia software (where video and audio processing can be done concurrently).

Now let's see the difference between Multitasking and Multithreading

Thread scheduling:-

Thread scheduling refers to the process by which the operating system decides which thread should execute next on the CPU. Thread scheduling is an important part of managing threads in a program because it determines how efficiently and fairly resources are allocated to different threads.

Comparison between Thread Context Switching and Process Context Switching: -

In summary, Thread Context Switching involves saving and restoring the state of the executing thread within the same process, which is a fast process that doesn't involve switching of memory address space. Process Context Switching, on the other hand, involves saving and restoring the state of the entire process, including its memory address space, which is a slow process that happens when switching between independent processes. Additionally, Thread Context Switching preserves the CPU cache state, while Process Context Switching flushes the CPU cache state.

tune in for the next part.......